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In one of my application, there is a requirement to dispense the concrete paste at the required rate continuously. some technical details of the application given below

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  1. Dispense rate 5-50 LPM
  2. Dispense should be continuous
  3. The material is concrete paste
  4. Solid content is up to 4 mm
  5. delivery length is 5-6 meters
  6. bends - 3
  7. Hose dia 38 mm
  8. density 1.9 to 2.2

Currently, I am using a screw pump, which can pump up to the full length of 5-6m. But with some issues.

  1. The flow often stops, for which we had to reverse the motor few rotations and then run forward. But this operation is not acceptable.

  2. The materials flown out of the pump was heating up by 8-10 deg.C.

We have also tried the piston pumps that are used in construction sites for concrete spraying operation. It works continuously, but there are no linear flow rate adjustments, and it is bigger in size.

The screw pump works fine, but it often stops. The reversing and restarting pumping operation is not desirable for the process. We noticed that when reversing the motor for few rotations, the material in the hopper is raising. So we are guessing that the motor is stopping due to air trap. But supplier commenting it is because of vacuum created in the pump. because the concrete paste is not perfect fluid.

Are any screw pump users came across such situations? How did you solve it? Any suggestions to fix this issue I can get to rectify it??

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    $\begingroup$ Try re-designing the hopper to make sure that the concrete "flows" easier into the pump - as that seems to be the issue you are describing... $\endgroup$ – Solar Mike Dec 14 '18 at 8:32
  • $\begingroup$ There is no problem in the material flow to the inlet. $\endgroup$ – Aayvu.com Dec 19 '18 at 3:15
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Your pump is having difficulties to suck from hopper. That's because the material in hopper is not fluid enough, not enough weight to push material down the inlet throat, so it depends on suction effect - but eventually suction effect is not functioning when a hole created down to screw impeller. My suggestion is to have better screw pump design (Hopper facing open top, screw to down, with extended screw sticking out from inlet throat to hopper, hopper taper should steep more than material slide angle).

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