Why are vane pumps common in diesel fuel service?

[ICLL]

I'd like to understand why vendors offering diesel fuel storage / handling / dispensing systems seem to prefer to offer positive displacement vane pumps, rather than centrifugal pumps.

I can understand the requirement for a self-priming pump when intermittently taking suction from a top entry nozzle e.g. on a self-bunded storage tank. I realise a centrifugal pump would not self-prime if priming was lost.

But are there any other reasons why a centrifugal pump would not be adequate in this type of service? The vendor can't explain; his attitude is just "that's what we normally sell".

Any thoughts?

 

[BigInch]

Do they measure volume off rotation count?
And possibly because vanes work better with entrained air and LPGs.

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"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[ICLL]

I guess that the ability to measure flow after a fashion using the pump could be an advantage. Maybe you could avoid the need for a separate flowmeter if high accuracy was not required or money was not changing hands. I'm not convinced this would be the main reason.

With regards to "working better with entrained air and LPGs", in what way do PD pumps "work better"?

And why is there a need to even consider entrained air? Is it because diesel storage systems are intermittent in operation and have disconnectable hoses where air may possibly be introduced from time to time?

Bear in mind my frame of reference is hydrocarbon process plant which usually runs continuously, air is not introduced, and lines and pumps usually run full and under pressure.

 

[BigInch]

Vane pumps have high differential pressures, high efficiencies and apparently suffer less from cavitation from the higher vapor pressure liquids (not a problem for diesel). Some manufacturers claim up to 50% vapor can be handled, where std. centrifugals start losing eff at 5% or so. The closer you are to draining and filling end user smaller tanks, the more problems you can expect with entrained air, no matter what liquid you're working with.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[TenPenny]

One advantage I can think of is that the vane pump will give a relatively constant flow, at a constant speed, independent of tank level or viscosity. (Note use of word relatively).

While that may not be precisely important, it does make for a nicer operation.

 

[MikeHalloran]

Vane pumps also don't lose much flow when the filters start to clog.




Mike Halloran
Pembroke Pines, FL, USA

 

[Unotec]

And the fuels will tend to foam less due to the shear from the centrifugal pump. Nothing prettier that a tank overfilling with foam

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[zeusfaber]

How much of it is about cost and "because you can"?

A.

 

[MikeHalloran]

None of it is about cost.

One more factor: When the weather gets cold and Diesel turns to wax, a centrifugal pump won't move it. A vane pump has a better chance.





Mike Halloran
Pembroke Pines, FL, USA

 

[ICLL]

Thanks very much for all the suggestions. Any others?