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Could you tell me what going on ???????????????

Could you tell me what going on ???????????????

Could you tell me what going on ???????????????

Dear sir
 Please be advised pump operation and the result after our supervisor went to your site to investigate and test during June 14-15, 2001 as below :
June 14, 2001    :    Before start the pump, we open valve at port no. 5 for venting and find liquid foaming is occurred all time.  We took 30 minutes time until a little bit foaming is found.  Then we start the pump.  Operating data is as below :
    -    Pressure at suction drum is 15-20 PSI.  Needle of pressure gauge is swing all time.
    -    Suction pressure which pressure gauge is installed at strainer is 8-10 PSI.  Needle of pressure gauge is swing all time.
    -    Discharge pressure is 290-300 PSI.  Needle of pressure gauge is swing all time
    -    Current is 22 Amp.
    -    Pressure of condensate surge drum (Destination drum) is 285 PSI
    -    S.G. of liquid is 0.754
We found the pump can't pump by observation liquid level in suction drum doesn't decrease, and feel hot when tough on suction piping and pump casing.  Then we vent the pump again by opening valve at port no. 5, and find gas blow out.  After that we started the pump, and the result still the same.  We find pump can't pump.  Then we bring sample liquid to fill up on small vessel, we find that this liquid is easy to become foaming.  It become foaming by shaking the vessel.
 June 15, 2001    :    We open suction valve to allow liquid come into suction piping, and pump casing for 1 night, then we vent at positions we expect it may occur air block i.e. strainer, pump casing drain, seal port no. 5, discharge line before discharge valve and discharge pressure gauge.  For this venting, it take about 1 hour to make sure that no any gas in suction piping and pump casing.  After we start the pump, and operating data we record is as below :
    -    Pressure at suction drum V-3610 is 4 PSI
    -    Suction pressure which pressure gauge is installed at strainer is 8-9 PSI
    -    Discharge pressure is 290-300 PSI
 We find the pump can pump for a short period (only 15 second).  It is observed be decreasing of liquid level in suction drum, after that the pump can't pump, although we adjust discharge valve decrease.  During pump operate, we find suction piping, pump casing, and discharge pipe are cool, and water-dropped is found on piping.
 Then we vent piping and a seal port no. 5 again, and start the pump.  For this time, we open part no. 5 all time the pump operate.  It is find foaming is occurred all time, and the pump can't pump.
 For above mentioned symptoms, we expect that your liquid is easy to vaporize.  Only a little bit of pressure or temperature is changed.  It cause your liquid become foaming, or vaporized.  So it occur gas inside the pump casing, and the pump can't pump as final.

RE: Could you tell me what going on ???????????????

What fluid are you pumping, hydrogen peroxide?

RE: Could you tell me what going on ???????????????

No ! just light hydrocarbon (mixed)
Do you know this problem came from not enough NPSH available or not?

RE: Could you tell me what going on ???????????????

The fluid you are pumping is at the saturation point.  The fact that it pumped for a while says that the pump needs whatever height in the suction separator where it stopped.  Yes it is a strong possibility you have an NPSH problem.  You need to check the suction line for pockets, blockage, and if the starining is blocked.  Good luck

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