sea water lift pump 1

[norine]

we want to install an RO unit with capacity 8m3/day with feed from sea water lift pump 40 m below deck. Is is possible to have in the market such small lift pump ?

thanks

 

[TD2K]

No. Any pump is theoretically limited to a suction lift of about 10m.

 

[Kawartha]

Norine,

When you say below deck, I assume you are referring to an offshore drilling or production platform.

The flow rate of 8 m3/d is very small (a little over 1 usgpm). You could install an enclosing tube from deck to a few feet below the water level, and use this as a casing for a small submersible pump. Size the submersible "deep well" pump for the required head that you require for the RO unit. You can purchase small submersibles in sea water resistant materials.

As TD2K indicated above, you can not suck the water from the 40 m elevation, therefore you have to push it from sea level.

If the pump that you select has a minimum flow rate which is in excess of the requirement for the RO unit, you can: 1) bypass part of the flow back to the source, or
2) you can use a storage tank which would be filled by the pump at a higher flow rate, and shut off until the tank low level switch called for additional water. Tank sizing would be based on maximum number of starts/hour.

 

[d23]

norine

I am not a jet lift person, but with the low flow, low head that you require a form of hydraulic lift may be another consideration. That would keep moving parts on the deck for easy access. By comparison to a sub-pump the efficiency would be low, but a with your low flow requirement I doubt that would make much difference.