Engineering Utilities 2 - Midterm to Final Module PDF

BUILDING PLUMBING SYSTEMS CHAPTER 5 Sanitary Drainage Systems CHAPTER 6 The Waste Pipe CHAPTER 7 The Soil Pipe CHAPTER 8 The House Drain CHAPTER 9 The House Sewer CHAPTER 10 The Storm Drain LEARNING OUTCOMES (LOs): a. Gain knowledge and discuss the basi...

BUILDING PLUMBING SYSTEMS CHAPTER 5 Sanitary Drainage Systems CHAPTER 6 The Waste Pipe CHAPTER 7 The Soil Pipe CHAPTER 8 The House Drain CHAPTER 9 The House Sewer CHAPTER 10 The Storm Drain LEARNING OUTCOMES (LOs): a. Gain knowledge and discuss the basic principles of Sanitary / Plumbing design. b. Identify, distinguish and discuss the types of water sources. c. Identify Plumbing Materials, Fittings, and Fixtures and discuss their uses or application. d. Understand and apply the principle of building water system and design. e. Understand the principles of natural laws of nature applied on the installation of waste pipe to achieve effective and efficient plumbing system. f. Identify, distinguish and discuss the types of sanitary piping system. g. Identify, distinguish and discuss the types of house drain. CHAPTER 5 SANITARY DRAINAGE SYSTEMS 5.1 SEWAGE DISPOSAL SYSTEM The collection and safe disposal of human wastes are among the most critical problems of environmental health. Recent statistical reports revealed that most of the water borne diseases such as dysentery, typhoid, diarrhea and other intestinal disorders are prevalent in areas where there is no proper and scientific Sewage Disposal System. It was reported that when human wastes are deposited in a pit, typhoid and dysentery causing organisms do not travel horizontally in the soil. These harmful bacteria neither move by themselves, they were carried in some way. These harmful organisms are carried somewhere through water flows, flies, rodents, cockroaches and other vermin which causes contamination. The daily average volume of human waste or excreta per capita is about 80 grams of feces and 950 grams of urine. When diluted with water at the rate of 30 to 100 gallons per day to form sewage, the solid content becomes a very small portion expressed in milligrams per liter. Of the total sewage solids, about 50% is organic and are subject to rotting. Small as it is in the sewage, and as decomposition continues, it become odorous and dark in colour. And whether fresh or state, it contains harmful organism that causes diseases. It is therefore important not only to know the different types of sewage disposal systems, but also to understand the scientific value of the system. 5.1. Type of Sewage Disposal System 1. The Cesspool is a hole in the ground curbed with stones, bricks, concrete hollow blocks, or other materials laid in such a manner as to allow raw contaminated sewage to leach into the soil. The organic wastes accumulate and finally disposed of by integration process. 2. The Privy is a concrete sealed vault with a wooden shelter constructed for the collection of raw sewage. The disintegration of excrement is accomplished in the same manner as in a cesspool. It is objectionable because of the danger of contaminating the source of water supply. 3. The Septic Tank is a device or receptacle used to expedite the decomposition of the elements contained in a raw sewage waste. Raw sewage consists of water, and settleable solid called organic materials that can be precipitated in a septic tank in a very short time. 4. The Public Sewer Line is a public sewage system, operated and maintained by the government consisting of a sewage treatment plant that conveys the raw sewage from buildings and housed to a disposal system. Engineering Utilities 2 1  Of these four types of sewage disposal, the cesspool and the privy are already obsolete. The prevailing types recommended by the sanitary authorities are the Public Sewer Line and the Septic Tank. 5.2 Public Sewer Line The Public Sewer Line is classified into three types according to the kind of waste it disposes. 1. The Combination Public Sewer is the oldest type of public sewer that conveys both storm water and sanitary wastes. This type of public sewer is already obsolete and no longer allowed by the sanitary authorities. 2. The Sanitary Sewer is a public sewer facility that carries regular sanitary wastes only. It terminates in a modern sewage dispersal plant. Rainwater is not permitted to enter into this type of public sewer. This type of Sewer has two classifications: 1. The Intercepting or Trunk Line Sewer is a sanitary sewer that conveys sanitary waste to a dispersal plant. It is commonly made of concrete pipe that varies in sizes from 0.60 to 3.00 meters in diameter. The pipes are laid underground to a minimum depth of about 3 meters, depending upon the natural contour of the ground. 2. The Tributary Sewer is classified as an intercepting sewer branch. The pipe is made of either vitrified clay or concrete pipe laid in an open trench. It is generally smaller in diameter installed not more than 3 meters below the street grade and terminate into the intercepting sewer. 3. The Storm Drain is another kind of public sewer line that carries storm water. It terminates in a natural drain such as canals, lakes or rivers. Manhole is classified as a device of the main and storm sewer. It serves as man’s access for inspection, cleaning and repair. It is constructed out bricks, stone, adobe or concrete at an interval distance from 75 to 150 meters. The manhole diameter varies from 90 to 120 centimetres provided with iron rungs to serve as ladder for the maintenance crew to reach the bottom. It is provided with well-fitted cover on top, levelled with the road surface. Sewage Ejector refers to the pump that will discharge waste in the sump and transfer it to the house drain installed overhead. Sewage ejector is necessary when the public sewer line was installed at a depth from 2 to 4 meters below the street level. Large buildings with basement may have a deeper excavation making it difficult to drain its waste towards the main sewer by means of gravity. 5.3 THE SEPTIC TANK Septic Tank is a receptacle or vault used to collect organic waste discharge from the house sewer. The main function of a septic tank is to liquefy and precipitate solid waste purifying odorous materials. Sewage that was discharge into the tank is retained. And during its retention period, about 60% to 70% of the suspended solid of the sewage is removed largely by sedimentation to form a semi-liquid substance called sludge. The sludge accumulates at the bottom of the septic tank. Parts of the solids are formed into floating scum. Both the scum and the sludge are processed by anaerobic bacteria and transforming them into liquid and gases. This process is called digestion. The solid matter is reduced in sizes and consequently changed in character. The septic tank therefore combines two processes; sedimentation in the upper portion of the tank and anaerobic decomposition of the accumulated sludge at the bottom. Decomposition of organic matter from human waste is a bacteriological process caused by: 1. Aerobic bacterial called aerobes 2. Anaerobic bacteria called anaerobes 3. Facultative bacteria The life process of aerobic bacteria is in the presence of material oxygen. The anaerobic bacteria on the other hand, functions in the absence of free oxygen. Likewise, facultative bacteria functions even with or without free oxygen. These three types of bacteria have no relation to disease. They thrive naturally in sewage, and will function when conditions are favourable in terms of: Engineering Utilities 2 2  1. Food Supply 2. Temperature 3. Moisture However, even when conditions are favourable, these bacteria will cease to exist in the presence of antiseptics or disinfectants. And to discharge large amount or volume of waste and water containing disinfectants, oil and grease into the septic tank will affect and disturb the bacterial activities therein and may then destroy the purpose for which the septic tank is constructed. The human waste or excreta are decomposed, until the organic matters are transformed into materials that could no longer be utilized by the bacteria in their life process. The process of decomposition is regarded as stabilization. Decomposition caused by anaerobic bacteria which is sometimes referred to as putrefaction, is accompanied by bad odours. On the other hand, aerobic decomposition is not accompanied by unpleasant odour. A sewage that turns dark and smell unpleasantly due to anaerobic decomposition is called Septic. Decomposition caused by aerobic bacteria is accomplished with no definite time and could be within a matter of hours. 5.3.1 Gasses that are produced inside the Septic Tank There are different gases produced inside the septic tank ranging from organic to nonorganic gases. These are: 1. Methane gas (CH₄) is a combination of hydrogen and carbon, a principal component of natural gas. 2. Carbon Dioxide (CO₂) is a combination of carbon and oxygen. It is the simplest oxide of carbon. 3. Carbon Monoxide (CO) is a by-product of methane, classified as poisonous gas. 4. Hydrogen (H₂) evolves as a moist gas from organic waste. 5. Hydrogen Sulfide (H₂S) is a colorless gas with offensive odor. 6. Sulfur Dioxide (HO₂) is also a colorless gas having an irritating odor. These gases are discharged into the atmosphere through the ventilation pipe. 5.3.2 Construction of Septic Tank Septic Tank is constructed from either of the following materials: 1. Reinforced concrete 2. Plastered concrete hollow blocks 3. Prefabricated asbestos 4. Thin metal and plastic The most popular and widely used material for construction of septic tank is plastered concrete hollow blocks or reinforced concrete. Others have not gained acceptance due to cost and durability. 5.3.3 General Conditions in Constructing a Septic Tank 1. The concrete or masonry septic tank is usually constructed in a rectangular form. The reason is to retard the even flow of the waste that is necessary, to avoid disturbing the decomposition processes inside the tank. 2. The minimum inside dimension of a septic tank is 90 centimeters wide by 150 centimeters long. 3. For effective decomposition of the organic materials inside the septic tank, a 120 centimeters depth of the liquid content is necessary. It is not impractical though, to construct a tank of greater depth, provided, that the depth should not be deeper than the natural ground water table. Engineering Utilities 2 3  4. The inlet and outlet inverts of the septic tank shall be long turn sanitary tee. The inverts are installed in the wall of the tank at least 120 centimeters from its bottom equally spaced from both sides. 5. The invert is extended down the liquid of the tank not more than 30 centimeters. This is to assure smooth delivery of the incoming sewage below the scum line. Scum refers to the lighter material that rises to the surface of the water. 6. The bottom of the digestion chamber should be sloped to one low point. The purpose is to gather the settled organic materials into one mass to favor the propagation of the anaerobic bacteria. 