Plumbing Engineering Design Handbook Vol 2 2010 PDF

American Society of Plumbing Engineers Plumbing Engineering Design Handbook A Plumbing Engineer’s Guide to System Design and Specifications Volume 2 Plumbing Systems American Society of Plumbing Engineers 2980 S. River Road...

American Society of Plumbing Engineers Plumbing Engineering Design Handbook A Plumbing Engineer’s Guide to System Design and Specifications Volume 2 Plumbing Systems American Society of Plumbing Engineers 2980 S. River Road Des Plaines, IL 60018 The ASPE Plumbing Engineering Design Handbook is designed to provide accurate and authoritative information for the design and specification of plumbing systems. The publisher makes no guarantees or warranties, expressed or implied, regarding the data and infor- mation contained in this publication. All data and information are provided with the understanding that the publisher is not engaged in rendering legal, consulting, engineering, or other professional services. If legal, consulting, or engineering advice or other expert assistance is required, the services of a competent professional should be engaged. American Society of Plumbing Engineers 2980 S. River Road Des Plaines, IL 60018 (847) 296-0002 Fax: (847) 296-2963 E-mail: [email protected] Internet: www.aspe.org Copyright © 2010 by American Society of Plumbing Engineers All rights reserved, including rights of reproduction and use in any form or by any means, including the making of copies by any photographic process, or by any electronic or mechanical device, printed or written or oral, or recording for sound or visual reproduction, or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the publisher. ISBN 978-1-891255-17-5 Printed in China 10   9   8   7   6   5   4   3   2   1 Plumbing Engineering Design Handbook Volume 2 Plumbing Systems Volume 2 Chair: James Rodgers, CPD Volume 2 Coordinator: Sarah A. Balz, PE, CPD, LEED AP Editor: Gretchen Pienta Graphic Designer: Rachel L. Boger CONTRIBUTORS Chapter 1 Chapter 7 Sanitary Drainage Systems Fuel Gas Piping Systems Kenneth M. Grabske Dennis F. Richards Jr., CPD Chapter 2 Chapter 8 On-site Wastewater Reuse and Storm Water Private On-site Wastewater Treatment Harvesting Systems Lynita M. Docken Robert M. Mutsch, PE, LEED AP Tom Braun Bruce Meiners Chapter 9 Private Water Wells Chapter 3 James M. Delain, PE Vents and Venting Systems Steven P. Skattebo, PE Chapter 10 Vacuum Systems Chapter 4 Sarah A. Balz, PE, CPD, LEED AP Storm Drainage Systems Lynita M. Docken Chapter 11 Tom Braun Water Treatment, Conditioning, Bruce Meiners and Purification Dennis F. Richards Jr., CPD Chapter 5 Cold Water Systems Chapter 12 Harold L. Olsen, PE Special Waste Drainage Systems Sarah A. Balz, PE, CPD, LEED AP Chapter 6 Domestic Water Heating Systems Thomas J. Breu, PE, CPD, LEED AP TECHNICAL REVIEWERS James A. Brune, PE, CPD Stephen Jerry McDanal, CPD, CET, FASPE Michael Frankel James T. Zebrowski, PE, CPD William F. Hughes Jr., CPD, LEED AP  About ASPE The American Society of Plumbing Engineers (ASPE) is the international organization for professionals skilled in the design and specification of plumbing systems. ASPE is dedicated to the advancement of the science of plumbing engineering, to the professional growth and advancement of its members, and to the health, welfare, and safety of the public. The Society disseminates technical data and information, sponsors activities that facilitate interaction with fellow professionals, and, through research and education programs, expands the base of knowledge of the plumbing engineering industry. ASPE members are leaders in innovative plumbing design, effective materials and energy use, and the application of advanced techniques from around the world. Worldwide Membership — ASPE was founded in 1964 and currently has 6,500 members. Spanning the globe, members are located in the United States, Canada, Asia, Mexico, South America, the South Pacific, Australia, and Europe. They represent an extensive network of experienced engineers, designers, contractors, educators, code officials, and manufacturers interested in furthering their careers, their profession, and the industry. ASPE is at the forefront of technology. In addition, ASPE represents members and promotes the profession among all segments of the construction industry. ASPE Membership Communication — All members belong to ASPE worldwide and have the opportunity to belong and participate in one of the 61 state, provincial or local chapters throughout the U.S. and Canada. ASPE chapters provide the major communication links and the first line of services and programs for the individual member. Communications with the membership is enhanced through the Society’s magazine, Plumbing Systems and Design, the newsletter ASPE Report, which is incorporated as part of the magazine, and the e-newsletter "ASPE Pipeline." Technical Publications — The Society maintains a comprehensive publishing program, spearheaded by the profession’s basic reference text, the ASPE Plumbing Engineering Design Handbook. The Plumbing Engineering Design Handbook, encompassing approximately 50 chapters in four volumes, provides comprehensive details of the accepted practices and design criteria used in the field of plumbing engineering. Recent additions to ASPE’s published library of professional technical manuals and handbooks include the Plumbineering Dictionary, Engineered Plumbing Design II, and The Hunter Papers. Convention and Technical Symposium — The Society hosts biennial Conventions in even-numbered years and Technical Symposia in odd-numbered years to allow professional plumbing engineers and designers to improve their skills, learn original concepts, and make important networking contacts to help them stay abreast of current trends and technologies. In conjunction with each Convention there is an Engineered Plumbing Exposition, the greatest, largest gathering of plumbing engineering and design products, equipment, and services. Everything from pipes to pumps to fixtures, from compressors to computers to consulting services is on display, giving engineers and specifiers the opportunity to view the newest and most innovative materials and equipment available to them. Certified in Plumbing Design — ASPE sponsors a national certification program for engineers and designers of plumbing systems, which carries the designation “Certified in Plumbing Design” or CPD. The certification program provides the profession, the plumbing industry, and the general public with a single, comprehensive qualification of professional competence for engineers and designers of plumbing systems. The CPD, designed exclusively by and for plumbing engineers, tests hundreds of engineers and designers at centers throughout the United States biennially. Created to provide a single, uniform national credential in the field of engineered plumbing systems, the CPD program is not in any way connected to state-regulated Professional Engineer (P.E.) registration. ASPE Research Foundation — The ASPE Research Foundation, established in 1976, is the only independent, impartial organization involved in plumbing engineering and design research. The science of plumbing engineering affects everything… from the quality of our drinking water to the conservation of our water resources to the building codes for plumbing systems. Our lives are impacted daily by the advances made in plumbing engineering technology through the Foundation’s research and development.  American Society of Plumbing Engineers Plumbing Engineering Design Handbook (4 Volumes — 47 Chapters) Volume 1 Fundamentals of Plumbing Engineering (Revised 2009) Chapter 1 Formulas, Symbols, and Terminology 2 Standards for Plumbing Materials and Equipment 3 Specifications 4 Plumbing Cost Estimates 5 Job Preparation, Drawings, and Field Checklists 6 Plumbing for People with Disabilities 7 Energy and Resource Conservation in Plumbing Systems 8 Corrosion 9 Seismic Protection of Plumbing Systems 10 Acoustics in Plumbing 11 Basics of Value Engineering 12 Ensuring High-quality Plumbing Installations 13 Existing Building Job Preparation and Condition Survey Volume 3 Special Plumbing Systems (Revision date: 2011) Chapter 1 Fire Protection Systems 2 Plumbing Design for Healthcare Facilities 3 Treatment of Industrial Waste 4 Irrigation Systems 5 Reflecting Pools and Fountains 6 Public Swimming Pools 7 Gasoline and Diesel Oil Systems 8 Steam and Condensate Piping 9 Compressed Air Systems 10 Solar Energy 11 Site Utility Systems Volume 4 Plumbing Components and Equipment (Revision date: 2012) Chapter 1 Plumbing Fixtures 2 Piping Systems 3 Valves 4 Pumps 5 Piping Insulation 6 Hangers and Supports 7 Vibration Isolation 8 Grease Interceptors 9 Cross-connection Control 10 Water Treatment 11 Thermal Expansion 12 Potable Water Coolers and Central Water Systems 13 Bioremediation Pretreatment Systems 14 Green Plumbing (The chapters and subjects listed for these volume are subject to modification, adjustment and change. The contents shown for each volume are proposed and may not represent the final contents of the volume. A final listing of included chapters for each volume will appear in the actual publication.)  Table of Contents 1 Sanitary Drainage Systems................................... 1 Codes and Standards....................................................... 1 Flow in Stacks............................................................ 1 Flow in Building Drains................................................. 2 Flow in Fixture Drains.................................................. 2 Pneumatic Pressures in a Sanitary Drainage System............................ 2 Fixture Discharge Characteristics............................................ 3 Drainage Loads........................................................ 3 Stack Capacities....................................................... 