How do I Convert Pressure Loss Through Copper Fittings to Head Pressure?

A pipe tee has an associated pressure drop.

Head pressure refers to the amount of resistance a pump must overcome to move water throughout any given system. Water slows down due to frictional resistance, which comes from all equipment in the system such as pipes, valves, fittings and coils. In order to measure the necessary head pressure, you must take into account all the pressure loss throughout the system. In order to calculate you must have all measurements in terms of head pressure.

Things You'll Need

• Paper
• Pencil or pen
• Calculator

Instructions

Calculating Equivalent Head Pressure

1. Learn the pressure loss of each piece of equipment or fitting. Manufacturers list pressure losses, or drops, of their equipment based off a pipe velocity of 4ft/sec.

2. Add up all the pressure drops of every fitting and piece of equipment in your system. For example, if you have 4 tees at .5psi, 2 elbows at .25psi, and 1 valve at 1psi, you will then have a total pressure drop of 3.5psi.

3. Convert the pressure drop to head. You measure head in feet as opposed to pressure, which you measure in PSI. One PSI equals 2.31ft of head. This means that a water column with one pound per square inch acting upon it will rise 2.31 feet. Take your pressure drop and multiply it by 2.31; this will give you your head pressure. In the example, 3.5psi equates just over 8 feet of head.

Tips & Warnings

• Don't overthink it. It is a simple conversion of PSI to feet.

• Keep in mind that additional pressure loss comes with the length of pipe. Your pipe length multiplied by 4ft/100ft will give you an equivalent pressure drop due to length of pipe. You must add this to figure out the head requirement of your pump.

References

• Engineering Toolbox: Converting Head to Pressure