Problem with the check valve in the pump outlet pipeline
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Article 4.3.9 of GB 50160-92 Code for Fire Protection Design of Petrochemical Enterprises (revised in 1999): Check valves shall be installed on the outlet pipelines of combustible gas compressors and centrifugal combustible liquid pumps in cases where power failure, steam interruption, or abnormal operation may lead to backflow of the medium and thus cause accidents. Under normal circumstances, a backup pump is considered to prevent accidents caused by reverse rotation of the impeller when the head is high. GB 50160-2008【2019 revised version】Code for Fire Protection Design of Petrochemical Enterprises introduces new requirements: 7.2.11 Centrifugal combustible gas compressors and combustible liquid pumps shall be equipped with check valves on their outlet pipes. Is it necessary to install a check valve no matter what?
It’s still necessary to analyze specific situations on a case-by-case basis
This post was last edited by CHANGBAISHI on 2020-11-27 08:43. It would be best to take another close look at the details of the “rules” before proceeding with further discussion. It can be said that, literally speaking, there is nothing inappropriate about it. It is recommended to share a schematic diagram of the actual on-site process for discussion, as this will make it more intuitive. However, some pipeline pumps do not take into account the impact of backflow, and some are not equipped with such a mechanism. The key point is that this situation does occur as well – the submersible pump in my home’s aquarium doesn’t need to be installed. Perhaps it’s because the system is simple and has a small capacity, and reverse rotation or other issues won’t cause any negative effects, so there’s no need to install valves to create resistance.
The preparation notes for the 2019 revised version state that backflow may cause fires. HG20570.18-95 states that for leaf pumps (commonly centrifugal pumps), a backflow of liquid can lead to various situations; therefore, a check valve should be installed on the pump outlet pipe ； a. The liquid temperature rises, being more than 90°C higher than the normal transfer temperature. b. The combined temperature and pressure of the output fluid exceed the design conditions of the pump casing. c. The impeller may be damaged due to reversal. d. Various variations that are not permissible in the process operation. I think this is more reasonable; the common situation corresponding to option d is backflow, which may lead to a fire.
For generally flammable and explosive materials as well as those that are toxic, check valves should be installed to prevent backflow
The main considerations are backpressure and mixing of media; if these two issues do not exist, there is no need to install a check valve.
Although check valves do not provide 100% sealing, they are still an effective means of preventing backflow from the compressor, so there is no need to worry about it.
This post was last edited by CHANGBAISHI on 2020-11-30 09:06. I’m not sure what your specific question is; it seems to you that only \"fires\" are a concern, but there are also many processes other than fires that are not allowed. If discussing word games, it is advisable to get more involved and learn more about the processes as well as the requirements for installing check valves. This cannot be clarified just by what seems reasonable to an individual; it’s simply a matter of having a good understanding, though perhaps not a comprehensive one, to be honest.
It is quite clear that centrifugal combustible gas compressors and combustible liquid pumps should be equipped with check valves, as explained in clause 7.2.11, in order to prevent backflow in the event of an accident
The properties of the materials also need to be taken into account. The situation you described is now a special case; under normal conditions, the relevant specifications should be followed
The metaphor is very specific! ! ! ! !