3 Capacities of Sloping Drains................................................. 5 Steady, Uniform Flow Conditions in Sloping Drains.......................... 6 Slope of Horizontal Drainage Piping....................................... 7 Loads for Drainage Piping............................................... 8 Components of Sanitary Drainage Systems.................................... 8 Sumps and Ejectors.................................................... 8 Cleanouts............................................................. 9 Floor Drains and Floor Sinks............................................ 10 Grates/Strainers...................................................... 11 Flashing Ring........................................................ 11 Sediment Bucket...................................................... 11 Accessories.......................................................... 12 Backwater Valves..................................................... 12 Oil Interceptors....................................................... 12 Fixture Wastewater Type............................................... 12 Supports............................................................ 12 Piping Materials......................................................... 12 Joining Methods......................................................... 13 Noise Transmission................................................... 13 Building Sewer Installation................................................ 14 Sanitation.............................................................. 15 Kitchen Areas........................................................... 15 Waterproofing........................................................... 15 Floor Leveling........................................................... 16 ii ASPE Plumbing Engineering Design Handbook — Volume 2 Thermal Expansion....................................................... 16 Protection from Damage................................................... 16 Alternate Sanitary Systems................................................ 16 Sovent and Provent...................................................... 17 Single-stack System...................................................... 18 Reduced-size Venting..................................................... 18 Vacuum Drainage System.................................................. 19 References.............................................................. 19 2 On-site Wastewater Reuse and Storm Water Harvesting......... 21 Terminology............................................................. 21 The Water Balance Equation............................................... 21 Codes and Standards...................................................... 22 Graywater Reuse......................................................... 22 System Components................................................... 22 Design Criteria for Graywater Supply and Consumption..................... 22 Design Estimates for Commercial Buildings............................... 23 Graywater Design Estimates for Residential Buildings....................... 24 Design Estimates for Graywater Irrigation Systems......................... 24 Graywater Treatment Systems.......................................... 25 Economic Analysis.................................................... 27 Precautions.......................................................... 27 Public Concerns and Acceptance......................................... 27 Storm Water Harvesting................................................... 28 References.............................................................. 29 3 Vents and Venting......................................... 31 Trap Design............................................................. 31 Types of Fixture Vents.................................................... 32 Common Vent........................................................ 32 Wet Venting......................................................... 32 Circuit Vent.......................................................... 32 Waste Stack.......................................................... 33 Combination Drain and Vent............................................ 33 Island Vent.......................................................... 34 Vent Systems............................................................ 34 Vent Stack Design........................................................ 35 Sizing a Vent Stack.................................................... 35 Offsets.............................................................. 37 Suds Pressure Zones................................................... 37 Main Vent........................................................... 37 Fixture Vent Design...................................................... 38 Alternative Vent Systems.................................................. 39 Air-admittance Valves.................................................. 39 Sovent Systems....................................................... 39 Single Stack.......................................................... 39 Table of Contents iii Jurisdictions............................................................ 39 Conclusion.............................................................. 40 4 Storm Drainage Systems.................................... 41 Code and Standards...................................................... 41 Materials............................................................... 42 Site Drainage and Infitration............................................... 42 The Rational Method.................................................. 43 Runoff Patterns....................................................... 43 Storm Water Quality.................................................. 43 Estimating Time of Concentration and Rainfall Intensity.................... 44 Collection Systems.................................................... 46 Conveyance......................................................... 46 Detention........................................................... 47 Infiltration........................................................... 48 Treatment........................................................... 48 Accessibility and Maintenance........................................... 48 Vector Control........................................................ 49 Interior Building Drainage System Design.................................... 49 General Design Criteria............................................... 49 Roof Drainage....................................................... 51 Rainfall Rates........................................................ 53 Interior Pipe Sizing and Layout Criteria.................................. 53 References.............................................................. 54 Appendix 4-A............................................................ 56 Runoff Volume Calculation for Typical Wisconsin Commercial Sites............ 56 Definitions........................................................... 56 Assumptions and Notes................................................ 56 5 Cold Water Systems........................................ 59 Codes and Standards...................................................... 59 Domestic Cold Water Meters............................................... 59 Meter Types......................................................... 59 Sizing the Water Meter................................................ 60 Cross-connection Controls................................................. 60 Design Guidelines for Cross-connection Controls........................... 60 Booster Pump Systems.................................................... 61 Pump Economy....................................................... 63 Booster Pump Features................................................ 63 Alternate Applications................................................. 64 Hydropneumatic Tank................................................. 64 Elevated Water Tank System............................................ 65 Expansion Tank...................................................... 67 Excess Water Pressure.................................................... 68 Pressure-regulating Valves............................................. 69 Water Hammer.......................................................... 70 iv ASPE Plumbing Engineering Design Handbook — Volume 2 Shock Intensity...................................................... 70 System Protection..................................................... 72 Sizing Water Piping....................................................... 73 Hazen-Williams Formula............................................... 73 Darcy-Weisbach Formula............................................... 74 Factors Affecting Domestic Water Pipe Sizing.............................. 75 Step-by-Step Guide to Sizing Water Pipe.................................. 84 Velocity Method...................................................... 89 Pressure Loss in Pipe Fittings and Valves................................. 89 Testing................................................................ 90 Cleaning and Disinfecting.................................................. 90 Glossary................................................................ 94 References.............................................................. 95 6 Domestic Water Heating Systems............................. 97 Domestic Water Heater Sizing.............................................. 98 Information Gathering................................................. 98 Water Heater Sizing Methods........................................... 98 Basic Formulae and Units................................................ 