Pressure drop as flow rate increases

Plumbing · Flow and Pressure · printed page 258 (PDF page 259)

Book index entries

Drops as Flow Rate Increases Pressure Drops as Flow Rate Increases Water Supply Pressure Drops as Flow Rate Increases Flow and Pressure of Water in Supply Plumbing Supply Plumbing – Flow and Pressure Water Flow – and Pressure in Supply Plumbing

Text in the illustration

note:
pressure drop shown is across an equivalent pipe length of 100'
each fixture in the house will have a different profile
pressure drop (PSI)
flow rate (gallons per minute)
1/2" pipe
3/4" pipe

Generated explanation

The illustration graphs water-supply pressure drop against flow rate for 1/2-inch and 3/4-inch pipes. A dashed curve with circular data points represents the 1/2-inch pipe, while a solid curve with diamond data points represents the 3/4-inch pipe. Both curves rise as flow increases, but pressure loss is substantially greater in the smaller pipe at the same flow rate. The graph covers flows from 1 to 10 gallons per minute and pressure drops up to 40 PSI. A note specifies an equivalent pipe length of 100 feet and states that each fixture in the house will have a different profile.

Components

1/2-inch water supply pipe 3/4-inch water supply pipe