4 replies to this topic

[Swami nallam]

sir,

in our industry we use plunger pump to flow reactants to PFR  ,the reactants(h₂so₄₎ are acidic and we need nearly 15 kg/cm²  pressure at reactor ,but problem is with pump Non return valve , pump nrvs are damaging so we are thinking to put a nrv at pump discharge and it should be suitable for acidic flow and withstand high pressure, i need some suggestions on selection of nrv or any remedies to solve this problem

 

 

[fallah]

 

Swami nallam,

 

I think you're not basically allowed to use a NRV along the discharge line of a positive displacement pump instead its damaged NRV at the pump outlet. In fact, mentioned pump should be repaired if it's possible otherwise the pump should be replaced with a new one.

[Art Montemayor]

A positive displacement, plunger pump employs both a suction and discharge valve - both of which are nothing more than check valves (or what some people call non-return valves, NRVs).  Therefore, you already have two NRVs already functioning (in series) within your plunger pump.  I have often used additional check valves on the discharge of plunger pumps that have delivered 3,000 psig+ of pressure.

 

The operation of check valves in series is nothing new nor novel.  Many HazOps problems with backflow hazards are resolved with multiple check valves installed in series.  I see nothing wrong with the mechanical operation of installing check valves in series in the discharge line of a plunger pump.  Operationally, however, you may have problems with the stored acid in between the various check valves and I recommend that you supply manual drain valves in those sites to allow inspection, maintenance and replacement.

[Swami nallam]

Naser Fallah sir,

 

Thanks sir,

 

But the NRVs of pump damaging frequently and we dose acid at discharge static mixture our technical services are saying that acid is coming back to pump so nrvs of pump are damaging to avoid that we are thinking to put new NRV which suitable for acids withsatand high pressure    

[fallah]

 

But the NRVs of pump damaging frequently and we dose acid at discharge static mixture our technical services are saying that acid is coming back to pump so nrvs of pump are damaging to avoid that we are thinking to put new NRV which suitable for acids withsatand high pressure    

 

Swami nallan,

 

All PD pumps, including one in your case, if well designed and manufactured in mechanical and material standpoints should suffer the high pressure at the discharge and shouldn't be frequently damaged in its discharge check valve. Then, i think, happening of mentioned damages is an indication of poor design and/or material selection.

 

I believe, applying an additional check valve at discharge line not only will result in no negative issue but also might increase the pump performance; but the main point is: if two check valves at suction/discharge lines could provide the adequate effectiveness for proper pump operation why the check valves are integrally included in pump structure in pump manufacturing stage?

 

Anyway i think the pump should be repaired and even replaced with proper one if the repair is impossible; and then additional check valve at discharge line being used for more effetiveness and reliability...