100 Heat Recovery—Electric Water Heaters..................................... 100 Hot Water Temperature.................................................. 101 Mixed Water Temperature................................................ 101 Water Heaters.......................................................... 101 Controls............................................................ 104 Stratification in Storage-type Heaters and Tanks.......................... 105 Hot Water Temperature ­Maintenance....................................... 105 Hot Water Circulation Systems......................................... 105 Self-regulating Heat Trace Systems..................................... 105 Relief Valves............................................................ 106 Sizing Pressure and Temperature Relief Valves............................ 106 Thermal Expansion...................................................... 106 Thermal Efficiency...................................................... 107 Legionnaires' Disease.................................................... 108 Varying Standards................................................... 109 Legionella Hot Spots.................................................. 109 Controlling Legionella................................................ 109 Legionella Control Recommendations................................... 111 Scalding............................................................... 111 Codes and Standards..................................................... 112 7 Fuel Gas Piping Systems................................... 113 Types of Gas Service..................................................... 113 Approvals.............................................................. 114 System Opperating Pressure.............................................. 115 Efficiency.............................................................. 115 Codes and Standards..................................................... 115 Table of Contents v Gas Meters............................................................. 115 Meter Types........................................................ 116 Meter Selection...................................................... 116 Pressure-regulating Valves................................................ 117 Gas Regulator Relief Vents............................................ 117 Control Valves.......................................................... 118 Excess Flow Valves................................................... 118 Appliance Control Valves.............................................. 118 Interlocks and Solenoid Valves......................................... 118 Appliances............................................................. 118 Venting................................................................ 118 Allowable Gas Pressure.................................................. 119 Laboratory Use......................................................... 121 Altitude Derating Factor.................................................. 121 Piping System Materials.................................................. 121 Metallic Pipe........................................................ 122 Metallic Tubing...................................................... 122 Plastic Pipe and Tubing............................................... 123 Fittings and Joints................................................... 124 Flexible Hose Connections............................................. 124 Grounding.......................................................... 125 Natural Gas Boosters.................................................... 125 Materials and Construction........................................... 125 Gas Laws for Boosters................................................ 126 High-rise Building Issues............................................. 126 Design Considerations................................................ 126 Sizing a Gas Booster................................................. 127 Pressure Droop and Peak Consumption.................................. 128 Interior Natural Gas Pipe Sizing........................................... 128 Data to Be Obtained.................................................. 128 Natural Gas Pipe Sizing Methods....................................... 130 Liquefied Petroleum Gas................................................. 131 Environmental Effects of Propane...................................... 131 Propane Storage Tanks............................................... 131 Propane Vaporization Requirements..................................... 134 Design Considerations................................................ 134 Liquefied Petroleum Gas Sizing......................................... 135 Glossary............................................................... 135 References............................................................. 136 8 Private On-site Wastewater Treatment Systems............... 139 Primary Treatment...................................................... 139 Soil Absorption Systems.................................................. 139 Estimating Soil Absorption Rates....................................... 140 Soil Absorption System Selection....................................... 142 In-ground Conventional Soil Absorption System........................... 142 vi ASPE Plumbing Engineering Design Handbook — Volume 2 Site Preparation and Construction...................................... 143 Collection and Treatment Alternatives...................................... 144 Alternatives to Gravity Collection and Distribution........................ 144 Alternatives to Conventional Primary and Secondary Treatment............. 145 Septic Tanks........................................................... 145 Functions of the Septic Tank........................................... 145 Septic Tank Materials................................................ 145 Septic Tank Construction, Installation, and Operation...................... 146 Cleaning Septic Tanks................................................ 148 Distribution Boxes................................................... 148 Sewage Disposal Systems for Institutions and Small Establishments............. 149 Water Conservation.................................................. 149 Special Fixtures..................................................... 149 Alternative Systems.................................................. 149 Special Design....................................................... 149 Individual Aerobic Wastewater Treatment Plants.......................... 150 Estimating Sewage Quantities............................................. 150 Inspection............................................................. 153 References............................................................. 154 9 Private Water Wells........................................ 155 Codes and Standards..................................................... 155 Sources of Supply....................................................... 155 Wells.................................................................. 155 Dug and Augered Wells............................................... 156 Bored Wells......................................................... 156 Driven Wells........................................................ 157 Jetted Wells........................................................ 157 Hydraulics of Wells...................................................... 157 Protection of Wells...................................................... 158 Water Demand.......................................................... 159 Water Quality.......................................................... 159 Filtration........................................................... 159 Softening.......................................................... 160 Scale and Corrosion Control........................................... 160 Taste and Odor Control............................................... 160 Prophylaxis........................................................ 160 Disinfection........................................................ 160 Radon Contamination................................................ 160 System Elements........................................................ 160 Pumps............................................................. 160 Submersible Well Pumps.............................................. 161 Storage Tanks...................................................... 162 Storage Tank Suction Piping.......................................... 163 Pressure Regulators................................................. 163 Performance Specifications................................................ 164 Table of Contents vii Corrosion Protection..................................................... 164 Initial Operation and Maintenance......................................... 164 Additional Information................................................... 164 10 Vacuum Systems.......................................... 165 Fundamentals.......................................................... 165 Pressure Measurement................................................... 165 Units of Measurement................................................ 165 Standard Reference Points and Conversions............................. 166 Flow Rate Measurement............................................. 166 General Vacuum Criteria................................................. 166 Adjusting the Vacuum Pump Rating for Altitude........................... 166 Time for a Pump to Reach the Rated Vacuum............................. 167 Adjusting Pressure Drop for Different Vacuum Pressures................... 168 Simplified Method of Calculating Velocity................................ 169 Vacuum Work Forces................................................. 