# Pump Selection/Head Calculations

GishEng
Hi everyone, I am in the process of putting together a water feature and am having trouble selecting the correct pump for the job. The pump will be required to pump water to a vertical distance of approx 7.4 meters. A submersible pump would be best. The pipe coming up from the pump is 12mm in diameter and has four 90 elbows and one globe valve. From my calculations based on the head loss due to the elbows, friction and the valve I require a pump with a maximum head of around 35.4 feet. A side question, if the output on my pump is 1 inch let's say and I put in a pipe reducer directly after the pump which reduces the diameter of the pipe from 1 inch to ½ inch how will that effect the flow rate/pressure and the max head achievable by the pump?
Any help would be great!
Best Regards,
Josh

## Answers and Replies

Staff Emeritus
A side question, if the output on my pump is 1 inch let's say and I put in a pipe reducer directly after the pump which reduces the diameter of the pipe from 1 inch to ½ inch how will that effect the flow rate/pressure and the max head achievable by the pump?
The reducer will decrease the flow rate. It will increase the pressure upstream of the reducer and decrease the pressure downstream. (If the reducer feeds a 1/2 inch pipe, then the same thing applies, lower flow, lower discharge pressure at pipe end.