Selection of pump inlet bottom valve
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The project requires two centrifugal pumps with a flow rate of 6 m3/h and a head of 60 m; the centrifugal pumps have been selected and ordered. It has been found that this pump does not have self-priming capability. The pump manufacturer recommends installing a flanged bottom valve on the pump’s inlet pipeline, as the medium used by the pump is a mixture of water and tar (which can be considered as pure tar). Upon consulting the manufacturer of bottom valves, it was stated that such valves are only suitable for applications where the medium is water; they cannot be used when the medium is tar. I would like to ask if anyone knows whether it is feasible to use a bottom valve in my situation (Note: The pump inlet pipe is fixed to the horizontal tank, extending into the equipment near its bottom; a bottom valve needs to be installed on the pipe inside the equipment.)
This post was last edited by zhangqi1234 on 2018-10-17 at 14:38. For a mixture of tar (which can be treated as pure tar), if its viscosity is high, it can be challenging to use centrifugal pumps. The bottom valve is meant to deceive the enemy anyway; what about adding a self-priming tank as well?
If the viscosity is too high, it is not recommended to use a centrifugal pump; instead, a positive-displacement pump should be used. It is also best not to draw liquid in directly, but rather to have openings on the side or bottom of the tank from which the liquid can be poured in. This type of bottom valve is used in tar and tends to stick shut, making it difficult to open.
If the viscosity is too high, it is not recommended to use a centrifugal pump
I agree with the opinions of the experts mentioned above. High viscosity can cause fatal damage to both the impeller and the mechanical seal. If the viscosity is not high, considering the installation of an external flushing system would be advisable; fresh fluid should be used as the flushing medium, and the pump should be cleaned of any residual material using this fresh external fluid before and after it is started up. As for the foot valve, it might be appropriate to install a priming tank at the pump inlet
OP, just how high is the viscosity?
I suddenly realized that it might not be the valve of the pump that’s leaking, and that the wrong pump was chosen – it’s a bit embarrassing
Tar centrifugal pumps with high viscosity alone are not useful; they stop working as soon as they try to draw in liquid
The viscosity is too high; it’s likely that the pump won’t be able to draw it up