7. The septic tank should be provided with a manhole, extended a few centimeters above the surface of the soil to overcome infiltration of surface water. This manhole will serve the purpose of cleaning, inspection and repair of the tank. 8. Septic tanks for large plumbing installations are provided with suspended compartment attached to the ceiling slab of the tank. The baffle plate is extended down the bottom of the tank about 40 centimeters below the scum line. Each compartment of the tank separated by baffle plate is provided with manhole. 9. The Septic Tank should be constructed near the surface of the ground, because the correction of the waste depends upon the extent of oxidation and the existence of anaerobic bacteria. Another kind of bacteria that split and digest the effluent is the aerobic bacteria. A kind of bacteria that survive only in the soil not more than 150 centimeters below the surface. Oxidation of the effluent deeper than 150 centimeters would become extremely difficult. 5.3.4 Size of the Septic Tank So far, there is no mathematic formula ever formulated to arrive in determining a definite size of septic tank. However, sanitary authorities agreed in principle that: 1. For family of 6 persons, the minimum tank capacity should be approximately 1.3 cubic meters with a minimum size of 90 centimeters wide by 150 centimeters long and 120 centimeters depth. 2. A very large tank is not advisable, because the bacterial activities would be retarded. The size of the tank is proportionally based on the number of persons expected to be served. In other words, the volume of the tank has rational proportion with the volume of incoming waste for bacterial activities to be in favorable condition. 3. For residential installation, the practice is to allow 5 to 6 cubic feet of tank volume per person. Thus, a septic tank that will serve a family of 12 persons must have a liquid capacity of 6 x 12 = 72 cubic feet or 538 gallons. (1 cu.ft. = 7.48 gallons). Technical Data in Determining Volume of Septic Tank Minimum width 90 cm Minimum length 150 cm Minimum depth 120 cm For residential buildings to serve larger number of people, allocate 0.14 to 0.17 cu.m. of liquid per person. For small residential house to serve up to 12 persons, the chamber should have a liquid content of not more than 2.0 cubic meters For school, commercial and industrial establishments, the volume of the septic tank should not be less than 0.057 cu.m. nor more than 0.086 cu.m. per person. Where large amount of water waste is coming from the shower bath, laundry and others, it is not advisable to permit entry of these waters into the septic tank. Likewise, all downspout collecting water from the roofs should not be allowed to terminate into the septic tank. Rainwater should be conveyed to the Storm Drain. Engineering Utilities 2 4 5.3.5 Location of Septic Tank Location of the septic tank shall observe the following considerations: 1. The septic tank may be closer to the building it will serve, providing a minimum distance of 2.00 meters from the outside wall. 2. As much as possible, the septic tank should not be located closer to the doors and windows. 3. Septic tank should be at least 15 meters away from any source of water supply. The farther the better. 5.4 Requirements for a Satisfactory Disposal of Human Waste 1. There should be no contamination of ground surface that may enter into the spring or wells. 2. There should be no contamination of surface water, 3. The surface soil should not be contaminated. 4. Excreta should not be accessible to animals, flies, cockroaches, vermin and the like. 5. There should be no odor and unsightly conditions. 6. The methods used should be simple and economical in terms of construction operation. 5.5 Safety Precautions In most cases septic tanks are poorly aerated or ventilated. It lacks free oxygen. Under this condition, an individual entering into a septic tank for making repairs or cleaning purposes, may meet almost instant death. Septic tank may contain harmful and dangerous gases. When repair work or cleaning is to be made, be sure that the septic tank is well ventilated, by removing the manhole cover few days in advance of the work. Another precaution is to supply fresh air inside the tank, while work is being done. Remember that the tank may contain inflammable gases that might be ignited to cause a terrific explosion. If light is needed to work in the dark, an electric emergency light with properly insulated cord should be used. In the absence of electric supply, a flashlight powered by dry cell battery is equally safe. 5.6 Sewage Treatment The effluent removed from the septic tank is still in the stage of objectionable matter. Although these organic matters have been removed, and many of the objectionable gases have been eliminated, still it contains countless number of harmful anaerobic bacteria and objectionable chemical compounds in solution that must be disposed of. There are several methods and processes wherein sewages may be treated. And those that are most commonly used are the activated sludge process, and the trickling or sprinkling filter processes. The detailed scientific analysis of sewage treatment is beyond the scope of this subject in plumbing. But in passing, it is worth mentioning that the treatment of municipal sewage is a complex problem involving scientific aspects outside the sphere of plumbing. The design and construction of a modern sewage disposal plant requires engineering training in all the phases of natural science. Civil works for the design and construction of the structure, mechanical for the construction of equipment plus an extended knowledge of chemistry, physics and bacteriology. Reference: Plumbing Design and Estimate, 2 nd Edition by Max B. Fajardo, Jr. Engineering Utilities 2 5 CHAPTER 6 THE WASTE PIPE In the study of plumbing, it is important to know the different parts of the piping installations and their functions. The effectiveness of plumbing installation depends upon the strict observance of the natural laws of nature such as: gravity and the atmospheric pressure that affect the whole system. Most of the failures encountered in plumbing installation, were due to the non-observance of these natural laws, and the grave abuse of its function. Generally, Waste Pipe is smaller in size than the soil pipe. Smaller because of the kind of waste it receives from the various plumbing fixtures. Among the suspended materials found in the water waste are: grease, lint, matches, hair, garbage, and many other objectionable substances. Plumbing fixtures are too often misused. Household’s refuse of all kinds, are carelessly disposed of, by flushing them through the plumbing system. Indeed, the improper use of plumbing fixtures can only result in waste line stoppage, and deterioration of the pipeline. The drainage installation of a plumbing system comprises three major parts: the Drainage, the Waste, and the Vent, or simply called DWV. The Drainage Pipe refers to an installation that receives and conveys discharges from water closet with or without waste coming from other fixtures. The Waste Pipe is any pipe in a drainage installation that receives the discharges of any fixture except water closet and conveys the same to the soil branch, soil pipe or house drain. Fixture refers to slop sink, lavatory, urinals, bathtub and the like except water closet. The Vent Pipe in a plumbing system function as air passage or conduit to ventilate the drainage and waste pipe installation. As already discussed, solid human waste is discharge by water closet only to either the soil branch, soil pipe, soil stack or house drain. Categorically, any pipe that receives and conveys human waste is affixed by the word “Soil” such as; soil branch, soil stack, etc. Soil Branch refers to a horizontal pipe affixed by the word soil. The word soil connotes a pipe receiving discharges from water closet. On the other hand, if this soil branch does not receive discharges from water closet but from other fixtures only, it will be classified as Waste Pipe. Soil Stack is a vertical pipe installation where the soil branches terminate. The pipe is called stack being installed vertically, and the word soil is affixed because it receives human waste from soil branch. Otherwise, it will again be classified as Waste Stack. When a waste pipe is not directly connected to a soil stack or house drain, it is called Special Waste. 6.1 General Conditions for a Good Waste Pipe Installation 1. The Right Choice of Materials The materials intended for waste pipe installation, could be well selected. The character of the waste to be drained, and the service to which it is intended for, dictates the kind of materials to be used. For instance, any waste pipe line that conveys large amount of acid must specify acid resistant material. Example of which, are fixtures serving chemical laboratories, plating, and engraving establishments and others that uses acid of various kinds. Refused that are coming from domestic and commercial kitchen, contains acid of different kinds, but considerably in small negligible quantity and therefore, does not require the use of an acid resistant pipe. 2. Conservative Use of Fittings The smooth flow of waste inside the pipe is a primary consideration in all types of plumbing installations. Most of the waste pipe line failures were attributed to the unwarranted use of accessories and too many fittings, or because of using the wrong type of fittings in a given location. Conservative use of fittings refers to the right choice of the right kind of fittings for a particular change of directions, turns or offsets. Injudicious use of fittings should not be allowed in plumbing installations. Short cuts that will not allow smooth passage of waste should be avoided. Pipe joints and fittings were specially designed to make smooth changes of directions, turns or offsets. But sometimes, their application may not be in accordance with the purpose for which they were made. Engineering Utilities 2 6  There are many self-proclaimed plumbing experts who install pipes in what they called short cut method. The correct use of joints and fittings were not properly observed. It is maybe because they are so in hurry of the work and their pay as well. But the question is, how sure are we that the installations are clogged free? Pipe installations that fail or break too soon, may have been due to any of the following causes: 1. The use of too many fittings and 2. The use of wrong type of fittings. Recommendations: 1. Do not use short radius fittings on a vertical to horizontal directions or horizontal to horizontal changes. 2. Use long sweep fittings on horizontal changes. 3. For vertical to horizontal direction of changes, the Y and 45° fittings are most appropriate. 4. The T fittings were designed for vertical run with lateral branches only. Its use on horizontal installation will create a tilted or crooked joint connection called “Premature Waste Line Defects.” 