Recommendations for a high pressure pump- min 60 GPM and 2700 head-ft

[pa5tabear]

I'm replacing an old high pressure water pumping system. The current system uses two identical pumps (one main and one backup). The current pump specs:

Capacity (GPM): 60
Head (ft): 2370
Speed (RPM): 4380

Power: 40 HP
P.F.: 36%
Load eff: 92%

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Is that power draw standard for the capacity and head? I'm trying to figure out how our current pumps compare to new pumps.

Thanks

 

[DubMac]

Your HP formula would be HP = (GPM*TDH*S.G.) / (3960*Eff.)

What style of pumps do you have now?

 

[pa5tabear]

Is the 3960 a unit conversion factor?

We have RotoJet centrifugal pumps.

 

[DubMac]

Yes it is. It would be 1714 using PSI instead of feet of head (for a PD pump).

 

[LittleInch]

I'm a little lost as to what your question is. Compare what - duty? efficiency? power input? Can you explain a bit more please.

On the info provided What is PF? What is efficiency of your pump at that duty point?
Do you have the pump details, i.e. pump curve. If not you could well get them from the vendor = they have records going back a long way. Is that USGPM?

4380 rpm seems quite high. Is it on the end of a VFD motor or have you some sort of gearbox as 60htz 2 pole motors only run at about 3600 rpm. Gearboxes which will have their own efficiency impact.

The equations provided above are for shaft power required by the pump. Your motor will need more electrical power which is divided that figure by the efficiency of the motor (for that size typically 90 to 95%). The efficiency referred to by dubmac is the efficiency of your pump at that duty point.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Artisi]

What is wrong with replacing the pumps with RotoJets again?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[pa5tabear]

Nothing is wrong with replacing the pumps with RotoJets. I just want to at least consider alternatives.

And yes, I'm curious if ~20 year old pumps can be competitive with today's pumps in all areas. Has pumping technology progressed significantly in that time?

 

[LittleInch]

Last 20 years... You now tend to get exactly what you ask for with very little spare capacity or "meat" in any component so you can't rely on the pump coping with extra flow or being abused quite as much as you used to. Just create a table with all your variables you have now and the new pumps to see, e.g. head, flow, efficiency, motor power, weight,etc and then you'll get a better feel for it.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way