What does the requirement regarding liquefied petroleum gas transfer pumps in the foreign LPG standard NFPA58 mean?
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I have been reviewing foreign LPG regulations recently, and these regulations contain requirements regarding transfer pumps. As shown in the image below, the red box indicates that when the maximum pressure difference of the pump exceeds 125 psi, a \"bypass valve\" must be added. How should this statement be understood? Additionally, where in the pump should the bypass valve be installed according to the regulations?
As specified in the standards, if the maximum pressure difference of the pump exceeds 125 psi, a bypass valve needs to be added. This means that when the pressure becomes too high, the bypass valve can open automatically to allow some of the liquid to flow back to the pump inlet or storage tank, thereby reducing the system pressure and protecting the safety of the pump and the system. A bypass valve is usually installed on the pump’s outlet pipe and connected to the pump’s inlet pipe or the low-pressure area. This ensures that when the outlet pressure of the pump exceeds the set value, the bypass valve can direct the liquid back to the pump’s inlet or back to the storage tank, thereby preventing excessive pressure from causing damage to the pump and piping system. .
Thank you for your answer! Thank you so much!
You’re welcome! I’m glad I could help you! If you have any other questions, feel free to ask. Wish you success in your work! .
The pressure difference is too high, making it difficult to start the pump; a bypass valve is installed to protect the pump
May I ask: Is the structure and principle of the bypass valve exactly the same as those of the pressure relief valve? Is it for single-use only, or can it be recalibrated and used again after a safety valve releases pressure?
This valve is called a safety return valve, and the pressure difference can be adjusted during calibration.