6.2 Location of Cleanout The waste pipe installation must be provided with an ample number of cleanouts, strategically located, to be opened in case of pipeline trouble. Cleanout is a receptacle of the plumbing system accessible on floor, walls or ceiling. It is equipped with a plug or flush plate so designed as not to impair the aesthetical view of the room. The location of cleanout must be indicated in the plan. It should be sized equal to the diameter of the waste pipe, where it is to be connected. This is to avoid interference in the cleaning process by means of flexible rod. Cleanout must be readily accessible to the plumber in case of waste line stoppage. 6.3 Right Slope or Grade of Waste Pipe The ideal position of horizontal waste pipe, were those installed at 2% slope. Meaning, the pipe was installed with an inclined ratio of 2 centimeters per meter length. For instance, a 3.00 meters pipe installed as a waste line will have an inclination of 3 x 2 = 6 centimeters. Waste pipe must be of sufficient diameter to afford adequate velocity of flow in order to make them as nearly self-scouring as practical. The latest scientific tests and experiments conducted by the National Bureau of Standards sponsored by the Housing and Home Finance Agency showed that, wet venting and stack venting are safe in certain type of installations. The experiments revealed that the Trap Seal Loss occurs when the grade or slope of the pipe is increased from 2% to 4%. Trap Seal Loss means the loss or escape of standing water inside the P-trap. This is usually caused by siphonage induced by rapid flow of waste inside the pipe. It is referred to as Water Seal Escape. Plumbing installations usually suffer grave abuse of function brought about by human elements. The materials and methods used in food preparation, plus the habits of the housewife, accounts for this. Some people use plumbing fixtures as a means of getting rid of almost any kind of unwanted waste. Waste such as garbage, grease, hair, lint, matches, cigar, paper and the like are found in most clogged waste lines. Take note that, Plumbing installations are not intended to convey materials of this kind of unwanted waste. 6.4 Determining the Size of Waste Pipe The National Plumbing Code on the size of waste pipe provides that: “The waste pipe diameter shall be adequate enough to serve the installation of fixtures in a general way, but the best way is to fit the diameters of commercial pipe into the fixture pattern in the most efficient manner.” Engineering Utilities 2 7  The size of waste pipe intended to receive waste from the fixture must ne of sufficient diameter. This is to accommodate the velocity of flow, making them as nearly scouring as necessary to prevent the silting of the pipe. Scouring means to flush or wash out, to remove dirt or grease by flowing through. There are those who believed that by making the drainage pipe larger than what is necessary, will increase its service efficiency. This belief without scientific basis has triggered disagreement among people in the plumbing industry. Disagreement on this matter however, was resolved when the Uniform Plumbing Code Committee formulated data as guide and references in determining the size of the waste and other drain pipes. Reference: Plumbing Design and Estimate, 2 nd Edition by Max B. Fajardo, Jr. CHAPTER 7 THE SOIL PIPE By definition, pipes that receive and convey discharges of water closet, with or without the discharge coming from the other fixtures to the house drain or house sewer is called Soil Pipe. The word Soil is affixed to pipe installation that carries human waste coming from water closet. Minus the waste coming from water closet, said installation is called Waste Pipe. Soil Pipe installed vertically is called Soil Stack and Soil Branch when installed horizontally. 7.1 The National Plumbing Code on Soil Pipe Provides: 1. That, at least one of the vertical stacks in the plumbing system must extend full size through the roof for the following purposes: a. To ventilate and dispose off the sewer gas above the roof. b. To prevent siphoning of the water trap seal by force of suction. c. To prevent the possibility of back pressure which may force the water seal off the fixture trap. 2. Any structure with a house drain installed, must have at least one soil stack or stack vent, extended full size above the roof not less than 30 cm long and should not be less than 75mm (3”) diameter or the size of the drain whichever is smaller. 3. As general rule, vent stack must be extended and terminate through the roof of the building. When the roof is to be used other than protection from the elements of weather, the vent stack should be extended no less than 2.00 meters above the roof. 7.2 The National Plumbing Code on Soil Pipe Installation Provides that: 1. The Soil Pipe shall be properly concealed or embedded in columns, walls or partitions, installed prior to the construction of the building. 2. The entire installations in building such as the location of fixtures, thickness of the partitions, location of doors and windows, drop ceiling, electrical lay-out and outlets and their relations with each other shall be considered in the pre-planning stages prior to the rough-in work. 3. The soil branch that will be tight and free from liquid or gas leak. Installation workmanship shall be strictly in accordance with the standard practice of the trade involved. 4. Soil Pipe joints shall be tight and free from liquid or gas leak. Installation workmanship shall be strictly in accordance with the standard practice of the trade involved. 5. Soil pipes not embedded in concrete wall, columns or partitions shall be anchored rigidly by means of metal hangers. 6. That changes from vertical to horizontal directions shall be done by using: a. ¼ bend b. Long Sweep ¼ bend c. Two 1/8 bend or d. Combination of Y and 1/8 bend Engineering Utilities 2 8 7.3 Size of the Soil Pipe So far, there is no definite mathematical formula ever formulated to determine the size of the Soil Pipe required for a particular installation, this maybe because of the variable conditions relative to its service. For instance, who can foretell how often one is going to use a plumbing fixture in a given time interval? Likewise, it would be more difficult for a plumber to ascertain how often and what time a plumbing fixture might be used. And to determine the size of the soil pipe on the basis of maximum discharge of all fixtures connected to it in a minute or an hour interval would be nobody’s guess. However, it would be certain that all fixtures connected to the plumbing system, would never be used or flush simultaneously at one point in time. And it would be more impossible for the soil pipe to be carrying a maximum load from all the fixtures connected to it in one single moment. 7.4 THE FIXTURE UNIT In the absence of a definite formulate to use in finding the size of a soil pipe, the Uniform Plumbing Code Committee formulated the Fixture Unit data as the maximum waste discharges per minute interval of a particular fixture. Indeed, the Code provides that the fixture unit be the standard values in determining the size of all plumbing installations. Table 7.1 Fixture Unit Values Table Kind of Fixture Fixture Unit Bathtub 2 Floor drain 1 Kitchen sink 2 Residential sink 1.5 Lavatory or wash basin 1 Laundry tub 2 Shower bath 2 Slop sink 3 Sink, hotel or public 2 Urinal 5 Water closet 6 Combination fixture 3 One bathroom group consisting of water closet, lavatory, bathtub and overhead shower or water closet, lavatory and shower compartment 8 For every 15 square foot roof drain 1 7.4.1 How to Use the Fixture Unit Table in Determining the Size of Soil Pipe: Illustration 7-1: Determine the Soil Pipe diameter to serve 8 water closets, 3 shower bath, 4 urinals, 2 slop sinks and 3 wash basins. Step 1: Solve for the Total Number of Fixture Units using the Fixture Unit Table: 8 water closets x 6 units ……… 48 units 3 shower bath x 2 units ……… 6 units 4 urinals x 5 units ……… 20 units 2 slop sink x 3 units ……… 6 units 3 wash basin x 1 unit …….... 3 units Engineering Utilities 2 9  Total ………. 83 units Step 2: Refer to the Size of Horizontal Fixture Branch and Stack table below: Table 7.2 Size of Horizontal Fixture Branch and Stack Maximum number of fixture units that may be connected to Diameter of Stack with 3 or more Branches Pipe intervals One Horizontal Not over 3 Branch Branches In one Branch Interval Total in Stack mm inch 32 1¼ 1 2 1 2 38 1½ 3 4 2 8 50 2 6 10 6 24 63 2½ 12 20 9 42 75 3 20 30 20 60 100 4 160 240 90 500 125 5 360 540 200 1100 150 6 620 960 350 1900 200 8 1400 2200 600 3600 250 10 2500 3800 1000 5600 300 12 3800 6000 1500 8400 Refer to table above, under Total in Stack, 83 units is between 60 and 500 fixture units which could be served by a 100 mm or 4” pipe diameter. Comments: 1. The total sum of the fixture unit as computed is 83. Even if this number would be increased by 5 times, the 100 mm pipe that could serve up to 500 units will be more than sufficient to serve the 83 units. 2. It seems that the 100 mm pipe is over size to serve an 83 fixture units. However, since 83 units result of the computation falls under the parameter of 100 mm pipe diameter, the provisions of the Code must prevail. No choice, specify 100 mm pipe. Illustration 7-2: Find the size of a soil stack to serve: 2-units water closet; 2-showers; 2-lavatories and 1residential sink. Solution: 1. Find the total number of Fixture Units using Fixture Unit Table: 2 x 6 water closets ………. 12 units 2 x 2 shower bath ………. 4 units 2 x 1 wash basin ………. 2 units 1 x 2 kitchen sink ………. 2 units Total fixture units …… 20 units 2. Refer to the Size of Horizontal Fixture Branch and Stack table, the 20 fixture units is within the limit of 50 mm or 2” pipe diameter. 3. The 38 mm or 1 ½” diameter pipe could not be used because of the limitations set by the Plumbing Code which states that: “No water closet shall discharge into a drain less than 75 mm or 3 inches diameter pipe.” Engineering Utilities 2 10  4. Therefore, a 75 mm pipe diameter will be specified, not the 50 mm, even if it was the result of our computation. 7.5 THE SOIL BRANCH The Soil Branch is a soil pipe installed horizontally with lateral or vertical connections that receives the discharges of water closet with or without additional plumbing fixtures. General Conditions in Installing soil Branch 1. The Soil Branch being concealed in floors, partitions or lowered ceiling should be accessibly provided with sufficient number of cleanouts. 2. Cleanout should be installed wherever changes of soil branch directions are made. 3. Cleanout should be the same in diameter as the soil branch. 4. Cleanout should be located at the farthest end of the branch away from the vertical soil pipe. 5. The use of short radius fittings on soil branch when making a change of direction such as short sanitary Tee, ¼ bend and short L should be avoided. 