Selecting an Axial Piston Pump for a 1000m Manned Submersible Application

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Discussion Overview

The discussion revolves around selecting an appropriate axial piston pump for a manned submersible application at a depth of 1000m, focusing on the pump's specifications, including required pump head, power input, and flow rate. Participants explore the implications of these requirements and alternative methods for buoyancy control.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant states the required pump head is approximately 410m and power input is about 18,000W, seeking recommendations for a suitable axial piston pump.
  • Another participant argues that 18,000W may be excessive if the purpose is merely to maintain constant depth, suggesting the need for clarification on the application.
  • Questions are raised regarding the flow rate, with one participant providing a flow rate of 50 l/min or 0.000833333 m³/s.
  • Concerns are expressed about the weight of pumps that meet the power specifications, with one participant noting that a suitable pump found online was excessively heavy.
  • Alternative methods for buoyancy control are proposed, including the use of compressed gas, with a participant mentioning the pressures of nitrogen and SCUBA tanks.
  • A caution is raised about the risks associated with using compressed air, referencing historical incidents related to submarine operations.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of the specified power requirements and the application of the pump. There is no consensus on the best approach or solution, and the discussion remains unresolved regarding the optimal pump selection and buoyancy control methods.

Contextual Notes

Participants highlight the need for clearer assumptions and calculations regarding the operating requirements, indicating that some foundational aspects may not have been fully addressed.

ENGBIO
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So I posted yesterday about appropriate pumps for pumping water out of a ballast tank in a manned submersibles at a depth of 1000m. I decided to switch to an axial piston pump. I got that the require pump head is approx. 410 m and the required power input provided by the pump is approx. 18 000W. My inlet diameter is 2.6 cm and my outlet diameter is 2 cm.

What would be a good axial piston pump I could use?

Thanks!
 
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ENGBIO said:
So I posted yesterday about appropriate pumps for pumping water out of a ballast tank in a manned submersibles at a depth of 1000m. I decided to switch to an axial piston pump. I got that the require pump head is approx. 410 m and the required power input provided by the pump is approx. 18 000W. My inlet diameter is 2.6 cm and my outlet diameter is 2 cm.

Whoa! 18000 watts is far too much if your purpose is only to maintain constant depth with a "trim tank". But if you're talking about diving and surfacing that's a different thing.

What is the flow rate in gallons or ft3 or m3 per second?

One you know the pressures, the flow rates, and the power requirements, why can't you just search the Internet for pumps meeting your specifications? Learning how to use research tools available to you may be part of the lesson your professor wants you to learn.
 
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ENGBIO said:
So I posted yesterday about appropriate pumps for pumping water out of a ballast tank in a manned submersibles at a depth of 1000m. I decided to switch to an axial piston pump. I got that the require pump head is approx. 410 m and the required power input provided by the pump is approx. 18 000W. My inlet diameter is 2.6 cm and my outlet diameter is 2 cm.

What would be a good axial piston pump I could use?
In the previous thread you never nailed down the assumptions much less calculated the operating requirements. Please post a summary of the work you've done to get those answers so we know we aren't just providing meaningless help to move forward with bad critera/calculations.
 
anorlunda said:
Whoa! 18000 watts is far too much if your purpose is only to maintain constant depth with a "trim tank". But if you're talking about diving and surfacing that's a different thing.

What is the flow rate in gallons or ft3 or m3 per second?

One you know the pressures, the flow rates, and the power requirements, why can't you just search the Internet for pumps meeting your specifications? Learning how to use research tools available to you may be part of the lesson your professor wants you to learn.

Hi Anorlunda! My flow rate is 50 l/min or 0.000833333 m^3/s. I did look look online for a dc pump to meet my specifications but the one I found for that power was like 800 lbs lol...So I thought perhaps I was doing something wrong but I guess for that amount of power it would be quite large? Its odd though because how would small manned submersibles be able to accommodate such massive motors.
 
russ_watters said:
In the previous thread you never nailed down the assumptions much less calculated the operating requirements. Please post a summary of the work you've done to get those answers so we know we aren't just providing meaningless help to move forward with bad critera/calculations.

Yes, I apologize I didnt want to clog up the post with my calculations but I'll try to be clearer next time
 
OK, I must have been wrong in what your application is. I thought it was just trim to maintain constant depth.

An 18kw BLDC motor is similar to those used in electric cars. A quick search for those on alibaba showed some 20 kw weighing 39 kg. It might be similar to the motors used for propulsion.
 
How about using compressed gas instead of a pump for gross buoyancy control. A full compressed Nitrogen tank is at 2200psi and a high pressure SCUBA tank is in the 3300-3500psi range.
 
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A caution: be sure to thoroughly dry such air lest an urgent tank-blow cause icing in the lines...
IIRC, this was the probable cause of tragic loss of submarine USS Thresher...
 
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Nik_2213 said:
A caution: be sure to thoroughly dry such air lest an urgent tank-blow cause icing in the lines...
IIRC, this was the probable cause of tragic loss of submarine USS Thresher...
Ahh! So that's what did it. Good thing to note.
 

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