Domestic Water Piping Design Guide - Engineering Pro Guides
Domestic Cold Water SystemsTable of Contents1.0 Introduction . 41.1 Units . 42.0 Disclaimer . 43.0Plumbing Codes . 53.1Applicable Systems . 53.2Water Supply Fixture Units . 54.0Domestic Water Pipe Sizing . 74.1Main and Branch Piping Sizing . 84.1.1Step 1: Determine WSFU . 84.1.2Step 2: Convert WSFU to GPM . 94.1.3Step 3: Quick Sizing Table . 104.2Fixture Piping Sizing . 134.3Sample Pipe Sizing Discussion . 144.4Sample Pipe Sizing results . 165.0Domestic Water Pressure Calculator . 175.1Fluid Velocity . 215.2Reynolds Number . 215.3Friction Factor . 215.4Pressure Drop – Piping & Valves/Fittings . 225.5Pressure Drop – Equipment . 235.6Joining Method . 235.6.1Soldering . 235.6.2Brazing . 245.6.3Press Connection (Propress) . 246.0Pipe Materials . 256.1ABS Piping . 256.1.1ASTM D 1527 Schedule 40 & Schedule 80 . 266.1.2ASTM D 2282 Standard Dimension Ratio (SDR) . 276.1.3Pressure Ratings . 296.2Brass Piping . 306.2.1Regular Strength . 306.2.2Extra Strength . 30Domestic Water Systems-1http://www.engproguides.com
6.2.36.3Pressure Ratings . 31CPVC Piping . 336.3.1ASTM F441 Standard Specification for Chlorinated Poly Vinyl Chloride (CPVC)Plastic Pipe, Schedules 40 and 80 . 336.3.2ASTM F442 Standard Specification for Chlorinated Poly Vinyl Chloride (CPVC)Plastic Pipe, SDR-PR . 356.4Copper Piping and Tubing . 366.4.1Difference Between Piping and Tubing . 366.4.2Copper Types . 366.4.3Type K Copper Tubing . 366.4.4Type L Copper Tubing . 376.4.5Type M Copper Tubing . 386.4.6Type DWV Copper Tubing . 386.4.7Type Medical Gas Copper Tubing . 386.4.8Pressure Ratings of Copper Tubing . 396.5PEX Plastic Pipe and Tubing . 426.5.1Pressure Ratings . 436.6Ductile Iron Water Pipe . 446.7Galvanized Steel Piping . 456.7.16.8Pressure Ratings . 46Polyethylene and Polypropylene Plastic Piping and Tubing . 476.8.1Pipe Dimensions . 476.8.2Pressure Ratings . 496.9Polyvinyl Chloride (PVC) Piping . 506.9.1Pipe Dimensions . 506.9.2Pressure Ratings . 536.10Stainless Steel Piping . 546.10.1Pipe Dimensions . 546.10.2Pressure Ratings . 577.0Valves . 587.1Types of Valves . 587.2Valve Flow Characteristics . 617.3Valve Sizing Method . 628.08.1Miscellaneous Design Issues . 63Hydraulic Shock or Water Hammer . 63Domestic Water Systems-2http://www.engproguides.com
8.2Sterilization of Domestic Water Piping . 638.3Water Leak Testing . 63Domestic Water Systems-3http://www.engproguides.com
1.0 INTRODUCTIONA domestic water system describes the indoor and outdoor potable water distribution system. Itincludes the connection to the water supply, whether it is an underground central city, county, stateor federal distribution system or a private well. The domestic water system includes abovegroundand belowground piping, valves, fittings, ancillary equipment and the various plumbing fixtures thatuse the potable water.Figure 1: This figure shows an example of a domestic water distribution system (only cold water) for acommercial kitchen. This figure will be used to exemplify how a domestic water system is sized.1.1 UNITSThe primary units that are used in this calculator and guide are the United States CustomarySystem Units (USCS). However, there will be another version provided in International System ofUnits (SI). This version is not guaranteed and is not included with the purchase of this product.2.0 DISCLAIMERDomestic Water Systems-4http://www.engproguides.com
In no event will Engineering Pro Guides be liable for any incidental, indirect, consequential,punitive or special damages of any kind, or any other damages whatsoever, including, withoutlimitation, those resulting from loss of profit, loss of contracts, loss of reputation, goodwill, data,information, income, anticipated savings or business relationships, whether or not Engineering ProGuides has been advised of the possibility of such damage, arising out of or in connection with theuse of this document/software or any referenced documents and/or websites.This design guide book and calculator was created for the design of primarily commercial andresidential domestic water systems. Although these products can be used for industrial typesystems, the intricacies of industrial type plumbing fixtures make it very difficult and it is notrecommended that you use this calculator industrial purposes.3.0 PLUMBING CODESThe design of a plumbing system is greatly influenced by your applicable codes. The mostcommon plumbing codes are the (1) International Plumbing Code or IPC, (2) Uniform PlumbingCode or UPC and (3) Unified Facilities Criteria Plumbing Systems or UFC 3-420-01 PlumbingSystems. Each plumbing design will follow under a certain jurisdiction, which is the governingpower that makes the legal determinations and interpretations of the code. For example, a jobmay be on a federal base, which means the federal government has jurisdiction. This jurisdictionthen determines that all