6. A long radius fitting shall be used for a horizontal to horizontal or vertical to horizontal change of direction. In some instances, the use of short radius fitting is only permitted on a vertical to horizontal change of direction. 7. Soil branch shall be graded properly and carefully aligned. Crooked joint should not be allowed. 8. The efficiency of a horizontal waste installation depends upon the scouring or selfcleaning action for every discharge of waste. Soil branch having a slope more than 2% fall has the tendency of separating the solid waste from the liquid. Water flows faster on high pitch leaving the suspended materials at the bottom of the pipe. On the other hand, pipes with grade less than 2% are also susceptible to stoppage due to retarded flow. 7.5.1 Size of the Soil Branch The flow of waste inside a horizontal pipe, particularly the soil branch, is much different from those inside the vertical stack. The expected efficiency of a liquid flow inside a horizontal pipe depends upon the scouring action for every discharge. If this action could be attained in every pipe installation, stoppage problem could be avoided. Fixture groups differ in design. And to provide a soil branch of the size just to serve each type of fixture would be more difficult and impractical. Although scouring action is no longer a problem when 2% slope is followed, yet satisfactory result may be obtained if pipe of ample diameter is provided with a minimum and maximum fixture limit. How to determine the required size of a soil branch with aid of Fixture Unit Table and Size of Horizontal Fixture Branch and Stack Table, the following example was presented. Illustration7 - 3: What diameter of soil branch is appropriate to serve a battery of 3 water closets? A battery water closet is set of water closet that discharges wastes into a single soil pipe. Solution: 1. Find the total fixture units of 3 water closets. Referring to the Fixture Unit Table. Multiply: 6 units x 3 water closets = 18 units 2. Refer to the Size of Horizontal Fixture Branch and Stack Table, under One Horizontal Branch, a 75 mm diameter pipe could serve up to 20 fixture units. Thus, a 75 mm or 3” pipe could serve well the 18 units as computed. But the Plumbing Code on pipe size limitations states that: “Not more than two water closets shall discharge into any 75 mm diameter horizontal soil branch, house sewer or house drain.” Engineering Utilities 2 11  3. The Code must prevail. Specify a 100 mm diameter for soil branch, not 75 mm as computed. Illustration: What diameter of soil branch will be satisfactory to serve a battery of 25 water closets? Solution: 1. From the Fixture Unit Table, the total fixture units of 25 water closets is: 25 x 6 units = 150 fixture units 2. Refer to Size of Horizontal Fixture Branch and Stack Table. Under One Horizontal Branch column, a 100 mm (4”) diameter soil branch could serve up to 160 fixture units. 3. Therefore, specify a 100 mm diameter soil branch to serve the 25 water closets. Comments: 1. From the two illustrations just presented, it could be seen clearly that a 100 mm diameter pipe is required to serve 3 water closets, while it could satisfactorily serve 25 water closets. Much more, when the Plumbing Code Committee issued a report that a 100 mm pipe could effectively serve 840 fixture units coming from a 140 water closets without the danger of overloading. 2. Would it not be confusing to see disproportional computations like this? It might be confusing, but since the fixture unit was formulated by the Uniform Plumbing Code Committee, the Code must prevail. 7.6 Noise and Condensation Noise is one among the serious problem of plumbing installation. It annoys the occupants. The water rushing down through the soil pipe within the wall creates various unwanted irritating noise. On the other hand, condensation causes the dripping of water inside the ceiling, the number one enemy of wood and other similar or related materials. 7.6.1 Solution to this Problem 1. Soil pipe should not be in contact with plastered walls or ceiling because it will create sounds that are magnified inside the room. Waste and Soil pipes not embedded in concrete must be insulated. Hair felt or mineral wall materials are packed around the waste or soil pipe as insulator to absorb noise. 2. Condensation may be overcome by applying a good quality anti-sweat covering materials to the soil pipe installation. 7.7 Prohibited Fittings and Connections The National Plumbing Code on fittings and connections of soil pipe provides that: A. Prohibited Fitting: 1. Double Hub, Double Tee or Double Y branch should not be permitted on soil or horizontal lines. 2. The drilling and tapping of house drain, soil pipe and waste or vent pipes and the use of saddle hubs or bends are strictly prohibited. B. Dead End Fittings Dead-end connections in any drainage installation should not be permitted. This portion of the plumbing system will only accumulate waste and sludge. Engineering Utilities 2 12 Reference: Plumbing Design and Estimate, 2 nd Edition by Max B. Fajardo, Jr. CHAPTER 8 THE HOUSE DRAIN House Drain is that portion of the plumbing system that receives discharges of all solid and waste stacks within the building, and conveys the same to the House Sewer. House Drain is sometimes referred to as the Collection Line of a Plumbing System. It can be installed underground, or maybe suspended below the floor or inside the ceiling. In large building, house drain is usually suspended from the basement ceiling to avail of the gravity flow of waste to the Main Sewer. Many plumbers still believe that, by making the drain pipe larger than what is necessary, will increase its efficiency. They may not know that the scouring action will increase its efficiency. They may not know that scouring action will not work effectively by increasing the size of the house drain. The solid wastes are carried along the bottom of the pipe, and because the water flow within the larger pipe is shallow, and slow, they become separated from the water, and remains at the bottom of the pipe. The result is clogging of the drain branch, and ultimately, the entire house drain. To assure scouring action, the house drain should be size correctly to have a flow about 50% of the pipe diameter. 8.1 House Drain Classification 1. Combined Drain 2. Sanitary Drain 3. Storm Drain 4. Industrial Drain Combined Drain is a type of house drain that receives discharges of sanitary waste as well as storm water. This is the oldest form of house drain when public sewers are of combination design. This type of house drain however, is already phase out and no longer permitted. Sanitary Drain is a type of a house drain that receives the discharges of sanitary and domestic waste only. The waste is conveyed to a public sewer, or septic tank, by the house sewer. Storm water is not allowed in the sanitary drain. Table 8.1 Size of Sanitary Drain Table Diameter of Pipe Maximum No. of Fixture Units that may be connected to mm inch 2 % Slope 3 % Slope 4 % Slope 32 1¼ 1 1 1 38 1½ 2 2.5 3 50 2 5 7 8 63 2½ 12 13 14 75 3 18 18 21 100 4 84 96 114 125 5 162 216 264 150 6 300 450 600 Engineering Utilities 2 13 200 8 990 1392 2220 250 10 1800 2520 3900 300 12 3089 4320 6912 Storm Drain conveys all storm clear water, or surface water waste except sanitary wastes. Storm drain terminates into lake, river, dry run or natural basin. Industrial Drain is a house drain that receives discharges from industrial equipment that contain some objectionable acid wastes. Industrial drain that contains acid waste terminates into a separate drainage basin. 8.2 Determining the Size of House Drain The Unit System is the most practical method to use in determining the size of a house drain. Plumbing fixtures were individually tested. The amount of liquid waste discharged through their outlet orifices in a given interval was carefully measured. It was found, that a washbasin being the smallest type of plumbing fixture, would discharge waste approximately 7 ½ gallons in one-minute interval. This volume was found out to be closely one cubic foot of water. The Code Committee has finally decided to adopt the washbasin discharge as One Fixture Unit. One fixture unit represents 30 litres of water. Other fixtures discharges were also tested and the corresponding results were established and listed in Fixture Unit Table. Before finding the size of a house drain, its service must be known first, whether the purpose is for sanitary waste or as storm drain. a. If the purpose is for sanitary waste, the Fixture Unit load discharges will be the basis of computation with reference to Fixture Unit Table. b. If the purpose is for storm drain, the roof area that accumulates the major rainfall water will be the basis in determining the size of the pipe (that will be discussed in the succeeding topics). It seems that the approach is quite complex, but simplified with the use of charts and data compiled for years from the installation experiences recorded by the Code Committee. 8.2.1 The Provisions of Plumbing Code on House Drain: 1. No water closet shall discharge into a drain less than 75 mm or 3 inches pipe diameter. 2. No more than two water closets shall discharge into any 75 mm horizontal soil branch, house drain or house sewer. Illustration: Determine the size of a Sanitary House Drain to serve 6 water closets, 5 urinals, 5 shower bath, 6 washbasins, 4 floor drains and 3 combined fixtures. Solution: 1. The house drain is to serve Sanitary Waste. Refer to Fixture Unit Table, the values are: 6 x 6 water closets ………….. 36 units 5 x 5 urinals ………….. 25 units 2 x 5 shower bath ………….. 10 units 1 x 6 wash basins ………….. 6 units 1 x 4 floor drains ………….. 4 units 3 x 3 combined fixture ………….. 9 units Total ………….. 90 Fixture Units 2. Refer to Size of Sanitary Drain Table, under column 2% slope; a 100 mm (4”) pipe could serve 96 fixture units. 3. For a 90 fixture units, specify a 100 mm diameter house drain pipe. 8.2.2 Grade or Slope of the House Drain Numerous tests proved that the sloped of a house drain has contributed mush to the effectiveness of the plumbing system. The house drain being a horizontal pipeline must Engineering Utilities 2 14 produce the necessary velocity and discharge capacity at a certain inclination, to attain scouring action. House drain must function without abnormal or subnormal pressure in the plumbing system. It is recommended under any circumstances that, a 2% slope for the house drain should be maintained. There are instances however, where less than 2% slope was adopted, under the following circumstances. 1. When the depth of the sewer line in relation with the depth of the basement floor is low. 2. Long sewer line would require lower pitch but not be less than 1%. 