W. P. Law, Incorporated - Fluid Handling Professionals

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Friction loss in piping refers to the amount of pressure that is lost as water moves through the piping.  As the pipe diameter decreases or flow increases, the amount of friction loss or pressure drop increases as well.  There are two ways to conserve pressure in piping systems.  The first way is to decrease the flow rate of the system.  If this is not a viable option, you can also increase the diameter of the pipe as a means of conserving pressure.

Below are charts for friction loss (pressure loss) for different types and diameters of pipe at various flow rates.  The left side of the column shows various flow rate expressed in gallons per minute.  Along the top of the chart are the different pipe sizes.  Underneath each pipe size is the velocity of the fluid in motion expressed in feet per second (ft/sec) and pressure loss per 100' of pipe. 

The shaded area of the chart shows where the velocity exceeds 5 feet per second.  Avoid using pipe sizes and flow rates that fall within this area as this exceeds the maximum safe flow for piping systems.

If you already know the flow rate of your system, the type of pipe used, and the length, then you can enter that information into the Piping Friction Loss Calculator to automatically calculate the pressure loss.

Class 160 PVC (SDR-26) 
Schedule 80 PVC
pdf icon  Sizes 1/2"-5"    pdf icon  Sizes 1/4"-3"
pdf icon  Sizes 2.5"-16" pdf icon  Sizes 2.5"-16"
Class 200 PVC (SDR-21) 
Type K Copper
pdf icon  Sizes 3/4"-8" 
pdf icon  Sizes 1/2"-3"
Schedule 40 PVC  
pdf icon  Sizes 1/2"-5"
pdf icon  Sizes 2.5"-16"


Pipe Friction Loss Calculator
pdf icon  Download Excel File

pdf icon

Pipe Dimension Guides

These guides are for common pipe types and sizes and are for reference only.  All dimensions should be checked with the manufacturer and are subject to change.

pdf icon  SDR 21 - SDR 26 Specs
pdf icon  Sch 40 - Sch 80 Specs
pdf icon  Pipe OD Guide

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Glue Information

Whether you have PVC, CPVC, or ABS piping, make sure you get the right cement and primer for the best joints.  The links below will help you select the best cement for your application as well as give you vital information on cure times and applications.

pdf icon  Cement and Primer Selection Guide
pdf icon  Glue Set Times and Number of Joints per Quart
pdf icon  PVC Glue Types
pdf icon  CPVC Glue Types
pdf icon  ABS Glue Types and ALL Primer types
Trying to find a gasket for your aluminum pipe, but can't remember what type you have? Check out our catalog pages on aluminum pipe gaskets and find exactly what you're looking for.

pdf icon  Aluminum Pipe Gasket Catalog Pages

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