High viscous gear pump

[M.D.]

I have 25,000 cp viscous liquid, I started transferring this liquid with a gear pump at 18 Hz with 1400 gm/sec output, after one week the output is decreased so I increased it to 50 Hz and got 700 gm/sec and with time it is decreased day after day to 300 gm/sec. I opened the line and checked the pump and have not notice any difference. How can I solve this issue?

 

[LittleInch]

I suspect the effective diameter of the hole inside the pipe is reducing over time.

Has temperature changed?

what size pipe? Velocity? Pressure? Pipe length?

But 25,000 cP is incredibly thick and close to solid.

If the temperature is not uniform then I suspect you are just solidifying the material on the outside of the pipe and effectively getting a smaller and smaller tube in which to try to push this material.

If you've increased the gear ump speed and flow is going down then your relief valve / recirculation line must be going at a higher and higher flow. Have you checked the pressure setting of this valve / relief system?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TugboatEng]

If the pump is cavitating due to restricted inlet flow that would account for increases pump speed and lower flow.

 

[LittleInch]

Good point - have you tried slowing the pump down instead of speeding it up?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.