3. In case the sewer line slope is very slight, installation of the pipe should be guided by levelling instrument for accuracy to prevent sags or trapped piping. The grade or slope of the house drain could be estimated by dividing the total pitch in centimetres (which is the distance between the house sewer and the elevation of the basement) by the length of the longest branch in meter. For instance, if the longest branch of a house drain is 8 meters, and the total drop is 16 centimetres, dividing 16 by 8 metres the value is 2%. A pitch or slope more than 2 %, will increase the velocity and discharge capacity of the pipe, the effect could be: 1. A danger5 that it might decrease the depth of the water that is necessary to create a scouring action. 2. This might cause a minus pressure if the drain is overloaded to a flow capacity. 8.2.3 Change of House Drain Direction Changes of house drain direction are also governed by the following conditions: 1. All changes in directions from horizontal to horizontal, or vertical to horizontal flow, should be done with long radius fittings. Short Tees, ¼ bends and short turn L fittings, should not be permitted. 2. Soil branch should be run Right Angle to the main. 3. Fixture connection must run at Right Angle to the branch. 8.3 House Drain Cleanout On House Drain Cleanout, the National Plumbing Code provides that: 1. The house drain shall be provided with adequate number of cleanouts to prevent breaking of the floor, in case of drain stoppage. 2. The location of the cleanout depends upon the good judgment of the plumber where it is readily accessible, in case of line trouble. 3. Any branch of the house drain terminating at a floor drain or fixture, shall be provided with 100 mm diameter pipe, extended at least 2 inches above the floor inserted in a 45 degrees Y branch in the direction of the drain flow. 4. The cleanout shall be equipped with threaded screw cover provided with a raised head that could be removed easily with a wrench. 5. A cleanout extended above the floor, shall not be utilized as a floor drain. 6. The tarp of a floor drain shall be placed not more than 50 centimetres below the finished floor line, to facilitate cleaning in case of line trouble. 7. A cleanout shall be installed at every 20 metres interval distance, and also at the base of all soil and waste stack. 8.4 House Drain Appliances House Drain appliances the following: 1. House Trap a. House trap assembly b. Back flow valves c. Balances valve d. Unbalanced valve 2. Area Drain 3. Floor Drain 4. Yard Catch Basin Engineering Utilities 2 15  5. Garage Catch Basin 8.5 Garage Catch Basins Includes: a. Drain tile receptor b. Sewage ejector c. Automatic water siphon d. Sump pit e. Grease basins 8.6 House Trap House Trap is defined as a device installed in the house drain immediately inside the foundation wall of the building. It serves as a barrier and prevents the gases coming from the public sewer or septic tank in circulating through the plumbing system. For so many years, the use of house trap has been a controversy that divided sanitary authorities. Some says that, its use is not necessary. Others contend that, it is necessary for the protection of life. In either case, one point that must be accepted as a certainty is that, public sewers are filled with various gases which are common to the science of chemistry as: Oxygen (O), Nitrogen (N), Carbon dioxide (CO₂), Hydrogen (H), Hydrogen sulphide (H₂S), Methane (CH₄), Carbon monoxide (CO), and Sulfur Dioxide (SO₂). Considering the different gases being produced inside the public sewer and septic tank, Sanitary Authorities advocating for the use of house trap contended that: “Whenever an element that is dangerous to health or life is present, even though in small volume, adequate protective measures must be taken. Thus, where noxious gases are present, house trap must be installed on the house drain.” However, Public Authorities favour the elimination of the house trap because its presence adversely lessens the discharge capacity of the sewer. Sanitary authorities established an opinion that sewer gases and the manner how they occur are not detrimental to health, provided, that the plumbing system is properly installed. They concluded further, that an aerated or ventilated sewer would not be gas-producing agency. A liberal attitude relative to the house trap and the advisability of its installation is recommended. 8.7 Back Flow Valve The Back Flow Valve is a device used in a drainage system to prevent the reversal of flow. It is installed in a house drain or branches of the house drain that are subjected to reversal flow of liquid. The back flow valve is installed on the house drain, just near the foundation wall or near the toilet room under floor. It is set in a level position to attain its full effectiveness. Back flow valves are constructed in two patterns and are classified as: 1. The balance valve 2. The Unbalanced valve The Balance Valve is the most preferred, because it has the characteristics of noninterferences in the movement of air inside the drainage system. The Interior mechanism consists of a brass- seat into which fitted a gate counter balanced with an adjustable cast iron weight. The Unbalanced Valve is not illustrated here, but its appearance is similar to the balanced valve. This type of valve is not preferred because of its recorded poor performance in the past. 8.8 Area Drain The area drain assembly consists of running trap installed under the basement floor to protect it from freezing. The trap is equipped with cleanout. The minimum size of an area drain is 100 mm or 4” pipe to drain basement, loading platforms, or driveways. Engineering Utilities 2 16 8.9 Floor Drain A floor drain ids defined as a receptacle used to receive water to be drained from the floor into the plumbing system. Sanitary authorities recognized floor drain as plumbing fixture properly designed and located where to receive liquid floor waste. The Plumbing Code Recommendations on Floor Drain are as follows: 1. An average residence is provided with two floor drains. One located near the heating equipment, and the other in the vicinity of the laundry. In most instances, one floor drain is provided to serve the entire basement. Because of this false economy, the result is an annoying wet floor. 2. Every room where laundry equipment is used shall be provided with adequate floor drain. 3. The drain proper must be located where the overflowing water will not travel a great distance over the floor before it enters the drain. It is recommended that the floor drain be located at one end of the laundry tub. This will assure a dry floor where one stands when using the fixture. 4. Every floor drain shall be supplied with running water from a fixture located nearby. If the fixture is less than 1.50 meters from the drain, it should be tapped but not necessarily vented. 5. Fixture drains which supply water to a floor drain, should be connected to the house side and never to the sewer side of the trap. The most common and frequent trouble experienced by home owners is the water on the floor being rejected by the floor drain. One of its causes is the presence of sand and other objectionable wastes accumulated inside the P-trap. Sand and dirt are accumulated inside the floor drain gradually when cleaning the floor. And to remove this accumulated sand inside the P-trap is a real problem which has started from the time when: 1. The plumber failed to anticipate this problem. He installed a 50 mm or 2 inches Ptrap, which is too small for a human hand or tools to clean. 2. The P-trap installed might have been too deep below the floor line despite of its being small in size. Trouble in the plumbing installation is very certain to happen and therefore, must be anticipated. The plumbing layout as Built-in Plan must be kept for future reference in case of trouble. Without the Built-in Plan, hit and miss repair would be very difficult and costly. Experienced plumber will not install P-trap smaller than 75 mm diameter on floor drain. More so, when it will be installed underground or embedded in concrete slab. The difference in cost between a 50 and 75 mm waste pipe for a short distance floor drain and P-trap is immaterial, compared with the risk and inconveniences that will be encountered in case of drain trouble. Experienced plumber specifies floor drain not less than 75 mm. 8.10 Reminders in Installing Floor Drain 1. Floor drain is usually installed on basement floor, near the heating equipment, below the kitchen sink, vicinity of the laundry. 2. The 75 mm or 3” P-trap is recommended minimum size for floor drain. It should be installed not more than 20 centimetres below the floor line. 3. The P-trap should be Deep Seal Type. 4. The low inlet hub pattern P-trap is commonly used as floor drain. 8.11 Basement Floor Drain The National Plumbing Code on Basement Floor Drain provides that: “Cellar or basement floor drains shall connect into a trap so constructed that it can readily be cleaned and of a size to serve the purpose efficiently for which it is intended. The drain outlet should be so located that it is at all times in full view. When subjected to back flow pressure, such drains shall be equipped with an adequate Back Flow Valve.” Engineering Utilities 2 17 8.12 Yard Catch Basin Yard catch basin is defined as a receptacle used to catch surface water drained from cemented courts, driveways, and yards. It could be a terminal for drain tile installations used to drain water from athletic fields. 8.13 Garage Catch Basin Garage Catch Basin is a device designed to convey wastes from garage, wash rack, grease pits and repair floors into the house drain. Wastes coming from these areas contain objectionable elements like grease, oil, girt and gasoline that are detrimental to the drainage installation as well as the sewage disposal system. These sediments cause stoppage and effect the operation of the sewage disposal plant. Oil and grease adhere to the mechanical devices used in the treatment of sewage. These kinds of wastes may reduce the bacterial activity necessary to the process. The function of garage basin is to retain these noxious materials and discharge the associated water into the house drain. The efficiency of the garage catch basin depends on how it is regularly cleaned. 8.14 Grease Basins Most stoppage in the plumbing system were found to be caused by grease and oil contained in the waste discharges. This is more prevalent in large kitchens serving hotels, dining rooms, clubhouses and restaurants. To overcome this problem, a device known as a grease trap is installed on the waste line. The efficiency of a grease trap is dependent on the attention given to it. Removal of the grease is done regularly to obtain the full benefit of the device. But removal of the grease is a disagreeable work, and in most instances is done only when the trap ceases to function. Big establishments clean their grease trap almost daily. 8.14.1 Installing the Grease Basin 1. The grease trap shall be installed as close to the fixtures as possible. More than one fixture can discharge into the same trap, provided that the waste pipe is not very long and the trap has sufficient size. 2. A grease trap placed on the ground is earth cooled. Earth-cooled Grease Trap is used on large installation and is most desirable type. 3. The basin width should not be less than 60 centimetres. The length should be from 3 to 4 times its width to attain a smooth and non-agitated flow. 4. The minimum depth of concrete grease trap should not be less than 120 cm below the outlet invert. 