Centrifugal Pump By-Pass orifice
Centrifugal Pump By-Pass orifice
(OP)
Looking for the correct way to size a constant flow by-pass orifice for a centrifugal pump application. Old rule of thumb was 25 gpm per 100 horsepower. Any additional comments??





RE: Centrifugal Pump By-Pass orifice
http://www.mcnallyinstitute.com/CDweb/o-html/o003_1.htm
however, i also recommend validating the need for the orifice before installing it and obtaining needed information from the pump mfg.
good luck!
-pmover
RE: Centrifugal Pump By-Pass orifice
It seems to be very low for minimum flows currently recommended by vendors. I've just put in a bunch of API pumps, all relatively low head (100 to 300 feet) and up to 1200 gpm or so and the recommended minimum flows were around the 25% or so, some pushing 40%.
At those flows, an orifice is typically not economical due to the continuous energy use and additional pump capacity needed to account for the flow through the orifice 100% of the time. If the fluid is clean, Yarway's ARC valves work well. If not, a traditional minimum flow loop using a meter and control valve is likely easily justified on economics.
If you want to post the head, flow, SG, configuration (single suction, double suction, etc) and speed, I can do a quick calc using an approach I have. It's gives a recommended minimum flow comparible with the numbers I gave in paragraph 2.
RE: Centrifugal Pump By-Pass orifice