Sanitary Drainage System PDF

LECTURE 4 Sanitary Drainage System Sanitary Piping Layout The pipes should take the shortest possible route to the house sewer or the terminating point of the Sanitary system Control components such as clean-outs, traps, and vents, should be located strategically so as to ensure efficient circulatio...

LECTURE 4 Sanitary Drainage System Sanitary Piping Layout The pipes should take the shortest possible route to the house sewer or the terminating point of the Sanitary system Control components such as clean-outs, traps, and vents, should be located strategically so as to ensure efficient circulation Waste Collection System Ventilation System Essential Parts of the Sanitary Drainage System Waste Pipe- conveys only wastewater or liquid waste free of fecal matter Vent Pipe- used for ensuring the circulation of air in a plumbing system and for relieving the negative pressure exerted on trap seals. Trap-a fitting or device designed and constructed to provide, when properly vented, a liquid seal which prevents the backflow of foul air or methane gas without materially affecting the flow of sewage or wastewater through it. Stack-the vertical main of a system of soil, waste or vent pipings extending through one or more stories and extended thru the roof. Branch-any part of the piping system other than a main, riser or stack. Essential Parts of the Sanitary Drainage System House/Building Drain-part of the lowest horizontal piping of a plumbing system which receives the discharges from the soil, waste and other drainage pipes inside of a building and conveys it to the house sewer outside of the building. House/Building Sewer-extends from the house drain at a point 0.60 meters from the outside face of the foundation wall of a building to the junction with the street sewer or to any point of discharge, and conveying the drainage of one building site. Principles of Waste & Soil (EXCRETA) Pipes Roughing-in Horizontal to Horizontal change in direction -use 45° wye branches, combination wye – 1/8 bend branches, or other approved fittings of equivalent sweep Vertical to Horizontal change in direction-45° wye branches or other approved fittings of equivalent sweep Horizontal to vertical change in direction ▪ Horizontal to vertical change in direction ▪ No fitting having more than one inlet at the same level shall be used (i.e., sanitary cross) ▪ Double sanitary tees may be used when the barrel of the fitting is at least two pipes (2) sizes larger than the largest inlet, (pipe sizes recognized for this purpose are 51, 64, 76, 89, 102, 114, 127, & 152 mm dia.) Sanitary Drainage Lines The size of waste pipes or soil pipes depend on the amount of waste it carries. A lavatory discharges 0.47 liters/sec or 28.3 liters/min (7.5 gallons per min or 1 cu ft per min), which is equivalent to the Fixture Unit (F.U.) The F.U. rating of plumbing fixtures is based on the size of required trap. Maximum Trap Loading Exception: On self-service laundries. Notes: 1. Capacity over 3.15 L/s shall be determined by the Administrative Authority. 2. For a continuous flow into a drainage system, such as from sump pump or ejector, air-conditioning equipment or similar devices, two (2) fixture units shall be allowed for every 0.063 L/s of flow. 3. 1 gpm = 0.063 L/s Discharge Capacity Minimum slope or pitch of horizontal drainage pipe – 2% or 20mm/m (¼” per foot). Exception: Where it is impracticable due to depth of street sewer, adverse structural features and irregular building plans, pipes 102 mm dia or larger may have a slope of not less than 1% or 10mm/m (1/8” per foot), approved by the Administrative Authority Traps & Interceptors Types of Permissible Traps: The Common P-Trap Used for lavatories, kitchen sinks, laundry tubs, & urinals Materials commonly used for the P-trap: nickel, chrome plated brass, Galvanized malleable copper, & PVC. The Deep Seal P-Trap Water seal is about twice the size of the common P-trap Used for extreme conditions because resealing quality is greater The Stand Trap Used for fixtures such as slop sinks that are usually built low in the ground, leaving very little space for a foundation & a trap Serves as a water seal & structural support for the fixture The Running Trap Types of Permissible Traps: The Drum Trap Used within the line of the house drain Has a large diameter (around 0.16 m) Used for fixtures that discharge large amount of water (bathtubs, shower or floor drains) Types of Prohibited Traps: Traps with movable parts or concealed interior partitions No fixtures shall be double-trapped The S-Trap ▪ Predecessor of P-traps ▪ Used before traps had to connect to a ventilation line Traps REQUIRED REQUIREMENTS: Each plumbing fixture, except those with integral traps, shall be separately trapped with an approved-type waterseal trap Only one trap shall be permitted on a trap arm (portion of a fixture drain between a trap and the vent) One trap, centrally located, may serve three single compartment sinks or laundry tubs or lavatories, adjacent to each other and in the same room, where their waste outlets are not more than 0.75 m apart. SIZE OF TRAPS: The trap shall be the same size as the trap arm to which it is connected. Each fixture trap shall have a trap seal of water of not less than 51 mm and not more than 102 mm (except where a deeper seal is found necessary by the Administrative Authority for special conditions.) Minimum sizes of traps for common plumbing fixtures INSTALLATION OF TRAPS: The vertical distance between a fixture outlet tailpiece and the trap weir shall not exceed 0.60 m in length. Horizontal Distance of Trap Arms Note: In no case shall the trap distance be less than 2 times the diameter of the trap arm. The developed length of the trap arm (measured from the top of closet ring to inner edge of vent ) of a water closet or similar fixture shall not exceed 1.8 m. For trap arm 76 mm dia or larger, a cleanout is required for a change of direction of greater than 22 ½ °. Clean-outs REQUIREMENTS: Clean-outs REQUIRED at the upper terminal of every horizontal sewer or waste line at each run of piping more than 15 meters (50 feet) in total developed length at every 15 m (50 ft) of total developed length or a fraction thereof additional clean-out shall be provided on a horizontal line with an aggregate offset angle exceeding 135° inside the building near the connection between the building drain and the building sewer or installed outside the building at the lower end of the building drain and extended to grade. Clean-outs NOT REQUIRED on a horizontal drain less than 1.5 m in length unless such line is serving sinks or urinals. on short horizontal drainage pipe installed at a slope of 72 deg or less from the vertical line (or at an angle of 1/5 bend) SIZE OF CLEAN-OUTS: Size of clean-out shall be in conformity with the size of pipe served Clean-Out Size INSTALLATION OF CLEAN-OUTS: Each clean-out shall be installed so it opens with the direction of flow or at right angles to the direction of flow except in the case of a wye branch. Each 90° clean-out extension shall be constructed from a wye fitting or an approved fitting of equivalent sweep. Each clean-out 51 mm or less shall have a front clearance of not less than 305 mm; those 51 mm or more shall have a front clearance of 450 mm. Clean-outs in underfloor piping shall be extended to or above finish floor or shall be extended outside the building when there is less than 450 mm vertical clearance or 750 horizontal clearance to the means of access. No underfloor clean-out for residential occupancies shall be located more than 6.1 m from an access door, trap door or crawl hole.