Does a shielded pump require a check valve to be installed on its outlet pipe?
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Article 7.2.11 of the Code for Fire Protection Design of Petrochemical Enterprises GB50160-2008 stipulates that a check valve shall be installed on the outlet pipeline of centrifugal flammable liquid pumps in cases where power failure, steam interruption, or abnormal operation may lead to backflow of the medium and thus cause an accident. Question: Does a canned pump require a check valve to be installed on its outlet pipe?
All the centrifugal pumps I’ve seen have check valves installed on their outlet pipes
A shielded pump is actually a type of centrifugal pump, only it has better sealing performance. As for whether to install a check valve at the outlet, it depends on the properties of the medium; one is necessary for flammable liquids
Centrifugal pumps almost always have them; besides, shielded pumps are so expensive – it would be a shame to damage them
A shielded pump is also a type of centrifugal pump, and its working principle is the same: it relies on the rotation of the impeller to generate the force needed for transportation, so it also needs a device to prevent backflow. All the shielded pumps in our factory are equipped with check valves.
Yes, a shielded pump is a type of centrifugal pump, so of course it needs to be added. And I think it should be added not just for media, but for any shielded pump. For example, in a pump setup with one main pump and one standby pump, if no check valve is used and the valve is closed tightly, it can easily cause the liquid in the standby pump to flow in the reverse direction, reducing the efficiency of the pump in use. Moreover, backflow of liquid poses a safety risk of causing the impeller to come loose; one can ask the maintenance team about this, or observe it when there’s a chance to disassemble the impeller for inspection. The impeller has a specific orientation, and reversing its direction can cause the bolts to loosen and fall off.