sump pump selection 2

[mirghaffari]

hi all,
Iam requested your assistance to advise me for selection of suitable pump for following application. Please consider both performance and economic aspect for this issue.

LIQUID CHARACTERISTICS:
1- Service : HEAVY/LIGHT CRUDE OIL
2- Viscosity: 24~92 CP
3- Flow: 20m3/hr
4- Diff. head : 33 m
5- Pump is submerged in Drain Drum (sump pump)
6- Application : INTERMITTENT

I am doubtful about selection of suitable sump pump (VS1,VS2 or VS4 )? Could you please help me to select suitable type with considering the economic aspect?

 

[1gibson]

VS4 with product lubricated bearings (small line of tubing from discharge to lineshaft bearings.) Operate it on a float switch, no mechanical seal.

Between the lack of a seal, and typical pricing, you could get two VS4's for the price of a VS1. That will give you a warehouse spare at OEM cost, if you have the space to store it you should consider this for a number of reasons.

 

[mirghaffari]

thanks a lot 1gibson,Your answer is very helpful.

do you mean tnat it is better i select two VS4 pumps (1+1 spare) insted of one VS1 pump for this application?
it mean that VS1 pump is more expencive than VS4? do I understand what you mean exactly?

and second question: is it possible to select the pump without the mechanical seal?

thanks again

 

[1gibson]

Exactly, and yes a VS4 pump does not require any sealing arrangement in an open sump, as long as the high liquid level is below where the pump is mounted. The discharge pipe is separate from the column pipe, and the column pipe is not pressurized. This type of service is exactly what VS4 pumps are made for.

Make sure you do not have a pump specification that calls for a mechanical seal! A pump vendor will sell it to you and once they do, it is hard to convince anyone to delete it. The pump salesman will want their commission because seal and seal system will be a big part of the order value, and the customer will not want to face the fact that they authorized thousands of dollars on non-essential equipment.

Nobody will listen to the engineer that says "you all know that this seal doesn't do anything, right?"


In some cases a seal is required (mounted in a pressurized tank, health hazard, etc.) but it only seals against the suction pressure.

 

[mirghaffari]

Dear 1gibson,
Your answer was very thorough and helpful.
thank you