169 Vacuum Pumps and Source Equipment...................................... 169 Vacuum Pumps...................................................... 169 Receivers........................................................... 170 Seal Liquids......................................................... 170 Vacuum Pressure Gauges.............................................. 171 Ancillary Equipment................................................. 171 Laboratory Vacuum Systems.............................................. 171 Codes and Standards................................................. 172 Vacuum Source...................................................... 173 Distribution Network................................................. 173 General System Layout............................................... 174 Pipe Sizing Criteria.................................................. 174 Piping Network Sizing............................................... 176 Vacuum Cleaning Systems................................................ 178 Types of Systems and Equipment....................................... 178 Codes and Standards................................................. 178 System Components.................................................. 178 Detailed System Design............................................... 180 Sizing the Piping Network............................................. 181 Piping System Friction Losses......................................... 183 Vacuum Producer Sizing.............................................. 184 Separator Selection and Sizing........................................ 186 References............................................................. 186 11 Water Treatment, Conditioning, and Purification............. 187 Codes and Standards..................................................... 187 Basic Water Chemistry................................................... 187 Water Impurities........................................................ 188 Turbidity.......................................................... 188 Microorganisms..................................................... 188 viii ASPE Plumbing Engineering Design Handbook — Volume 2 Other Organisms.................................................... 188 Dissolved Minerals and Organics....................................... 189 Alkalinity.......................................................... 189 Hardness.......................................................... 189 Iron............................................................... 189 Calcium............................................................ 190 Magnesium......................................................... 190 Silica.............................................................. 190 Sodium and Potassium............................................... 190 Chlorides and Sulfates................................................ 190 Nitrates........................................................... 190 Trace Elements..................................................... 190 Dissolved Gases..................................................... 190 Volatile Organic Compounds........................................... 190 Water Analysis and Impurity Measurement.................................. 191 pH................................................................ 191 Specific Resistance................................................... 192 Specific Conductance................................................. 193 Total Suspended Solids............................................... 193 Total Dissolved Solids................................................ 193 Total Organic Carbon................................................ 194 Silt Density Index................................................... 194 Deposits and Corrosion................................................... 194 Scale.............................................................. 195 Sludge............................................................. 195 Biological Fouling.................................................... 195 Corrosion.......................................................... 195 Prediction Scale Formations and Corrosion Tendencies......................... 196 Langelier Saturation Index............................................ 196 Ryzner Stability Index................................................ 196 Aggressiveness Index................................................. 196 Treatment Methodologies................................................. 197 Aeration........................................................... 197 Clarification........................................................ 198 Deaeration......................................................... 199 Dealkalizing........................................................ 199 Decarbonation...................................................... 199 Distillation......................................................... 199 Filtration.......................................................... 201 Ion Exchange and Removal............................................ 201 Service Deionization................................................. 208 Membrane Filtration and Separation.................................... 211 Microbial Control.................................................... 213 Chemicals.......................................................... 213 Water Treatment........................................................ 214 Table of Contents ix Utility Water Treatment.............................................. 214 Boiler Feed Water Conditioning........................................ 215 Cooling Water Conditioning........................................... 216 Potable Water Treatment............................................. 217 Water Purification....................................................... 217 Codes and Standards................................................. 218 Laboratory Systems.................................................. 218 Pharmaceutical Systems.............................................. 219 Feed Water......................................................... 219 Purification System Design............................................ 221 Pretreatment........................................................ 221 Central Purification Equipment........................................ 223 References............................................................. 224 12 Special Waste Drainage Systems............................ 227 Codes and Standards..................................................... 227 System Approval Requirements............................................ 227 Pipe Material and Joint Selection Considerations............................. 228 Pipe Sizing Considerations................................................ 228 pH Definiton........................................................... 228 General System Design Considerations...................................... 229 Acid Waste Drainage and Vent Systems...................................... 229 Health and Safety Concerns........................................... 229 Common Types of Acid............................................... 230 Selection of Laboratory Waste Piping and Joint Material................... 232 System Design Considerations......................................... 234 Acid Waste Treatment................................................ 235 Radioactive Waste Drainage and Vent Systems................................ 235 The Nature of Radiation.............................................. 236 Radiation Measurement.............................................. 237 Allowable Radiation Levels............................................ 237 Shielding........................................................... 238 Radioactive Materials................................................ 238 System Design Criteria............................................... 238 Infectious and Biological Waste Drainage Systems............................. 240 Codes and Standards................................................. 241 Biological Safety Levels............................................... 241 Effluent Decontamination System...................................... 241 System Components................................................. 242 System Design Considerations......................................... 242 Chemical Waste Systems.................................................. 242 Codes and Standards................................................. 242 Pipe Material and Joint Selection....................................... 242 System Design Considerations......................................... 243 Fire Suppression Water Drainage.......................................... 243 System Description.................................................. 243 x ASPE Plumbing Engineering Design Handbook — Volume 2 Flammable and Volatile Liquids............................................ 244 Oil in Water............................................................ 244 Methods of Separation and Treatment.................................. 245 References............................................................. 246 Index...................................................... 247 Table of Contents xi Figures Figure 1-1 Procedure for Sizing an Offset Stack............................... 5 Figure 1-2 Typical Ejector Pump Installation................................. 8 Figure 1-3 Typical Submerged Sump Pump Installation......................... 9 Figure 1-4 Basic Floor-Drain Components: (A) Removable Grate; (B) Rust-resistant Bolts; (C) Integral, One-piece Flashing Ring; (D) Cast Drain Body with Sump; (E) Sediment Bucket (op- tional).............................................................. 