plumbing designs must follow UFC 3-420-01 Plumbing Systems. If you doa job for a state government property, then that state has jurisdiction and you need to check withthe jurisdiction for the applicable code. There are many different jurisdictions like federal, state,city and county. Each of these jurisdictions will tell you which code to follow, whether it is IPC,UPC or UFC and each of the jurisdictions may have adapted the code to fit their specific location’sneeds.This design guide will focus on the most applicable codes, the IPC. Just be sure to search throughyour jurisdiction for any adaptations.3.1APPLICABLE SYSTEMSPlumbing systems include domestic water (cold and hot), sanitary sewer and vent, storm drain,special waste like grease and special systems (oxygen, fuel-gas, vacuum, nitrogen).This design guide focuses on domestic water systems, primarily cold water. Hot water is notincluding in this design guide. This design guide focuses on the domestic water piping, plumbingfixtures, valves, booster pumps and other miscellaneous design issues related to the design ofdomestic cold water systems.3.2Water Supply Fixture UnitsPrior to sizing a domestic water system and determining pipe sizes it is important to understandthe concept of fixture units. Water Supply Fixture Units (WSFU) is the standard method forDomestic Water Systems-5http://www.engproguides.com
estimating the water demand for a building. This system assigns an arbitrary value called a WSFUto each fixture in a building, based on the amount of water required and the frequency of use.For example, a water closet (tank) is assigned a WSFU of 2.2 fixture units (FU) while a sink(lavatory) is assigned 0.7 FU. These values are based on the International Plumbing Code WaterSupply Fixture Unit table. The difference in fixture units is due to the fact that a toilet requiresmore water than a sink. The frequency of use between a private sink and a water closet would bethe same, since a person will normally use the water closet and the sink within the same bathroomvisit. A public water closet has a WSFU value of 5.0. Even though the water closet (tank) is thesame as the private water closet and uses the same amount of water, a public water closet has ahigher WSFU value. The public water closet has a higher usage frequency, which increases theWSFU value.IPC: The international plumbing code or IPC uses the following water supply fixture unit table.Fixture (Source IPC 2006)ColdBidet, PrivateDishWash‐PrivateDrinking FountainKitchen Sink, PublicKitchen Sink, PrivateLaundry Tray, PrivateLav, PrivateLav, PublicService SinkShower, PrivateShower, PublicUrinal, 1" Priv, FlushUrinal, 3/4" Priv, FlushUrinal, Public, TankWash Mach Lg, PubWash Mach Sm, PubWash Mach Sm, PriWC, Pri, TankWC, Pri, FlushWC, Pub, TankWC, Pub, FlushBathroom group, private, flush tankBathroom group, private, flush valveBathtub, private, faucetBathtub, public, faucetCombination fixture, private, 1.003.002.25Domestic Water .com
The water supply fixture units are distinguished between cold, hot or both. If a plumbing lineserves only the cold water side of a fixture, then the corresponding value should be used. Forexample, a main line may serve the both cold and hot water, but then a branch line may go to thehot water heater. The branch line would only use the hot water value.If a plumbing fixture is not available in the table below, then a fixture unit value can be assigned bythe designer or engineer. Typically, a similar plumbing fixture that has a similar maximum flow rateand frequency of use will be selected. If the plumbing fixture will be on for long periods of time,then the volumetric flow rate can be inserted into the domestic water piping calculator.4.0 DOMESTIC WATER PIPE SIZINGThe sizing of domestic water supply system must be based on the minimum pressure available forthe building in question. The designer must ensure that the required pressure is maintained at themost hydraulically remote fixture and that proper and adequate quantities of flow are maintained atall fixtures. In addition, the designer must ensure that reasonable velocities are maintained in allpiping. The velocity of water flowing in a pipe should not exceed 10 feet/sec and should bedesigned for 7-8 feet per second or less, because high velocities will increase the rate of corrosionleading to pipe failure and cause undesirable noises in the system and increase the possibility ofhydraulic shock. The designer should compute and/or know the following:1.2.3.4.5.6.7.Hydraulically remote fixtureAvailable main pressurePressure required at individual fixturesStatic pressure losses (height of highest fixture relative to main pressure)Water demand (total system, and each branch, fixture)Pressure loss due to frictionVelocityHydraulically Remote Fixture: The most remote fixture is the fixture that is the furthest distanceaway from the main domestic water