5. The size of grease trap is measured through the volume of fixture units to be discharged. It could be sized according to the number of meals served estimated at 4 to 5 gallons of liquid capacity for each meal. Experienced sanitarians estimated double the actual volume of waste to which the trap will serve. Reference: Plumbing Design and Estimate, 2 nd Edition by Max B. Fajardo, Jr. Engineering Utilities 2 18  CHAPTER 9 THE HOUSE SEWER House Sewer is defined as, that portion of the horizontal drainage system, which starts from the outer face of the building and terminate at the main sewer in the street or septic tank. Other code defined House Sewer as, that portion of the horizontal drainage system, which starts 90 centimeters from the outer face of the building. House sewer is sometimes called the Building Sewer. The Main Sewer line is financed and maintained by the government. Those houses along the street with main sewer line are required to connect their house sewers to the public sewer line. The efficiency of a drainage installation depends upon the performance of the house sewer, and efficiency would increase by making good connection to the main. 9.1 House Sewer Connection to Main Sewer The house Sewer is connected to the main sewer by boring a small hole through the concrete pipe, using a sharpened steel chisel or electric drill. The hole is gradually enlarged to receive the sleeve. Extra care should be exercised not to break the inside wall of the main sewer. The House Sewer pipe is connected to the Main Sewer entering at 45 degrees angle or directly from the top. 9.2 General Conditions in Installing Sewer Pipes 1. Secure permits from the sewerage authority. 2. Verify the depth of the house drain outlet. 3. Determine the depth of the connection with the main sewer in the street and the grade of the house sewer. 4. The depth is found by measuring the length of the longest branch of the house drain multiplied by the pre-planned pitch per meter. 5. Add the required 30 cm ground coverings from the top of concrete floor or 40 centimeters of ground covering without concrete floor. 6. Verify the depth of the connection to be made with main sewer. Remove the manhole cover on both ends. Measure the depth using a meter tape or stick. 7. The grade of the house sewer could be found through the difference between the House Sewer and the depth of the main sewer. A levelling instrument will give satisfactory result. Additional grade can be made with the use of 1/8 bend considered as the most practical method of establishing grade. 9.3 Size of the House Sewer The size of the house sewer for residential connection to the main or septic tank has been established by sanitary authorities, based on their records of installation tests, and mathematical conclusions. The old practice is to use 150 mm or 6 inches diameter cement or vitrified clay pipe for house sewer. If plastic pipe or its interior surface texture equivalent is used, the diameter can be reduced to 100 mm diameter, subject to the standard rules, promulgated by the National Plumbing Code. In selecting sewer pipe for hotels, apartment houses, commercial and industrial buildings, the total discharges in terms of fixture unit are considered. Likewise, the overlapping of discharges and the simultaneous use of the fixtures are also included in the calculations. Reference: Plumbing Design and Estimate, 2 nd Edition by Max B. Fajardo, Jr. Engineering Utilities 2 19  CHAPTER 10 THE STORM DRAIN Storm Drain is that unit of the plumbing system that conveys rain or storm water to a suitable terminal. Storm water is normally discharged into street gutter conveyed by public drain system and carried to some natural drainage terminal like canals, rivers, lakes and the like. As general rule, storm drain is not permitted to discharge into a septic tank or to the main sewer line. The collection and disposal of storm water is an important phase of plumbing system that should not be ignored, otherwise, water coming from the roof it not properly diverted might create problems like: 1. Settlement of the structure cause by erosion or washing away the soil from the foundation. 2. Subjecting the basement floor and walls to unnecessary ground water pressure and possible leakage. 3. Rundown water may create walls and window leakage. 4. Water may spill on people passing by or approaching entry door. 5. Erode the surrounding grounds and cause disfiguring of the landscape areas. The disposal of storm water has become a major concern of the Local and National Government. Large amount of appropriation is regularly incorporated in the annual budget for drainage purposes. Among the government’s priority program on infrastructure, is toward flood control. The trend is to provide a storm sewer line, to serve not only the commercial and industrial establishments, but also residential houses in disposing off storm water. Laws and Ordinances were passed making the connections of storm drain to the storm sewer line compulsory. Splash Pan is a collector of water coming down from the downspout leading the accumulated water away from the house at a relatively low rate of flow. 10.1 Classification of Storm Drain 1. The Inside Storm Drain 2. Outside Storm Drain 3. Overhead Storm Drain The Inside Storm Drain is sometimes located under the basement floor or within the walls of the building. This type of storm drain is commonly found in buildings constructed along congested business district, or building that occupies the entire frontage of the lot. The drain pipe is laid under the floors or walls of the structure. For large building, storm drains are laid in two or more lines to convey not only the water coming from the roof, but also those waters accumulated from the inside court or open areas towards the street gutter or public storm drain. The Outside Storm Drain is installed outside the foundation wall of the building. This type of drainage is possible on location where the lot is not totally occupied by the building. The Overhead Storm Drain is adopted when the street drainage is higher in elevation than the basement floor of the building. The purpose is to avail of the gravity flow of water. The pipe is well fitted and suspended inside the ceiling by suitable hangers spaced at closer intervals. 10.1.1 Size of Storm Drain The size of Storm Drain is determined under the following considerations: 1. Gauging the rainfall over a given period, whether it is constant or exceedingly heavy shower of short duration. 2. Consider the varying roof areas, the slope, and the distance of waster travelled before it reaches the conductors of the roof. 3. Water drain faster on high pitch roof. Hence, requires a larger drainage pipe than that of a flat roof. Engineering Utilities 2 20  4. The height of the building, contribute largely to the velocity of water falling inside a vertical pipe conductor. The velocity fall accelerate the flow of water entering into the storm drain. Size of Storm Drain Table Dia. of Pipe Maximum Drained Roof Area mm inch 2% Slope 3% Slope 4% Slope 75 3 114 142 170 100 4 242 315 388 125 5 438 566 694 150 6 700 903 1,105 200 8 1,463 1,888 2,313 250 10 2,563 3,309 4,055 300 12 4,100 5,290 6,480 350 14 5,576 7,203 8,830 5. The use of improper fittings and short offsets that will affect the flow of water must be avoided. The conservative estimate of maximum rainfall in the Philippines is about 20 mm in a 5 minutes interval. Using this data, the approximate volume of water that will be accumulated on the roof in one minute can be readily computed using Size of Storm Drain Table. Illustration 10 - 1: What size of storm drain is adequate to serve a roof having a slope of 2% with general dimensions of 20 x 30 meters? Solution: 1. Solve for the roof area. Area = 20 x 30 A = 600 sq.m. 2. Refer to Size of Storm Drain Table, under 2% slope, 600 sq.m. is within the limit of 700 sq.m. roof area which could be served effectively by a 150 mm pipe diameter. 10.2 Grade and Change of Direction The storm drain is installed providing a slope of not more than 2% per meter run. A combination of Y and 1/8 bend or a long radius fitting is appropriate for any change in direction. 10.3 Roof Leader Roof Leader is popularly known as water conductor or downspout either concealed or exposed type. It connects the roof terminal to the storm drain. The size of roof leader can be found easily with the aid of the table presented below (Size of Roof Gutter and Roof Leader). Size of Roof Gutter and Roof Leader Table Area of Roof (sq.m.) Gutter Top Dimension Roof Leader Diameter (mm) (mm) 1 to 10 75 38 11 to 25 100 50 26 to 75 100 75 76 to 165 125 90 166 to 335 150 100 336 to 510 200 125 Engineering Utilities 2 21  511 5o 900 250 150 Illustration 10 - 2: How large is a downspout required to drain the roof with a general dimensions as 10m x 20m. Solution: 1. Find the area of roof – A 10 x 20 = 200 sq.m. 2. Refer to Size of Roof Gutter and Roof Leader Table, under column 1; the 200 sq. m. roof area is within the limit of 166 to 335. Thus, specify 100 mm or 4” diameter downspout. 3. Find the area of roof – B 8 x 20 = 160 sq.m. 4. Refer to Size of Roof Gutter and Roof Leader Table. The value of 160 sq.m. requires a 75 mm (3”) roof leader. 5. Therefore, specify a 75 mm pipe diameter. Comments: 1. From illustration above, it appears that roof A requires a 100 mm diameter pipe and 75 mm for roof B. If only one roof leader will be installed in each roof, considering the 20 meters length of the gutter, the rainwater has to travel a long way before it reaches the roof terminal. Under such condition, the gutter might overloaded and overflow is likely to occur. 2. The standard practice is to provide two or more terminals for roof leader to avoid clogging and overflow. The found size of the pipe if installed on two terminals would be oversized and expensive. Thus it is necessary to select two smaller pipes with a hole area equivalent to 100 mm and 75 mm diameter effectively. Solution: 1. The 100 mm or 4” diameter as found has a cross sectional area of: Area of a circle = π x D² Area = π x (4)² = 12.56 sq.in. 2. Divide into two terminals = 6.28 sq.in. 3. The gross sectional area of a 75 mm (3”) is 7.06 in² greater than 6.28. Therefore, specify 2 pcs. 75 mm diameter pipe. Second Solution 1. Area of the roof A = 200 sq.m. 2. Divide by 2 terminals = 100 sq.m. 3. Refer to Size of Roof Gutter and Roof Leader Table. The 100 sq.m. area is within the parameter of 76 and 165 sq.m. therefore, specify 2 pcs 75 mm diameter pipe. 4. For roof area B = 160 sq.m. 5. Divide by 2 terminals = 80 sq.m. 6. Refer to Size of Roof Gutter and Roof Leader Table. 75 mm pipe is sufficient. 