Pump inlet and outlet venting issues
Thread Content
In previous design projects, a DN20 or 25 pipe was used as a vent on the inlet filter of the centrifugal pump. But recently I encountered a case where vents were installed at both the inlet and outlet of the pump. What is the purpose of doing this? What are the benefits? Thank you! Illustration: http://photo.163.com/photo/zouyangyong/?u=zouyangyong#m=2&ai=128424442&pi=5691226122&p=1
This post was last edited by spc1212 on 2010-1-18 21:29. Centrifugal pumps generally have a cleaning valve installed at the inlet and a vent valve at the outlet; the same is true in your case as well
By the drain valve you mentioned, do you mean one used to release liquids? When installing the piping, we connect it from above the filter.
According to the diagram, this is the piping design for a standard pump: the inlet is used for drainage, and the outlet is used for venting. When the pump needs to be repaired, it is drained through the inlet, while when the pump is started up, it is necessary to ensure that the pump is filled with liquid; in that case, air is expelled through the outlet.
I don’t think it’s necessary to add a vent pipe at the pump outlet, because there should already be a vent pipe on the outlet pressure gauge. Should the pump inlet flanges also be level with each other?
Personally, I think the vent valve before the pump is used to release the material remaining in the pump during shutdown for maintenance, while the vent valve behind the pump is used to exhaust air when the pump is started
Is the pump outlet filter a basket filter? The upper part of the basket filter is higher than the pipeline; after cleaning the filter screen, air enters, and it is necessary to exhaust the air from the filter before opening the outlet valve
The vent valve of the pump’s feed valve is used to release air when the pump is started, while the vent valve of the pump’s outlet valve is used for washing or purging with air during pump shutdown and maintenance, in order to clean out the material inside the pump!
The outlet backflow is used for venting the pump body.
In general design: the inlet of the centrifugal pump is of eccentric reduced-diameter type (flat on top), with a drain pipe installed at the lowest point at the bottom； The outlet of the centrifugal pump is of concentric reducing design; a drain is provided at a position higher than the pump, and the pump is filled with fluid and its air is removed before it is started up.
For the design vent at the highest point of the pipeline, is it necessary to use a valve? Can flanges and blind plates be used instead? There’s another issue: there is no straight section of pipe at the highest point of my piping outlet. What should I do? Is it better to locate this outlet on a elbow or on a flange?