Positive displacement pumps - for Slop oil service

[vjr0512]

The contractor suggests for Gear pump instead of Screw pump for slop oil service ( from slop oil storage to mobile tankers filling ). The viscosity of the slop oil is 5 cP and the pumping capacity is 15 m3/hr at a disch. pr of 3 barg.

Is the contractor's claim is technically acceptable? Earlier they only was suggesting Screw pump ( probably they would have meant as progressive cavity pump)but not clear why they are now suggesting Gear pumps... Could be cost?

Thanks to advise.

 

[LittleInch]

Based on the almost total lack of real data you've given, I can't see why either of the two pumps wouldn't be capable of doing the job.

Why the change of mind? No idea, but cost is a possibility.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[vjr0512]

Little inch, the slop oil service pump is suggested to be used in an effluent treatment plant after recovering the slop oil from the waste water. These pumps are to be used to pump the slop oil in mobile tankers for transporting outside the premises. During the FEED stage, it was construed to be Screw pump but during Detail Engineering, it is suggested to use Gear pumps for the same service instead of Screw pump. My question is whether both the type of pumps have equal efficiency but the Contractor says that gear pumps will be more suitable for this service than screw pumps.

Is my information sufficient?

Thanks in advance

 

[LittleInch]

I can't see any reason why either type of pump could not be used.

Only by comparing data sheets could you see which one is more efficient.

The detail designer must have some reasons, but what they are isn't clear. WE all have personal experience and preferences and if it does the same duty it doesn't really matter as far as I can see.

The only issue I can see is whether there are solid bits in the "slop", which is a very vague description of a fluid. If there are then you really want a progressive cavity pump which is not a screw pump. A gear pump really doesn't like grit and solid bits.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RODesigner]

In case of ETP plant, generally there will be a some amount of grit and solid bits. But these will settle down in the tanks and actually when it comes to slop oil transfer, it is fairly free of grit and solids. In such a situation, GEAR pumps are will have better operation and and suitable.

POwer and Water Engg

 

[bimr]

Gear pumps are adequate for this service and will be substantially less expensive than screw pumps.