supply point. The most hydraulically remote fixture is thefixture that is not necessarily the furthest away but the fixture that will have the least pressuregiven the projected water demand.Available Main Pressure: The civil or fire protection engineer will typically investigate the mainwater pressure available at the project site. This pressure will determine the starting point for thepressure loss calculations. If there is insufficient pressure available to meet the pressure requiredat the individual fixtures, then a booster pump will be required. In addition, if the pressure is toohigh, then a pressure regulating valve will be required. High pressures at the plumbing fixture canlead to unsafe operation and unnecessary water loss.Pressure at Individual Fixtures: The mechanical engineer should research the plumbing fixturesand determine the required pressure. For example, tank water closets only require 5 psig, whileflush valve water closets can require 15 psig. Each plumbing fixture will have a different pressurerequirement. Even different manufacturers of similar plumbing fixtures will have a differentpressure requirement.Domestic Water Systems-7http://www.engproguides.com
Static Pressure Losses: The static pressure losses are found by taking the difference between theinitial elevation at the available main pressure point and the final elevation at the hydraulicallyremote fixture.Friction Loss: The friction losses are determined by finding the flow rate, velocity, pipe size, piperoughness for the entire hydraulically remote run. Friction losses can be due to the viscous forcesof fluid flowing through the pipe and similar losses through fittings like elbows and tees. Lastly,friction losses are also due to miscellaneous equipment like water meters, valves, backflowpreventers, pressure regulating valves, etc.Water Demand: The water demand is the projected flow rate. The projected flow rate is based onthe water supply fixture units and any other continuously operated fixtures. The water demand isimportant because as the water demand increases, there will be an increase in friction losses.This will reduce the pressure at the hydraulically remote fixture. Thus, the water demand must bechecked along with the pressure at the hydraulically remote fixture.Velocity: Based on the water demand, the projected velocity can also be found. The velocitywithin the piping must be limited in order to avoid excessive noise, water hammer and increasedpipe erosion.4.1MAIN AND BRANCH PIPING SIZINGIt is very difficult to quickly obtain the velocity, water demand, friction loss and static pressurelosses within a piping system, just to size the plumbing lines. Often times, estimates are used tosize the main and branch piping, which can lead to inaccuracies and increased pressure losses oroversized piping. These estimates typically consist of a table of copper pipe sizes and themaximum fixture units that each pipe size can serve. The designer will sum the WSFUs that areserved by each pipe and then choose a pipe size that can accommodate the total WSFUs.This process is exactly the same as the previous process, with a table and the maximum WSFUsfor each pipe size. Except, the table can be customized for any pipe material, tank or flush valveand for any range of velocities and pressure drops. The previous process determined themaximum WSFUs for a pipe size based on some random velocity limitation and/or pressure losslimitation. However, higher velocities can be accommodated in certain areas where water hammerand noise are not an issue. Higher pressure drops can also be accommodated on piping that isnot part of the hydraulically remote run.In both processes, the piping layout must be completed. The piping layout consists of thegeometrical arrangement of the pipes from the water supply to all plumbing fixtures.4.1.1 STEP 1: DETERMINE WSFUThe water supply fixtures units (WSFU) fed by a pipe is determined by the number of eachplumbing fixture that is connected to the pipe and the governing plumbing code. The plumbingcode establishes the WSFU value for each fixture type. The piping layout determines the amountof each fixture type that is fed by each pipe.Domestic Water Systems-8http://www.engproguides.com
