Submergence of dry motor submersible pump 1

[m15]

When i came across the dry motor submersible pump the motor has a limitation that it cant be used above 20m.whereas the wet motor submersible pump can be used till 350m.can i know why?pls advice.

 

[BigInch]

see 14 replies to same in electrical-motors.

BigInch-born in the trenches.

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[m15]

I have not got the answer for this submergence hence i posted

 

[BigInch]

Is the answer not the dry housing pressure rating? A dry housing would conceiveably have a limitation of 20 m depth, whereas a wet motor could operate presumedly at much greater depths.

If that's not the answer, I don't know what is. We'll see if anybody else can suggest something different.

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[Artisi]

Same question asked by ng1709 on 24 Nov. Now is this a strange coincidence or just 3 postings for the same question.




Phitsanulok
Thailand

 

[BigInch]

"There is no such thing as coincidence." J. Edgar Hoover

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[d23]

m15:

The answer is the delta pressure. “Wet” motors used in the petroleum industry are installed to depths exceeding 15000 feet (4572 M) without problems. Submerged static pressures > 6000 PSI are not uncommon. The trick is to keep the pressure inside the motor and outside the motor equalized. Dry motors and / or water well type motors are limited by collapse pressure of the motor housing.

D23

 

[BigInch]

Very good point. I wasn't considering collapse pressures, as the maximum depth mentioned by the OP was 320 m, but that is probably getting into the depth range where it needs to start being considered for housings without specially designed reinforcement.

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[EdStainless]

There is also the deltaP across the seals. With oil field type units that are pressure equalized there is no pressure across the seals.

Some water filled water-well motors have limited pressure equalization capacity. They can be used deaper than dry motors, but there are limits.

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