STRAIGHT RUN
STRAIGHT RUN
(OP)
FOR WHICH KIND OF PUMPS 5D(PIPE DIAMETER) STRAIGHT RUN PIPE IS MANDATORY AT PUMP SUCTION NOZZLE?
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RE: STRAIGHT RUN
- Many people say 5D is the rule.
- Many people say 10D is the rule.
- Many people are now saying that all pump discharges should have two check valves and these check valves should have 10D upstream of both the first Check Valve and the second Check Valve, plus 5D downstream of the second Check Valve before the Block Valve or elbow.
Now spend a little time looking at the different sized pumps (maybe 8" suction & 6" discharge and larger) we now find in the typical Mega-sized plants and see what the pump piping will look like, then go and sell it to the CEO of your current Client
- The consensus of past installations tells us minimum works and is the most cost effective when considering the cost of Real Estate inside the fence of a plant and the extra cost for pipe supports, stairs or ladders and platform to get over or around the obstructions.
prognosis: Lead or Lag
RE: STRAIGHT RUN
Why not 1 block valve and 1 check valve.
Learn from the mistakes of others. You don't have time to make them all yourself.
RE: STRAIGHT RUN
I've not come across all these check valves, but if you're short of space on the inlet you can always put in a flow straightener - some fit between flanges (google ISO 5167 flow straightener), which are normally accepted as being the equivalent of the straight pipe run
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: STRAIGHT RUN
For dynamic pumps the second check is a waste of money (it does nothing good or bad, just expensive. For non-pulsating PD pumps (like a progressing cavity pump), pulsation is rarely a problem and dual check valves are a waste of money.
David Simpson, PE
MuleShoe Engineering
Law is the common force organized to act as an obstacle of injustice Frédéric Bastiat