10 Figure 1-5 Types of Floor Drain: (A) Typical Drain with Integral Trap that May Be Cleaned Through Removable Strainer at Floor Level; (B) Floor Drain with Combination Cleanout and Backwater Valve, for Use Where Possibility of Backflow Exists; (C) Drain with Combined Clea- nout, Backwater Valve, and Sediment Bucket.............................. 11 Figure 1-6 Types of Backwater Valve....................................... 12 Figure 1-7 Inside Caulk Drain Body........................................ 13 Figure 1-8 Spigot Outlet Drain Body........................................ 13 Figure 1-9 No-hub Outlet Drain Body....................................... 14 Figure 1-10 IPS or Threaded Outlet Drain Body.............................. 14 Figure 1-11 Combination Floor Drain and Indirect Waste Receptor.............. 16 Figure 1-12 Typical Sovent Single-stack System.............................. 18 Figure 2-1 Wastewater Designations......................................... 23 Figure 2-2 The Constructed Environment Water Balance........................ 23 Figure 3-1 Sink Trap with Three Different Pressure Levels...................... 32 Figure 3-2 Common Vent for Two Sinks or Lavatories......................... 33 Figure 3-3 Circuit Vent Designs............................................ 33 Figure 3-4 Vent Blocked by a Wye Fitting.................................... 33 Figure 3-5 Two Vent Pipes Joined Above the Sink Rim......................... 34 Figure 3-6 Stack Vent Joined to a Drain Stack................................ 35 Figure 3-7 Vent Stack Joined to a Drain Stack................................ 35 Figure 3-8 Drain Stack Offsets............................................ 36 Figure 3-9 Relief Vents at a Drain Stack Offset............................... 37 Figure 3-10 Suds Pressure Zones.......................................... 38 Figure 4-1 Pre- and Post-construction Hydrographs............................ 43 Figure 4-2 Time of Concentration........................................... 44 Figure 4-3 Intensity-Duration-Frequency Curve............................... 45 Figure 4-4 Inlet Control Shown for a Pipe or Culvert........................... 46 Figure 4-5 Outlet Control Shown for a Pipe or Culvert.......................... 46 Figure 4-6 Crown Alignments on Storm Sewer Piping.......................... 48 xii ASPE Plumbing Engineering Design Handbook — Volume 2 Figure 4-7 Clear Water Waste Branches forConnection to Storm System.......... 50 Figure 4-8 Typical Roof Drain and Roof Leader............................... 51 Figure 4-9 Example of a Controlled-flow Drain............................... 53 Figure 5-1 RPZ Discharge Flow Rate....................................... 62 Figure 5-2 Simplified Downfeed Water Supply System with Simplified Elevated Water Tank.......................................................... 66 Figure 5-3 Piping Arrangement of an Elevated Water Tank..................... 67 Figure 5-4 Estimated Water House Tank Storage Capacity, Multiple Dwellings..... 67 Figure 5-5 Illustrations of a Shock Wave.................................... 71 Figure 5-6 (a, b) Plain Air Chambers, (c) Standpipe Air Chamber, (d) Rechargeable Air Chamber......................................................... 73 Figure 5-7(a) Bellows.................................................... 74 Figure 5-7(b) Piston..................................................... 74 Figure 5-8 Water Supply Graph............................................ 76 Figure 5-9 Kinematic Viscosity and Reynolds Number Chart.................... 77 Figure 5-10 Friction Factors for Any Kind and Size of Pipe..................... 78 Figure 5-11 Pipe Sizing Data, Smooth Pipe.................................. 79 Figure 5-12 Pipe Sizing Data, Fairly Smooth Pipe............................. 80 Figure 5-13 Pipe Sizing Data, Fairly Rough Pipe.............................. 81 Figure 5-14 Pipe Sizing Data, Rough Pipe................................... 82 Figure 5-15 Conversion of Fixture Units, fu, to gpm (L/s)....................... 85 Figure 5-16 Form to Track WFSU and Other Data............................ 86 Figure 5-17 Domestic Water Piping Sketch.................................. 87 Figure 5-18 Method for Conducting a Water Flow Test......................... 87 Figure 5-19(a) Disc-type Positive Displacement Magnetic Drive Meter............ 88 Figure 5-19(b) Compound Magnetic Drive Meter.............................. 88 Figure 5-19(c) Horizontal Turbine Meter.................................... 88 Figure 5-20 Establishing the Governing Fixture or Appliance................... 89 Figure 5-21 Determining Pressure Available for Friction....................... 90 Figure 5-22 Typical Resistance Coefficients for Valves and Fittings............... 92 Figure 5-22 (cont.) Typical Resistance Coefficients for Valves and Fittings......... 93 Figure 5-23 Flow Data, CV Values for Valves.................................. 95 Figure 6-1 Occupant Demographic Classifications............................. 99 Figure 7-1 Altitude Correction Factor...................................... 117 Figure 7-2 Variations of a Basic Simplex Booster System: (Standby Generator Application with Accumulator Tank Having a Limitation on Maximum Pressure.............. 119 Figure 7-2 (cont.) Variations of a Basic Simplex Booster System: (B) Dual Booster System for Critical Systems Like Those in Hospitals; (C) Heat Exchanger Loop­Example—Required for High Flow Range with Low Minimum Flow............................... 120 Figure 7-3 Gas Demand for Multiple-unit Dwellings with More than 50 Apartments123 Figure 7-4 Gas Demand for Multiple-unit Dwellings with Less than 50 Apartments 124 Figure 8-1 Three Legs of Disposal FieldFed from Cross Fitting Laid on Its Side... 142 Figure 8-2 Disposal Lines Connected by Headers to Circumvent Stoppages....... 142 Figure 8-3 Transverse and Lineal Sections of Drain FieldShowing Rock and Earth Backfill around Drain Tile.................................................... 143 Figure 8-4 Graph Showing RelationBetween Percolation Rate and AllowableRate at Sewage Ap- plication............................................................ 153 Table of Contents xiii Figure 9-1 Well Under (A) Static and (B) Pumping Conditions................. 158 Figure 9-2 Typical Pitless Adaptor........................................ 159 Figure 9-3 Typical Gravel Filter Well with a Vertical Turbine Pump(Note the concrete seal adja- cent to the outer well casing)........................................... 161 Figure 9-4 Graph Indicating Minimum Storage Tank Size..................... 163 Figure 9-5 Storage Tank Suction Piping Detail: (A) Sump Suction Alternate, (B) Anti-vortex Alternate........................................................... 163 Figure 10-1 Conversion of Vacuum Pressure Measurements................... 167 Figure 10-2 Schematic Detail of a Typical Laboratory Vacuum Pump Assembly.. 172 Figure 10-3 Typical Process Vacuum Pump Duplex Arrangement.............. 173 Figure 10-4 Direct Reading Chart Showing Diversity for Laboratory Vacuum..... 175 Figure 10-5 Acceptable Leakage in Vacuum Systems.......................... 177 Figure 10-6 Vacuum Cleaning Piping Friction Loss Chart..................... 182 Figure 10-7 Schematic of a Typical Wet Vacuum Cleaning Pump Assembly....... 185 Figure 11-1 Typical Water Analysis Report................................. 192 Figure 11-2 pH of Saturation for Water.................................... 197 Figure 11-3 Detail of Vapor Compression Still............................... 202 Figure 11-4 Detail of Multi-effect Still..................................... 204 Figure 11-5 Schematic Detail of Large-scale, Granular-activated Carbon Filter.... 205 Figure 11-6 Typical Single-bed Ion Exchanger............................... 206 Figure 11-7 Typical Dual-bed Ion Exchanger................................ 207 Figure 11-8 Typical Mixed-bed Ion Exchanger............................... 208 Figure 11-9 Schematic Operation of a Continuous Deionization Unit............ 209 Figure 11-10 Hollow-fiber Reverse Osmosis Configuration..................... 212 Figure 11-11 Spiral-wound Reverse Osmosis Configuration.................... 212 Figure 11-12 Tubular Reverse Osmosis Configuration........................ 212 Figure 11-13 Plate-and-Frame Reverse Osmosis Configuration................. 212 Figure 11-14 UV Wavelength Spectrum.................................... 214 Figure 11-15 Principle of Corona Discharge Ozone Generator.................. 215 Figure 11-16 Typical Pharmaceutical Water Flow Diagram.................... 222 Figure 12-1 Typical Acid-resistant Manhole................................. 233 Figure 12-2 Typical Large Acid-neutralizing Basin........................... 234 Figure 12-3 Typical Continuous Acid Waste Treatment System................. 236 Figure 12-4 Typical Oil Interceptor........................................ 244 Figure 12-5 Typical Gravity Drawoff Installation: (A) Plan and (B) Isometric..... 245 xiv ASPE Plumbing Engineering Design Handbook — Volume 2 Table of Contents xv Tables Table 1-1 Residential Drainage Fixture Unit (dfu) Loads........................ 3 Table 1-2 Capacities of Stacks.............................................. 4 Table 1-3 Maximum Permissible Fixture Unit Loads for Sanitary Stacks........... 4 Table 1-4 Values of R, R2/3, AF , and AH........................................ 6 Table 1-5 Approximate Discharge Rates and Velocities in Sloping Drains, n = 0.015.. 7 Table 1-6 Slopes of Cast Iron Soil Pipe Sanitary Sewer Required to Obtain Self-cleansing Veloci- ties of 2.0 and 2.5 ft/sec. (based on Manning formula with n = 0.012)............ 7 Table 1-7 Building Drains and Sewers....................................... 7 Table 1-8 Recommended Grate Open Areas for Various Floor Drains with Outlet Pipe Sizes........................................................... 