7. Specify 2 pcs. 75 mm downspout for roof B. Reference: Plumbing Design and Estimate, 2 nd Edition by Max B. Fajardo, Jr. Engineering Utilities 2 22  MODULE 2: LIFE SAFETY SYSTEMS IN BUILDINGS CHAPTER 1 1.1 FIRE PROTECTION IN BUILDING The protection of building structures from the hazards of fire is one utmost concern of the government. Hence, for a continued citizens awareness of damages brought by fire to life and property, the month of March was declared as fire prevention month. Planners and builders have their own contributions in this campaign, by making their plans and constructions conform to the Fire Code Requirements. The owner on the other hand, is much more concern of his investment protection. However, despite the advancement in fire protection technology, fire is still common occurrence in buildings of all types. Records showed that the loss of life and damages to property is considerably enormous in every incident of fire. Modern design and construction techniques, did not escape the blame for allegedly having increased the potential of fire, especially, in tall buildings attributed to the following: 1. Light material construction methods do not offer inherent protection against fire unlike the cement plaster or concrete. 2. Non-integrally constructed floors and walls provide fuse for fire and smoke. 3. False ceiling containing electrical, and other services, are hidden locations where fire can start unnoticed. 4. Punched-hole for installation of telephone and other related services violates the design structural integrity. 5. The central air conditioning system can serve as passage for smoke. 6. The usage of plastic materials for trim and covering of interior surfaces create potential ignition for fire and smoke. 7. Furniture style and materials plus interior designs could ignite or fuel fire. Classification of Fires Class A – fires of ordinary combustible materials such as wood, cloth, paper, rubber, and many plastics. Class B – Fires in flammable liquids, oils, greases, tars, oil-based paints, lacquers, and flammable gases Class C – fires that involve energized electrical equipment. In such fires, it is important that the extinguishing medium not be a conductor of electricity. Therefore, water as a medium is not advisable. Class D – fires in combustible metals such as magnesium, titanium, zirconium, sodium, lithium, and potassium. Planning for Fire Protection One of the many responsibilities given to Architects and Engineers by their License to Practice is the protection of building against loss of life and damage to property from fire. The owner on the other hand, is very much concerned with the preservation of the structure and its contents from the destructive effect of fire. As part of their responsibilities, planners and builders should look into all the facets of possible problems that maybe encounter including fire safety. Tall building present variety of unique problems, more particularly on fire safety must be addressed at the very start of the planning stage because the belief that these imposing structures of modern technology are totally immune to fatal fire is hard to accept. To some extent, a useful way to consider tall building is to define a high-rise building in terms of fire protection. Engineering Utilities 2 23 Fire Protection Problems on Tall Buildings are: 1. Too high to be completely accessible to firefighting equipment from the ground. 2. Too high to make a complete evacuation of the occupants. 3. Tall enough to make possible chimney for air and smoke passage. The National Fire Protection Association maintained a comprehensive set of standard rules in planning to minimize fire hazard. The guidelines include the equipment design for firefighting which is mandatory. The Fire Code on the other hand, considers the building density in the locality and the flammability of the structures and its contents. It also improves the following requirements: 1. Fire resistance of the building and its contents 2. Limitation of volume to adjacent vulnerable buildings. 3. Exits and fire tower stairs 4. Protection against defective electrical system 5. Lightning protection 6. Detection and alarm systems 7. Automatic sprinkler systems 8. Standpipe and hose systems 9. Automatic smoke and heat venting 10. Smoke and heat shafts 11. Control of air conditioning ducts 12. Communication in high rise buildings 13. Elevator control 14. Fire command station in tall buildings The scope of this Module on LIFE SAFETY SYSTEMS IN BUILDINGS on Fire Protection in Building is limited only to the topics that are related to the subject of plumbing. Discussions will be limited to the following: 1. Water and water supply for firefighting 2. Water pumping systems 3. Standpipe and hoses 4. Sprinkler systems Fire suppression is achieved by cooling the combustible material to below its ignition temperature or by preventing oxygen from interacting with the combustible material. The most popular medium for building fire suppression is water, which is readily available and relatively low in cost. It cools, smothers, emulsifies and dilutes. As it turns to vapour, it removes 970BTU/lb of latent heat, and its volume increases 1700 times –a process that helps push away the oxygen needed by the fire. Being the most popular medium readily available and relatively low in cost for fire fighting, water has some disadvantages and is listed as follows: 1. Damages most contents of the building. 2. Conducts electricity readily as stream. 3. Flammable oils float on its surface as it continues to burn. 4. As it vaporizes rapidly, it can harm people, especially fire fighters. Water and Water Supply Water is the number one enemy of ire. Even with the latest modern and sophisticated firefighting equipment, gadgets, tools and other concoctions, water is still an essential requirement in combating fire. Engineering Utilities 2 24  On high rise building, water is supplied through: 1. Elevated water tank or 2. Underground reservoir Elevated Water Tank The Elevated Water Tank is a traditional design of storing water in an elevated reservoir for the following purposes: 1. To supply a constant pressure of water in the distribution lines. 2. To store sufficient water to balance the supply from the demand. 3. To prevent excessive starting and stopping of the pump. 4. To provide dependable supply for fire reserve. The Elevated Water Tank has also the following disadvantages: 1. Unsightly appearance. 2. High cost of construction. 3. Requires massive structure and foundation for its tremendous weight. Underground Water Reservoir The underground water reservoir is one alternate to replace the elevated water tank. It is a reinforced concrete structure constructed on one side of the building, provided with a small vent rising above the ground. The reservoir is covered with earth from 60 to 90 centimeters blended with the lawn and landscape shrubbery. It completely eliminates the problem of unsightly appearance and weight. Cost comparison would be difficult because of the number of factors involved. The savings for materials and other construction costs may be sufficient to cover the cost of an automatic pumping system. The idea of storing large volume of water for a protracted fire fighting is practical. A 30 minutes supply that could be used by the building personnel, in the meantime that the fire department has not arrived yet, is sufficient. Thereafter, the trained personnel of the fire department will take over with their own water supply or drawn from the street fire hydrant. Other than water, fire suppression medium can be foam, chemicals, halogenated gas, etc. These can be applied by the use of portable extinguisher, standpipe-and-hose, and manual or automatic sprinkler system. Standby Power In case of fire incidence, power supply in the building is automatically cut off which could be a tragedy. A standby diesel powered generator is a must. This unit and its fuel stock are separately housed in a fire resistant enclosure sufficiently away from the possible location of fire in the building. The Up-Feed Pumping System The Up-Feed Pumping System provides a continuous flow of water from the deep well through the domestic and fire reservoir. The continuous flow of water prevents it from becoming stagnant and rancid. The fire reservoir has the priority over the domestic reservoir by means of a simple weir. Even if the domestic reservoir is totally empty, the fire reservoir would remain full of water. A small 20 gallons per minute jockey pump will supply the necessary pressure for the sprinkler system, and consequently, a signal from the sprinkler system will start the 750 gpm (gallons per minute) main pump. If this pump becomes inadequate for the demand, a diesel engine driven pump of equal capacity will automatically takes over. The sensing units which control the operations of the pumps are: 1. The Bubble Control Units in each of the two reservoirs. 2. The Dual Control Unit that regulates the supply for the pressure tank. Engineering Utilities 2 25  These controls are connected to a large central cabinet underground pump room adjacent the reservoir. Hydro-pneumatic Tank A hydro-pneumatic tank is used to store air under pressure that will balance out- surge from the two domestic pumps and reduce the frequently starting, and stopping of the motor. It is an improvement of the closed system, where several pumps are sequences automatically to supply an even pressure. It has the advantage of using only two pumps when necessary. One disadvantage of this system is the difficulty in maintaining the ratio of 60% air to 40% water. Water from deep well to the tank becomes air bound as water stored therein gives up its absorbed air. The dual control installation eliminates the need for manual adjustment of this 60% to 40% ratio by employing two sensing devices within a single control. A drop air pressure inside the tank will send signals to start the pump, and the rise of water level, automatically send signals to stop the motor. How the Control System Operates: 1. For correct time delay through the motor driven relays, the signal from the dual control and the double control units are processed in the central cabinet. 2. The central control system alternates the pumps to give them even wear, or run them together as demand requires. 3. In case of low suction, the control system automatically shut off to prevent motor damage. 