4.1.2 STEP 2: CONVERT WSFU TO GPMThe next step is to convert the WSFU value to gallons per minute (GPM). This volumetric flow ratewill help to determine the pressure drop and fluid velocity within the pipe in the next and final step.The conversion from WSFU to GPM will depend on whether or not the connected fixtures arepredominantly flush valve type or tank type.Flush Valve vs. Tank: This distinction is common of toilets. A tank type toilet uses the tank fluidelevation to forcefully flush the toilet waste through the waste system. After a tank toilet isflushed, a fill line is used to fill up the tank. The fill time is typically around 20 seconds. At aresidence or where there is infrequent use, this fill time is acceptable. However, in a public spacewith frequent use, this fill time is not acceptable. A flush valve toilet is used in these situations. Aflush valve type toilet does not have a tank to provide the pressure to force the waste into thewaste system. Thus, a flush valve toilet will require a much higher minimum pressure.Table 1: This table shows that tank type water closets require less pressure and a lower flow rate than flushvalve type water closets.Flush Valve Water ClosetTank Water ClosetFill Time3 seconds45 secondsGallons per Flush1.6 gallons1.6 gallonsVolumetric Flow Rate 32 GPM 2 GPMMinimum Pressure15 to 25 psi5 psiRemarksNot pressure assistedA pipe that feeds predominantly flush valve type fixtures will have a greater volumetric flow raterequirement than a pipe that feeds predominantly tank type fixtures.Domestic Water Systems-9http://www.engproguides.com
Table 2: This table shows the WSFU to GPM conversion difference between a predominantly tank typeversus a predominantly flush valve type.Predominantly 19.60Predominantly 2035.00Predominantly Flush vs. Tank Type: A group of plumbing fixtures is considered predominantlyflush valve if the group has more than one flush valve for every ten tank type water closets. Othercompanies may use a different determination, but the reasoning is that one flush valve type watercloset has a significant impact to the maximum flow rate for a pipe, as shown by the table thatshowed the fill velocity as 32 GPM versus 2 GPM. If there is a branch run that serves no flushvalve type water closets, then that branch can use the predominantly tank type WSFU to GPMconversion. But all pipes downstream from a predominantly flush valve type branch will need to besized with the same conversion, unless the amount of tank type water closets becomes muchgreater than the amount of flush valve type water closets.4.1.3 STEP 3: QUICK SIZING TABLEOnce the WSFU and the appropriate GPM conversion are determined, then the quick sizing tablecan be used to select the appropriate pipe size. The first step in using this table is to select theDomestic Water Systems-10http://www.engproguides.com
pipe material, pipe sub-type, predominantly tank/valve and the C-value. The pipe materials, Cvalues and sub-types are discussed in a subsequent section in this guide. The tank vs. flush valvetype has been discussed earlier in this section. The C-factor describes the pipe smoothness.Steel pipes are given a C-factor of 100 and smoother pipes have a higher C-factor and rougherpipes have a lower value. For example, copper’s C-factor is typically 135 to 150, CPVC & PVC is150.Pipe MaterialPipe Sub‐TypeTank or Valve?C‐ValueCopperType KValve150Figure 2: The first step in using the custom quick sizing tables is to select the pipe material, sub-type, valveor tank and the C-value.Once the pipe information has been entered, then the next step is to determine what are theacceptable velocities and pressure drops within the pipes. This will vary between each situationand each company. Each company will have its own standards, but below is a brief discussion onthe typical acceptable velocities and pressure drops.Sizing Based on Velocity: The typical ideal pipe fluid velocities for a domestic water system arebetween 4 and 8 feet per second (fps). Less ideal velocities are between 2 and 4 fps and 8 to 10fps. At higher velocities, 6 to 10 fps, there will be increased erosion over time and noise duringoperation. At the lower velocities 2 to 6 fps, erosion and noise will not be a concern, but there maybe a stagnation concern and there will be an inefficient use of money.Velocity Pressure: The pressure drop through fittings is dependent on the velocity pressure, whichis dependent on the fluid velocity. At higher velocities, the pressure drop through a fitting will besignificant and may lead to insufficient pressure at the fixtures. The equation used to solve forvelocity pressure is shown below.1212 1144The pressure drop through fittings is found by multiplying the velocity pressure by a K-factor that isused to characterize the fitting geometry, fitting size and turbulence within the fitting. A typicalfitting is a 90 degree long radius elbow with a K-factor of 0.24. The table below shows thepressure loss of ten 90-degree elbows at varying velocities.Domestic Water Systems-11http://www.engproguides.com
