problem with reciprocating pump

[jangochem]

hi
we have a reciprocating pump for pumping caustic ( 30% conc).d/c pressure is abt 50 kg and flow abt 60 kg/hr .bucket filters are providedin thesuction.the pump fails intermittenly - pumping acton is there but no pumping.No solid entrainment is found in filters.and the funny part is tht pump will start pumping even by a minor blow by an iron rod on the s/c line or pump body.there are similiar pumps handling higher caustic conc in upstream but they r not facing this problem.
Please advise

 

[Compositepro]

Please repost your question in English, you might get better response. d/c, s/c, r are not words or standard abbreviations. kg is not a unit of pressure.

 

[jangochem]

sorry i used the common slang of our workplace.
d/c -- discharge
s/c -- suction
discharge pressure 50 kg/cm2

 

[Compositepro]

About the only thing it could be is a sticking valve.

 

[CH5OH]

one of the suction valves is not seating properly

 

[whammett]

+1 for CH5OH


Will Chevron Corp.

 

[sshep]

Definitely! Either a leaking check valve or internal relief valve.