10 Table 1-9 Relative Properties of Selected Plumbing Materials for Drainage Systems. 14 Table 2-1 Water Reuse Issues of Concerns.................................... 24 Table 2-2 LEED 2009 Baseline for Plumbing Fixtures........................... 25 Table 2-3 Design Criteria for Graywater Irrigation of Six Typical Soils............. 25 Table 2-4 Minimum Horizontal Distances for Graywater System Elements......... 26 Table 2-5 Graywater Treatment Processes for Normal Process Efficiency......... 26 Table 2-6 Comparison of Graywater System Applications....................... 26 Table 2-7 Contaminant Concentration in Urban Storm Water.................... 27 Table 2-8 Water Balance Worksheet......................................... 28 Table 3-1 Maximum Distance of a Fixture Trap from a Vent Connection........... 34 Table 3-2 IPC Sizes of Individual Vents and Vent Branches...................... 39 Table 3-3 UPC Sizes of Any Vent........................................... 40 Table 4-1 Coefficients for Use with the Rational Method........................ 42 Table 4-2 Contaminant Concentrations in Urban Storm Water................... 44 Table 4-3 Sources of Pollutants in Wisconsin Storm Water....................... 45 Table 4-4 Windows TR-55 Capabilities and Limitations......................... 46 Table 4-5 Design Infiltration Rates for Soil Textures Receiving Storm Water........ 48 Table 4-6 Sizes of Roof Drains and Vertical Pipes............................. 51 Table 4-7 Size of Horizontal Storm Drains................................... 54 Appendix A Table 1 Rainfall (inches) for Selected Municipalities................. 57 Table 5-1 Displacement-type Meters Meeting AWWA Specifications—Flow Pressure Loss Averages............................................................ 61 Table 5-2 Compound-type Meters Meeting AWWA Specifications—Flow Pressure Loss Averages............................................................ 61 Table 5-3 Turbine-type Meters Meeting AWWA Specifications—Flow Pressure Loss Averages............................................................ 61 xvi ASPE Plumbing Engineering Design Handbook — Volume 2 Table 5-4 BFP Flow Rate................................................. 62 Table 5-5 Pressure Losses Through RPZs................................... 63 Table 5-6 Hydropneumatic Tank Volume Ratios.............................. 64 Table 5-6(SI) Hydropneumatic Tank Volume Ratios........................... 64 Table 5-7 Tank Size Varying by Its Location in a Building...................... 66 Table 5-8 Size of Gravity Tanks............................................ 68 Table 5-9 Standard Wood House Tanks..................................... 68 Table 5-10 Water Expansion Above 40°F.................................... 69 Table 5-11 Expansion Tank Pressure Ratios................................. 69 Table 5-12 Required Air Chambers......................................... 73 Table 5-13 Water Hammer Arrester Sizing................................... 74 Table 5-14 Densities of Pure Waterat Various Temperatures.................... 74 Table 5-15 Surface Roughness Coefficient (C) Values for Various Types of Pipe..... 75 Table 5-16 Values of ε (Absolute Roughness)................................. 78 Table 5-17 Average Values for Coefficient of Friction, f......................... 78 Table 5-18 Load Values Assigned to Fixtures................................. 83 Table 5-19 Estimating Demand............................................ 83 Table 5-20 Minimum Sizes of Fixture Water Supply Pipes...................... 86 Table 5-21 Water Distribution System Design Criteria Required Capacity at Fixture Supply Pipe Outlets.............................................................. 86 Table 5‑22 Allowance for Friction Loss in Valves and Threaded Fittings........... 91 Table 6-1 Hot Water Demand per Fixture for Various Types of Buildings......... 99 Table 6-2 Low, Medium, and High Guidelines: Hot Water Demand and Use for Multifamily Build- ings............................................................... 100 Table 6-3 Typical Hot Water Temperatures for Plumbing Fixtures and Equipment. 101 Table 6-4 Hot Water Multiplier, P......................................... 102 Table 6-4 Hot Water Multiplier, P (continued)............................... 103 Table 6-4 Hot Water Multiplier, P (continued)............................... 104 Table 6-5 Thermal Properties of Water..................................... 107 Table 6-6 Recommended Water System Temperatures........................ 108 Table 6-7 Time/Water Temperature ­Combinations Producing Skin Damage....... 111 Table 7-1 Average Physical Properties of Natural Gas and Propane............. 113 Table 7-2 Physical and Combustion Properties of Commonly Available Fuel Gases. 114 Table 7‑3 Approximate Gas Demand for Common Appliances.................. 116 Table 7-4 Equivalent Lengths for Various Valve and Fitting Sizes............... 123 Table 7-5 Pipe Sizing for Pressure Less than 2 psi (14 kPa) and Loss of 0.3 inch (7.5 mm) of Wa- ter Column......................................................... 126 Table 7-6 Specific Gravity Multipliers...................................... 126 Table 7-7 Conversion of Gas Pressure to Various Designations................. 127 Table 8-1 Maximum Soil Application Rates Based on Morphological Soil Evaluation (in gals./ sq.ft./day)........................................................... 140 Table 8-2 Maximum Soil Application Rates Based onPercolation Rates........... 140 Table 8-3 Recommended Setbacks for Soil Absorption Systems................. 142 Table 8-4 Liquid Capacity of Tank........................................ 146 Table 8-5 Allowable Sludge Accumulation.................................. 147 Table 8-6 Average Wastewater Flowsfrom Residential Sources................. 150 Table of Contents xvii Table 8-7 Typical Wastewater Flows from Commercial Sources................. 150 Table 8-8 Typical Wastewater Flows from Institutional Sources................ 151 Table 8-9 Typical Wastewater Flows from Recreational Sources................ 151 Table 8-10 Quantities of Sewage Flows..................................... 152 Table 8-11 Estimated Distribution of Sewage Flows.......................... 153 Table 8-12 Allowable Rate of Sewage Application to a Soil Absorption System..... 153 Table 10-1 Conversions fromTorr to Various Vacuum Pressure Units............ 166 Table 10-2 Expanded Air Ratio, 29.92/P,as a Function of Pressure, P (in. Hg)..... 168 Table 10-3 Direct Ratio for Converting scfm to acfm (sL/s to aL/s).............. 168 Table 10-4 Barometric Pressure Corresponding to Altitude.................... 168 Table 10-5 Factor for Flow Rate Reduction Due to Altitude.................... 168 Table 10-6 Constant, C, for Finding Mean Air Velocity........................ 169 Table 10-7 IP and SI Pressure Conversion.................................. 170 Table 10-8 Diversity Factor for LaboratoryVacuum Air Systems................ 174 Table 10-9 Pressure Loss Data for Sizing Vacuum Pipe, Low Pressure Vacuum System............................................................. 175 Table 10-9(A) Pressure Loss Data for Sizing vacuum Pipe, High Vacuum Pressure System............................................................. 176 Table 10-10 Vacuum Pump Exhaust Pipe Sizing............................. 176 Table 10-11 Recommended Sizes of Hand Tools and Hose..................... 180 Table 10-12 Flow Rate and Friction Loss for Vacuum Cleaning Tools and Hoses... 181 Table 10-13 Recommended Velocities for Vacuum Cleaning Systems............. 181 Table 10-14 Pipe Size Based on Simultaneous Usage......................... 183 Table 10-15 Equivalent Length (ft) ofVacuum Cleaning Pipe Fittings............ 183 Table 10-16 Classification of Material for Separator Selection.................. 184 Table 11-1 Important Elements, Acid Radicals, andAcids in Water Chemistry..... 189 Table 11-2 Converting ppm of Impurities to ppm of Calcium Carbonate.......... 192 Table 11-3 Resistivity and Conductivity Conversion.......................... 193 Table 11-4 Prediction of Water Tendencies by the Langelier Index.............. 196 Table 11-5 Numerical Values for Substitution in Equation 11-3 to Find the pHs of Saturation for Water.............................................................. 197 Table 11-6 Prediction of Water Tendenciesby the Ryzner Index................. 198 Table 11-7 Typical Cations and Anions Found in Water....................... 205 Table 11-8 Comparison of Reverse Osmosis Polymers......................... 213 Table 11-9 Recommended Boiler Feed Water Limits and Steam Purity........... 216 Table 11-10 Water Treatment Technology for Small Potable Water Systems...... 218 Table 11-11 CAP and ASTM Reagent‑grade Water Specifications............... 219 Table 11-12 NCCLS Reagent-grade Water Specifications...................... 220 Table 11-13 AAMI/ANSI Water Quality Standards........................... 220 Table 11-14 ASTM Electronics‑grade Water Standard........................ 220 Table 11-15 USP XXII Purified Water andWFI Water Purity Standards.......... 221 Table 12-1 Drainage Pipe Sizing.......................................... 230 Table 12-1(M) Drainage Pipe Sizing....................................... 