477.8013.8721.6731.2042.47Pressure Drop dueto 10 Elbows (psi)2.088.3218.7233.285274.88101.92Figure 3: A greater velocity will cause increased pressure drop through fittings.A lower velocity is more suitable for pipe runs with a lot of fittings. If there is sufficient pressure,then a higher velocity can be accommodated.Sizing Based on Pressure Drop: The second method used to size pipes is through an acceptablepressure drop per 100 feet. The typical values range from 1.7 to 3.4 psi per 100 feet of piping or 4to 8 feet of head per 100 feet of piping. Less ideal values range from 1 to 1.7 and 3.4 to 4 psi per100 feet of piping. The lower pressure drop range is less ideal because it means the piping isoversized. The upper range is less ideal, because it may lead to insufficient pressure at theplumbing fixtures.The pressure drop is determined through the Hazen-Williams equation. This equation is shownbelow. This equation is not accurate for laminar flow and for extremely turbulent flow. However,this equation is very useful for the typical velocities of 2 to 10 fps and higher velocities.4.52 . ;Value MinVel.2PD1.;Low‐Mid41.7.Upper‐Mid Max810 FPS3.44PSI/100FTFigure 4: The second step is to determine the acceptable pipe sizing criteria. Pipes can be sized based onpressure drop, velocity or both. This part of the calculator allows you to pick your preferred range in greenand your acceptable range on the high side and low side in yellow.Domestic Water Systems-12http://www.engproguides.com
1/4 ANANANANANANANA3/8 8NANANANANANANANANANANANANANANANANANANANANANA1/2 74NANANANANANANANANANANANANANANANANANANANANA5/8 .697.62NANANANANANANANANANANANANANANANANANANA3/4 .775.547.469.49NANANANANANANANANANANANANANANANA1 in1‐1/4 2.272.392.492.592.692.803.323.86Figure 5: This figure shows a snippet of the quick sizing table based on the previous inputs. The greenindicates a velocity or pressure loss value within the ideal range. Yellow indicates a value within theacceptable but not ideal range.The pressure drop values are not as accurate for the lower and higher velocities. This is becausethe quick sizing calculator uses the Hazen Williams equation as opposed to the Darcy Weisbachequation.4.2FIXTURE PIPING SIZINGThe pipes that directly feed the fixtures are sized based on the table below. These pipes are therough-in pipes that connect to the branch pipes. Do not get this pipe confused with the fixtureconnection pipe. The fixture manufacturer will indicate
This design guide focuses on domestic water systems, primarily cold water. Hot water is not including in this design guide. This design guide focuses on the domestic water piping, plumbing fixtures, valves, booster pumps and other miscellaneous design issues related to the design of do
piping classes and the numerous piping specifications necessary to fabricate, test, insulate, and paint the piping systems, is titled either the piping material engineer or the piping spec(ification) writer. 1.2. Job Scope Whatever the title, the piping material engineer (PME) is a very important person within the Piping Design Group and .
2.1 Definition of water requirements, water demand and water consumption 3 2.2 Capacity of the Nairobi Water Supply System 3 2.3 Water consumption by user categories 4 2.4 Domestic water consumption 5 2.5 Characteristics of domestic water use 7 2.6 Trends in domestic water consumption in Nairobi 7 I S1JRVI YOF DOMESTiC WATER CONSUMPTION 10
www.DaikinApplied.com 9 AG 31-011 REFRIGERANT PIPING DESIGN. Piping Design Basics. Good piping design results in a balance between the initial cost, pressure drop, and system reliability. The initial cost is impacted by the diameter and layout of the piping.The pressure drop in the piping must be minimized to avoid
liquid process piping systems, engineering calculations and requirements for all piping systems, basics of metal piping systems and thermoplastic piping systems. In Part 2 - the course will continue from Part 1 and review the basics of Rubber and Elastomer Piping Systems, Thermoset Piping Systems, Double Containment
R403.5.3 Hot Water Pipe insulation (Prescriptive) 44 IECC 2015 Hot Water Pipe Insulation of R-3 required for 1) hot water piping ¾ inch nominal diameter and larger 2) for piping serving more than one dwelling unit 3) Piping located outside conditioned space 4) Piping from water heater to distribution manifold 5) Piping located under a floor slab
ASME B31.1, Power Piping ASME B31.3, Process Piping ASME B31.9, Building Services Piping AWWA Standards C200, C206, C900. 3.2.1 Piping Design Criteria Selection of inappropriate codes, standards, and requirements could add to the cost of design and construction. Thus, selection of piping standards such as ASME B31.1, B31
2.4 blast and fire strategy for piping 29 3 design of piping against explosions 35 3.1 introduction 35 3.2 interaction of piping with other design disciplines 35 3.3 loading components acting on piping due to explosions 42 3.4 types of piping and material properties 53 3.5 response of piping to blast loading 57 3.6 acceptance criteria 61
AWWA Manual M49 ix Preface The purpose of this manual is to present a recommended method for calculating operating torque, head loss, and cavitation for quarter-turn valves typically used in water works ser-vice. It is a discussion of recommended practice, not an American Water Works Association (AWWA) standard. The text provides guidance on .
