Dry pit submersible
Dry pit submersible
(OP)
Could a dry pit submersible pump operate under negative suction provided that NPSH and min. submergence of the suction bell conditions are met at the design flows?
I have a situation where I am trying to replace an existing dry pit with a new dry pit submersible. The minimum water level in the wet well is about 16" below the C/L of pump impeller.
I thought it is possible until the new pump manufacturer said that the pump has to be flooded above the volute. This is a 50 hp dry pit submersible pump supplied with cooling jacket.
Thanks
I have a situation where I am trying to replace an existing dry pit with a new dry pit submersible. The minimum water level in the wet well is about 16" below the C/L of pump impeller.
I thought it is possible until the new pump manufacturer said that the pump has to be flooded above the volute. This is a 50 hp dry pit submersible pump supplied with cooling jacket.
Thanks





RE: Dry pit submersible
The fact that it is a dry pit submersible does not make any difference as such, it still just works like a pump. If the old pump worked than another pump can work as well, provided it is the same style and the ratings are correct.
I suspect however that your pump does not have a footvalve assembly so that to start pumping the suction has to be flooded and the pump primed. If the pump does not have a footvalve the suction should always be flooded to a level above the pump volute and the control levels should be adjusted accordingly.
Pumping below the pump volute will be possible but on shut down you risk the pump loosing its prime.
The other issue may be that to meet the rating required the particular pump must have a flooded suction. This may be a particular issue if the pump rates have been upgraded in the past but the suction pipework has remained the same.
Regards
Ashtree
"Any water can be made potable if you filter it through enough money"
RE: Dry pit submersible
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RE: Dry pit submersible
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.)
RE: Dry pit submersible
RE: Dry pit submersible
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.)