4. At the same time after it shut off, it relays the alarm signal to the office of the Maintenance Engineer indicating the location of the trouble 5. The system could run without human attendance to satisfy the heavy demand of air conditioning, domestic water supply, and fire control. The Standpipe and Hose What is a Standpipe and Hose System? The Standpipe is a pipe installed in buildings not as part of the water supply or disposal system, but primarily, for use as water conveyance in case of fire. Standpipe-and-hose systems are a series of pipes and valves which connect a water supply to hose connections and allied equipment that are designed to provide a pre-piped water system for fire suppression purposes for building occupants or the fire department. They are provided with separate water reserve, up-feed pumping, or fire department connections. The Fire hose is always located near the stairs for use by firemen in case of fire. It is incased in glass cabinets with the following label: “Break Glass in Case of Fire.” Standpipe-and-hose systems are a series of pipes and valves which connect a water supply to hose connections and allied equipment that are designed to provide a pre-piped water system for fire suppression purposes for building occupants or the fire department. The Standpipe and Fire Hose Functions as Follows: 1. Upon arrival of the firemen, the standpipe Siamese twin is immediately connected to the street fire hydrant or to any other water source by their fire hose. 2. The firemen would immediately goes up the building and connect their fire hose to the standpipe, freeing them from the inconvenience of carrying their hose to the upper floor of the building. 3. With the standpipe and hose, the firemen were provided with an ever ready fire fighting tools and equipment that saves time and effort which may spell the difference in saving life and property. 4. The length of the firemen hose is limited to a certain height, but because of the standpipe provision, the upper most floor of a tall building, could be reached by the fire fighters. Engineering Utilities 2 26 Classification of Standpipe Systems by their Usage Class I – for heavy stream applications. Class II – as “first aid fire appliances” Class III – which has the features of both Class I and Class II Five Types of Standpipes 1. Automatic-Wet standpipe, filled with water at all times, is connected to a permanent water supply that is capable of meeting flow and pressure requirements. Engineering Utilities 2 27  2. Manual-Wet standpipe, filled with water at all times, is connected to a water supply that is not capable of meeting flow and pressure requirements. The purpose of the water supply is to maintain water within the system, thus reducing the time it takes to get water to the hose station outlets. Manual-wet standpipe systems need water from a fire department pumper (or the like) to be pumped into the system in order to meet flow and pressure requirements. 3. Automatic-Dry standpipe, filled with pressurized air, is connected to a permanent water supply that is capable of meeting flow and pressure requirements. It uses a device, such as a dry pipe valve, to admit water into the system piping automatically upon the opening of a hose valve. 4. Semi-automatic-Dry standpipe, with empty pipe, is connected to a permanent water supply that is capable of meeting flow and pressure requirements. It uses a device, such as a deluge valve, to admit water into the system piping upon activation of a remote control device located at a hose connection. A remote control activation device shall be provided at each hose connection. 5. Manual-Dry standpipe, with empty pipe, is not connected to a water supply. Manualdry standpipe systems need water from a fire department pumper (or the like) to be pumped into the system in order to meet flow and pressure requirements. Standpipe-and-Hose Systems Design Factors 1. Minimum flow rates for standpipes and fire hoses. 2. Minimum pressure 3. Maximum pressure Preliminary Design Guidelines 1. Class I and III standpipes not exceeding 30m in height must be a minimum of 100mm nominal pipe size. 2. Class I and III standpipes exceeding 30m in height must be a minimum of 150mm nominal pipe size (although the topmost 30m may be a minimum of 100mm nominal pipe size). 3. For combined standpipe and sprinkler systems regardless of height, a minimum of 150mm nominal pipe size is required. 4. For Class I and III systems, a minimum hose pressure of 100psi is required. Maximum hose pressure (also for sprinklers) is 175psi. 5. Water from a public system or from an alternative source shall be adequate for a minimum of duration of 30 minutes. 6. Fire standpipes and their hoses (for full-scale fire fighting) are to be located on the landings of stairs, from which personnel or fire fighters can approach a fire with charged hoses. 7. Class I and III standpipes shall be sized for 500gpm for the first standpipe and 250gpm for each additional standpipe, but normally not more than 1250gpm for the total system, including the sprinkler water demand for buildings that have a limitedarea sprinkler system. 8. Class II standpipe sizes shall be based on 100gpm for each riser and not more than 500gpm for the total system. 9. For office buildings, multi-family dwellings, one or two family dwellings, and with an automatic sprinkler system, the flow rate may be sized for 250gpm for each standpipe and not more than 750gpm for all standpipes. The demand for the automatic sprinkler system shall be calculated independently. 10. There shall be fire hose connections on each side of fire enclosures so that hose connections can be made inside or outside of the stairway enclosure. 11. Fire department connection shall be provided outside of the building. A minimum of two connections shall be installed for high-rise buildings. Hoses may be installed on racks, on reels, or in cabinets containing portable fire extinguishers and tools. The cabinet door will be latched. 12. A water flow alarm shall be provided for the automatic and semi-automatic standpipe systems. Valves shall be provided for isolation of piping, prevention of back pressure and shutoff purposes. All valves shall indicate, at a distance, whether they are open or close. Isolation valves shall be locked in open position. Engineering Utilities 2 28  13. Each standpipe shall be provided with a means of draining. The drainpipe shall be 20mm for a 50mm standpipe and up to 50mm for a 100mm or larger standpipe. Standpipes with pressure-regulating devices shall have a 75mm drainpipe. 14. Standpipe system shall be limited to vertical height of 84 meters. For high-rise buildings, separate standpipe systems shall be provide for each 84 meters of vertical height 15. Standpipe risers at some stairways may be omitted if: All parts of the building can be reached by a 9-meter “hose stream” (water stream) at the end of a 30-meter fire hose from other risers. (Note: The distance shall be the actual developed length measured along a path of travel originating from the hose connection), or All parts of the building are within 122 meters from access to fire department vehicles and not more than 61meters from another hose connection. 16. As a general rule, standpipe systems installed in all buildings shall be of the wet variety, except when the highest floor of the building is: Lower than 23 meters, or Lower than 45 meters and the building is protected by an automatic sprinkler system, or Lower than 45 meters and the building is an open parking structure Engineering Utilities 2 29 Standpipe-and-hose System Components Engineering Utilities 2 30 Automatic Sprinkler System What is an Automatic Sprinkler System? Automatic Sprinkler System is an integrated fire suppression system consisting of a water supply, a network of pipes, sprinkler heads, and other components to provide automatic fire suppression in areas of a building where the temperature or smoke has reached a predetermined level. Types of Automatic Sprinkler Systems 1. Wet-pipe system Most common type, have water, under pressure, in the pipes at all times Water is supplied either from a roof tank or from a ground level tank and automatic pump system that maintains pressure in the system Each sprinkler head acts individually, i.e., sprinkler heads in the affected area only are activated Engineering Utilities 2 31 2. Dry-pipe System These systems are filled with compressed air (or nitrogen) rather than with water. Used in unheated areas, cold-storage areas including loading docks As soon as sprinkler head opens, the compressed air rushes out, allowing water to enter the formerly dry-pipe system through a dry-pipe valve. It then functions like a wet-pipe system A maximum system capacity of 2,840 liters is recommended Require pitching of all piping to allow thorough drainage after usage Engineering Utilities 2 32 Engineering Utilities 2 33 Types of Automatic Sprinkler Systems 1. Deluge System This system is a dry-pipe system that has open sprinkler heads. Responds to abnormally high temperature anywhere in the protected area by opening a deluge valve that supplies water to all the heads. As a result, all sprinkler heads operate simultaneously. The purpose of the design is to prevent the extremely rapid spread of fire, as in buildings with highly flammable materials. It is also used where fire can produce noxious or poisonous fumes, as in chemical plants. Engineering Utilities 2 34 2. Pre-action System This system is a dry-pipe system filled with air and having a supplemental detection system installed in the area. The detection system may be sensitive to either temperature or the density of smoke. Actuation of the detection system opens a valve that permits water to enter into the system and to be discharged from any of the sprinkler heads that may be open. Used in areas where water damage may be extremely detrimental to the property or may interfere with business operations. Engineering Utilities 2 35 3. Circulating Closed-loop System This system is a wet-pipe system that uses rather large sprinkler piping to circulate water for heating and cooling operations of the HVAC system. Water is not removed from the system, merely circulated. Water temperature must not exceed 49oC or fall below 4oC. The operation of the HVAC system should not interfere with the water flow from the sprinkler when the automatic sprinkler function is activated. Sprinkler Piping Types 1. Ferrous piping (welded and seamless) –can either be black steel, galvanized, or wrought steel pipe that are manufactured in various wall thickness. Most common for sprinkler systems are schedules 40, 30 and 10. NFPA Standard 13 notes minimum wall thickness for steel pipe depending on the method of joining the pipe. 2. Copper tube (drawn and seamless) Engineering Utilities 2 36 3. Non-metallic [polybutylene and chlorinated polyvinyl chlorinated (cPVC)] piping– lightweight and has favourable hydraulic characteristics for water flow. Special installation requirements are as follows: –For use in light hazard occupancies only –Limited to indoor wet-pipe systems –Must have a protective membrane –Can be exposed when quick-response or residential sprinklers are installed Major Sprinkler System Components Engineering Utilities 2 37 Engineering Utilities 2 38 Components of an Automatic Fire Sprinkler System 1. Stop Valve-The Stop Valve is used to isolate the water supply, it may also be called the isolating valve. It is often painted RED in colour with a large black circular handle, and is locked in the OPEN position, allowing the free flow of water. The stop valve is used to isolate (stop) the water supply coming in to the fire sprinkler system. 2. Valve Monitor that is used to monitor the state (open or closed) of theStop Valve. The water within an au