Standby pump suction pressurized
Standby pump suction pressurized
(OP)
Have you ever seen the suction of a standby pump being pressurized up to the discharge pressure of the running pump?
Could this happen if the standby suction line is closed and its discharge line open, regardless of the check valve presence?
In this case rating of suction side instruments (low flow & pressure switches) should be that of the discharge side?
Regards,
Could this happen if the standby suction line is closed and its discharge line open, regardless of the check valve presence?
In this case rating of suction side instruments (low flow & pressure switches) should be that of the discharge side?
Regards,





RE: Standby pump suction pressurized
Don't know.
And the suction flange pressure rating must also equal the discharge flange rating.
"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization
RE: Standby pump suction pressurized
Now the question is why most pump systems have their suction side designed according to max suction pressure and not discharge pressure.
Can we regard on operating procedures to avoid increasing suction rating?
RE: Standby pump suction pressurized
If you have two equal pump stations connected by a flat pipeline, a shutdown of the second's discharge pipeline while the first keeps running will cause full dischare pressure of the first station to reach the second pump station's suction line.
A recycle line from a pump's discharge line back to its own suction line might easily cause suction side overpressures when the recycle line's valve opens too much.
If you can have these or a similar scenario, you must protect a lower rated suction flange by a relief valve, or upgrade the suction inlet to equal that of the discharge side. Its important to specify the maximum possible suction pressure that can reach the pump. On smaller units, both suction and discharge ratings could easily be the same, but its not always the case for large power units. I've had pumpswith maximum suction pressure ratings equalling only 1/4 of the discharge pressure rating.
"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization
RE: Standby pump suction pressurized
RE: Standby pump suction pressurized
Please try to stay out of trouble.
"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization
RE: Standby pump suction pressurized
RE: Standby pump suction pressurized
fdomin, Sorry for the hijack, but that was important.
"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization
RE: Standby pump suction pressurized
This commonly crops up during HAZOPs of manifolded pumps generally leading to suction flanges and inlet block valves being uprated to discharge ratings. It is usually caused by anticipated leakage back through discharge check valves.