Gear Pump Designs

<...Is there any limitation of pressure rating i.e maximum pressure can be achieved ?...>

As gear pumps are positive-displacement pumps, the maximum pressure will be limited to the lowest of:

• the setting of a downstream pressure relief valve
• the setting of a downstream pressure trip system
• the structural integrity of the downstream pipework
• the structural integrity of the pump itself, including any slip that might be taking place between the rotors and their sealing surfaces

Guest # 1

<...Is there any limitation of pressure rating i.e maximum pressure can be achieved ?...>

Please allow me to elaborate some other way, I am trying to understand if 180 bar pressure rating gear pump can be designed & operated succesfully for industrial purpose. Ok,piping system do have an impact on system but here only gear pump designing is being taken into consideration.

A 180 bar criterion will influence the shaft design in the withstandable torque department and the seal surface in the clearances design and materials selection departments.

The pump has to be so well made that the gears and seals can rub past each other, with appropriate levels of lubrication from the process fluid, while developing a useful flowrate and pressure in the process. The slacker those clearances, the more difficult the pressure achievement. The tighter, the more of the shaft input gets converted to heat, raising the torque for the same duty point. Then there's thermal expansion to think about....

Then there's thermal expansion to think about....

PWSlack is correct......

the pump is designed to its environment.....in a sanitary envionment the pump has two classes, one with a larger clearance to make up for the thermal expansion.

phoenix911

At 180 bar yes that can be obtained many of the pump manufactures make pumps that are rated to 3000psi(206 bar)max and some to 5000psi(344 bar).

It's the volume at 50 m³/hr that will be a problem. If that is the volume you will need?

The gear pumps are positive displacement pumps, so the volume can be designed by the gear portion and of course the speed (ie RPM) since the gear specifies the incremental volume per revolution or to be precise per tooth movement (where the stored oil is moved).

When you go to the pressure part, the constraints are the seals and the clearances (since more is the pressure, the reverse flow through the axial clearances start creeping in) and of course the seals/ glands too come in picture.

The complication starts when you have high volume and high pressure- since now if you see the power requirement that becomes too high and that limits the size of the gear teeth, shaft, and all other mechanical parts (end of the day, the gear teeth will be transmitting the power so must be designed to be strong enough to withstand it).

50m³/hr = about 830 lpm is a bit high for it and especially if you want it at high pressure

a few links may be helpful

http://www.hydraulicsupermarket.com/upload/db_documents_doc_16.pdf

But the basic design I understand is a bit specialised.

Guest #1

Well, Good reply.

Thanks