231  100% recycled. Over the decades, we’ve recycled millions of tons of scrap iron into quality cast iron pipe and fittings. So while green construction might be relatively new, it’s nothing new to us. charlottepipe.com  1 Sanitary Drainage Systems The purpose of the sanitary drainage system is to remove effluent discharged from plumbing fixtures and other equipment to an approved point of disposal. FLOW IN STACKS A stack is the main vertical pipe that carries away discharge from water closets and urinals (soil stack) A sanitary drainage system generally consists of or other clear water waste from equipment and non- horizontal branches, vertical stacks, a building drain sanitary fixtures (waste stack). Flow in the drain inside the building, and a building sewer from the empties into the vertical stack fitting, which may be building wall to the point of disposal. a long-turn tee-wye or a short-turn or sanitary tee. To economically design a sanitary drainage Each of these fittings permits flow from the drain to system, the designer should use the smallest pipes enter the stack with a component directed vertically possible according to the applicable code that can downward. Depending on the rate of flow out of the rapidly carry away the soiled water from individual drain into the stack, the diameter of the stack, the fixtures without clogging the pipes, leaving solids in type of stack fitting, and the flow down the stack the piping, generating excessive pneumatic pressures from higher levels (if any), the discharge from the at points where the fixture drains connect to the fixture drain may or may not fill the cross-section of stack (which might cause the reduction of trap water the stack at the level of entry. In any event, as soon seals and force sewer gases back through inhabitable as the water enters the stack, the force of gravity areas), and creating undue noise. rapidly accelerates it downward, and before it falls Since vents and venting systems are described in very far, it assumes the form of a sheet around the Chapter 3 of this volume, the following discussion cen- wall of the stack, leaving the center of the pipe open ters only on the design of drain and waste systems. for the flow of air. This sheet of water continues to accelerate until CODES AND STANDARDS the frictional force exerted by the wall of the stack on Plumbing codes establish a minimum acceptable the falling sheet of water equals the force of gravity. standard for the design and installation of systems, From that point on, if the distance the water falls is including sanitary drainage. There are various sufficient enough and provided that no flow enters the model codes, but some states and large cities have stack at lower levels to interfere with the sheet, the adopted their own plumbing codes, rather than the sheet remains unchanged in thickness and velocity ones usually associated with the region. Because of until it reaches the bottom of the stack. The ultimate this non-standardization, the actual plumbing code vertical velocity the sheet attains is called the “ter- used for each specific project must be obtained from minal velocity.” The distance the sheet must fall to a responsible code official. attain this terminal velocity is called the “terminal A variety of different codes are used to lay out length.” and size interior sanitary drainage systems, and the Following are the formulae developed for calculat- information pertaining to sanitary design for a spe- ing the terminal velocity and terminal length: cific project appears in the approved local plumbing Equation 1-1a (terminal velocity) code, which must be the primary method used for the accepted methods and sizing. The tables and charts V T = 3.0(Q/d)2/5 appearing in this chapter are used only to illustrate Equation 1-1b (terminal length) and augment discussions of sizing methods, sizing LT = 0.052V T2 procedures, and design methods and should not be used for actual design purposes. where 2 ASPE Plumbing Engineering Design Handbook — Volume 2 VT = Terminal velocity in the stack, feet per second Less hydraulic jump occurs if the horizontal drain is (fps) (meters per second) larger than the stack. After the hydraulic jump occurs LT = Terminal length below the point of flow entry, and water fills the drain, the pipe tends to flow full feet (meters) until the friction resistance of the pipe retards the Q = Quantity rate of flow, gallons per minute (gpm) flow to that of uniform flow conditions. (liters per second) d = Diameter of stack, inches (millimeters) Flow in Fixture Drains Terminal velocity is approximately 10 to 15 fps Determination of the required drain size is a rela- (3.05 to 4.57 meters per second), and this velocity is tively simple matter, since the fixture drain must be attained within 10 to 15 feet (3.05 to 4.57 meters) of adequate only to carry the discharge from the fixture fall from the point of entry. to which it is attached. Because of the problem of self- At the center of the stack is a core of air that is siphonage, however, it is advisable to select a diameter dragged along with the water by friction. A supply large enough that the drain flows little more than source of air must be provided to avoid excessive pres- half-full under the maximum discharge conditions sures in the stack. The usual means of supplying this air likely to be imposed by the fixture. are through the stack vent or vent stack. The entrained For example, a lavatory drain capable of carrying air in the stack causes a pressure reduction inside the the flow discharged from a lavatory may still flow full stack, which is caused by the frictional effect of the fall- over part or all of its length. This occurs for several ing sheet of water dragging the core of air with it. reasons. The vertical component of the flow out of the If the sheet of water falling down the stack passes trap into the drain tends to make the water attach to a stack fitting through which the discharge from a fix- the upper elements of the drain, and a slug of water is ture is entering the stack, the water from the branch formed, filling the drain at that point. If insufficient mixes with or deflects the rapidly moving sheet of air is aspirated through the overflow, the pipe will water. An excess pressure in the drain from which flow full for part of its length, with the average flow the water is entering the stack is required to deflect velocity being less than the normal velocity for the the sheet of water flowing downward or to mix the flow rate in the drain at a given slope. branch water with it. The result is a back-pressure In the past, with a fixture such as a toilet, the surge created in the branch, which increases with the flow of water from the toilet continued almost without rate and flow velocity down the stack and with the change even along a very long drain until it reached the flow rate out of the drain. stack. This still is generally true, but the use of low-flow The importance of this knowledge is that it con- and dual-flush toilets requires the design of the hori- clusively abolishes the myth that water falling from zontal piping to be reconsidered. It cannot be assumed, a great height will destroy the fittings at the base of for all practical purposes, that the surge caused by the a stack. The velocity at the base of a 100-story stack discharge of a toilet through a fixture drain reaches the is only slightly and insignificantly greater than the stack or horizontal branch with practically the same velocity at the base of a three-story stack. The concern velocity it had when it left the fixture. is the weight of the stack, which must be supported PNEUMATIC PRESSURES IN A by clamps at each floor level. ­SANITARY DRAINAGE SYSTEM Flow in Building Drains Due to the pressure conditions in a stack and a build- When the sheet of water reaches the bend at the base ing drain, wastewater does not fill the cross-section of the stack, it turns at approximately right angles anywhere, so the air can flow freely with the water. into the building drain. Flow enters the horizontal The water flowing down the wall of the stack drags drain at a relatively high velocity compared to the air with it by friction and carries the air through the flow velocity in a horizontal drain under uniform building drain to the street sewer. The air is then flow conditions. The slope of the building drain is vented through the main street sewer system so not adequate to maintain the velocity that existed dangerous pressures do not build up. The generally in the vertical sheet when it reached the base of accepted pressure is ±1 inch of water column. the stack and must flow horizontally. The velocity When air enters the top of the stack to replace the of the water flowing along the building drain and air being carried with the water, the pressure inside sewer decreases slowly and then increases suddenly the stack decreases. However, because of the head loss as the depth of flow increases and completely fills necessary to accelerate the air and to provide for the the cross-section of the drain. This phenomenon is energy loss at the entrance, this pressure reduction called a “hydraulic jump.” is negligible, amounting to only a small fraction of The critical distance at which the hydraulic jump an inch of water. Appreciable pressure reductions may occur varies from immediately at the stack fitting are caused by the partial or complete blocking of the to 10 times the diameter of the stack downstream. Chapter 1 — Sanitary Drainage Systems 3 stack by water flowing into the stack from a hori- Table 1-1 Residential Drainage Fixture Unit (dfu) Loads zontal branch. Fixture IPC UPC A small increase in pneumatic pressure will oc- Bathtub 2 3 cur in the building drain even if the airflow is not Clothes washer 3 3 completely blocked by a hydraulic jump or by sub- Dishwasher 2 2 mergence of the outlet and the building sewer. This is Floor drain 3 – due to the decrease in cross-sectional area available 1¼-inch trap loading – 1 for airflow when the water flowing in the drain has 1½-inch trap loading – 3 adapted to the slope and diameter of the drain. 