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
- Dispense rate 5-50 LPM
- Dispense should be continuous
- The material is concrete paste
- Solid content is up to 4 mm
- delivery length is 5-6 meters
- bends - 3
- Hose dia 38 mm
- 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.
The flow often stops, for which we had to reverse the motor few rotations and then run forward. But this operation is not acceptable.
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??