2-inch trap loading – 4 3-inch trap loading – 6 FIXTURE DISCHARGE 4-inch trap loading – 8 ­CHARACTERISTICS Laundry tray 2 2 The discharge characteristic curves—flow rates as Lavatory, single 1 1 a function of time—for most toilet bowls have the Lavatory, in sets of two or three 2 2 same general shape, but some show a much lower Shower (each head) 2 2 peak and a longer period of discharge. The discharge Kitchen sink (including dishwasher and garbage 3 3 characteristics for various types of bowls, particu- disposal) larly for low-flow toilets, have a significant impact Toilet (1.6-gpf gravity tank) 4 4 on estimating the capacity of a sanitary drainage Toilet (1.6-gpf flushometer tank) 5 5 system. Other plumbing fixtures, such as sinks, lava- Toilet (1.6-gpf flushometer valve) 4 4 tories, and bathtubs, may produce similar surging flows in drainage systems, but they do not have the or recently conducted studies of drainage loads on same effect as water closets. drainage systems may change these values. These include studies of reduced flow from water-saving Drainage Loads fixtures, models of stack, branch, and house drain Single-family dwellings contain certain plumbing flows, and actual fixture use. fixtures, such as one or more bathroom groups, each consisting of a toilet, lavatory, and bathtub or Stack Capacities shower stall, a kitchen sink, dishwasher, and washing The criterion of flow capacities in drainage stacks is machine. Large buildings also have other fixtures, based on the limitation of the water-occupied cross- such as slop sinks and drinking water coolers. The section to a specified fraction (rs) of the cross-section important characteristic of these fixtures is that they of the stack where terminal velocity exists, as sug- are not used continuously. Rather, they are used with gested by earlier investigations. irregular frequencies that vary greatly during the day. Flow capacity can be expressed in terms of the In addition, the various fixtures have quite different stack diameter and the water cross-section. discharge characteristics regarding both the average Equation 1-2 flow rate per use and the duration of a single discharge. Q = 27.8 x rs5/3 x D8/3 Consequently, the probability of all the fixtures in the building operating simultaneously is small. where Assigning drainage fixture unit (dfu) values to Q = Capacity, gpm (liters per second) fixtures to represent their load-producing effect on the rs = Ratio of the cross-sectional area of the sheet plumbing system originally was proposed in 1923 by Dr. of water to the cross-sectional area of the Roy B. Hunter. The fixture unit values were designed stack D = Diameter of the stack, inches (millimeters) for application in conjunction with the probability of simultaneous use of fixtures to establish the maximum Values of flow rates based on r = ¼, 7/24, and are permissible drainage loads expressed in fixture units tabulated in Table 1-2. rather than in gpm of drainage flow. Table 1-1 gives Whether or not Equation 1-2 can be used safely to the recommended fixture unit values. The plumbing predict stack capacities remains to be confirmed and engineer must conform to local code requirements. accepted. However, it provides a definite law of varia- Dr. Hunter conceived the idea of assigning a fix- tion of stack capacity with diameter. If this law can be ture unit value to represent the degree to which a shown to hold for the lower part of the range of stack fixture loads a system when used at its maximum as- diameters, it should be valid for the larger diameters. sumed flow and frequency. The purpose of the fixture It should be remembered that both F.M. Dawson and unit concept is to make it possible to calculate the Dr. Hunter, in entirely independent investigations, design load of the system directly when the system came to the conclusion that slugs of water, with their is a combination of different kinds of fixtures, with accompanying violent pressure fluctuations, did not each having a unique loading characteristic. Current occur until the stack flowed one-quarter to one-third 4 ASPE Plumbing Engineering Design Handbook — Volume 2 Table 1-2 Capacities of Stacks was solved in a study of stack capacities made by Wyly Pipe Size, Flow, gpm (L/s) and Eaton at the National Bureau of Standards for in. (mm) r = 1⁄4 r = 7⁄24 r = 1⁄3 the Housing and Home Finance Agency in 1950. 2 (50) 17.5 (1.1) 23.0 (1.45) 28 (1.77) The water flowing out of the branch can enter the 3 (80) 52 (3.28) 70 (4.41) 85 (5.36) 4 (100) 112 (7.07) 145 (9.14) 180 (11.35) stack only by mixing with the stream flowing down 5 (125) 205 (12.93) 261 (16.5) 324 (20.44) the stack or by deflecting it. Such a deflection of the 6 (150) 330 (20.82) 424 (26.8) 530 (33.43) high-velocity stream coming down the stack can be 8 (200) 710 (44.8) 913 (57.6) 1,140 (72) accomplished only if there is a significant hydrostatic 10 (250) 1,300 (82.0) 1,655 (104.4) 2,068 (130.5) 12 (300) 2,082 (131.4) 2,692 (170) 3,365 (212.3) pressure in the branch, since a force of some kind is required to deflect the downward flowing stream and change its momentum. This hydrostatic pressure is Table 1-3 Maximum Permissible Fixture Unit Loads for Sanitary Stacks created by the water backing up in the branch until Maximum dfu that May Be Connected the head changes the momentum of the stream al- One stack Stacks with more than ready in the stack to allow the flow from the branch Any of three three branch intervals to enter the stack. Diameter horizontal or fewer Total at The maximum hydrostatic pressure that should be of Pipe, in. fixture branch Total for one branch permitted in the branch as a result of the backing up (mm) brancha intervals stack interval 1½ (40) 3 4 8 2 of the spent water is based on this consideration: The 2 (50) 6 10 24 6 backup should not be of a magnitude that would cause 2½ (65) 12 20 42 9 the water to back up into a shower stall or cause slug- b b b 3 (80) 20 48 72 20b 4 (100) 160 240 500 90 gish flow. It is half of the diameter of the horizontal 5 (125) 360 540 1,100 200 branch at its connection to the stack. That is, it is the 6 (150) 620 960 1,900 350 head measured at the axis of the pipe that will cause 8 (200) 1,400 2,200 3,600 600 the branch to flow full near the exit. 10 (250) 2,500 3,800 5,600 1,000 12 (300) 3,900 6,000 8,400 1,500 When a long-turn tee-wye is used to connect the 15 (380) 7,000 – – – branch to the stack, the water has a greater vertical a Does not include branches of the building drain. velocity when it enters the stack than it does when b No more than two water closets or bathroom groups within eachbranch interval or more than six water closets or bathroom groups on the stack. a sanitary tee is used. The back-pressures should be smaller in this case for the same flows down the stack and in the branch. full. Most model codes have based their stack loading Table 1-3 shows the maximum permissible fixture tables on a value of r = ¼ or 7/24. unit loads for sanitary stacks. The procedure for siz- The recommended maximum permissible flow in ing a multistory stack (greater than three floors) is a stack is 7/24 of the total cross-sectional area of the to first size the horizontal branches connected to the stack. By substituting r = 7/24 into Equation 1-2, stack. This is done by totaling the fixture units con- the corresponding maximum permissible flow for the nected to each branch and using the corresponding various sizes of pipe in gpm can be determined. Table figure in column 2 of Table 1-3. Next, total all the 1‑3 lists the maximum permissible fixture units (fu) fixture units connected to the stack and determine to be conveyed by stacks of various sizes. The table the size from the same table, under column 4. Imme- was created by taking into account the probability diately check the next column, “Total at One Branch of simultaneous use of fixtures. For example, if 500 Interval,” and determine if this maximum is exceeded fixture units is the maximum loading for a 4-inch by any of the branches. If it is exceeded, the stack (100-millimeter) stack, then 147 gpm (9.3 liters per as originally determined must be increased at least second) is equivalent to 500 fixture units. This is the one size, or the loading of the branches must be rede- total load from all branches. signed so the maximum conditions are satisfied. It should be noted that there is a restriction on For example, consider a 4-inch (100-millimeter) the amount of flow permitted to enter a stack from stack more than three stories high. The maximum any branch when the stack is more than three branch loading for a 4-inch (100-millimeter) branch is 160 intervals. If an attempt is made to introduce an overly fixture units, as shown in column 2 of Table 1-3. This large flow into the stack at any one level, the inflow load is limited by column 5 of the same table, which will fill the stack at that level and will back up the permits only 90 fixture units to be introduced into water above the elevation of inflow, which will cause a 4-inch (100-millimeter) stack in any one-branch violent pressure fluctuations in the stack—resulting interval. The stack would have to be increased in in the siphoning of trap seals—and also may cause size to accommodate any branch load exceeding 90 sluggish flow in the horizontal branch. This problem fixture units. Chapter 1 — Sanitary Drainage Systems 5 To illustrate the require- ments of a stack with an offset of more than 45 degrees from the vertical, Figure 1-1 shows the sizing of a stack in a 12-story building, with one offset between the fifth and sixth floors and another offset below the street floor. Sizing is computed as fol- lows: 1. Compute the fixture units connected to the stack. In this case, assume 1,200 fixture units are connected to the stack from the street floor through the top floor. 2. Size the portion of the stack above the fifth- floor offset. There are 400 fixture units from the top floor down through the sixth floor. According to Table 1-3, column 4, 400 fixture units require a 4-inch (100- millimeter) stack. 3. Size the offset on the fifth floor. An offset is sized and sloped like a building drain. 4. Size the lower por- tion of the stack fr