Operating Procedures for Process Loading and Unloading Pumps

It’s easier for everyone to read if you just post it directly! Operating Procedures for Process Loading and Unloading Pumps I. Preparations before startup 1. Check the liquid level and pressure of the corresponding operating spherical tank and/or tank truck. 2. Check whether the valves and other accessories of the relevant process pipelines are in good condition, and open all valves on the pipelines except those at the pump inlet and outlet. 3. Check whether the lubrication, connections, and fastenings are in good condition. 4. Open the pump inlet valve, close the outlet valve, and notify power to be supplied. II. Starting up 1. Move the on-site operation switch of the pump to the “On” position. 2. Open the pump outlet valve once the pump speed is stable. 3. Check the liquid pump for any abnormal noises, as well as issues such as air leakage, fluid leakage, or overheating; if any abnormalities are detected, stop the machine immediately for inspection. 4. Monitor the current; the pump must not operate under overload. 5. The outlet pressure difference of the pump should not exceed 1.2 MPa; if it does, the pump must be stopped immediately for inspection. 6. The inlet valve is fully open and cannot be used to regulate flow. Pumps should not be operated continuously for more than 3 minutes in the absence of loading/unloading by vehicles/boats or tank transfer operations. 7. Once the pump is running properly, the operator must check its operation every half hour and keep a record of it. 8. When starting the process loading and unloading pump, air entrapment may occur (especially when the temperature is high at noon); in such cases, the pump should not be operated for an extended period of time (not more than 3 minutes). This issue can be resolved by venting air from the pump’s outlet. To avoid this situation, the pump can be started at intervals according to the production plan and operated for 10 minutes to prevent the formation of air pockets. III. Parking 1. Turn the on-site control switch to the “off” position, and the pump will stop. 2. Close the inlet and outlet valves. Restore the process as required. 3. Notify of the power outage and clear the site. 4. Special note: If there is no safety valve between the pump and its inlet and outlet valves, at least one of the inlet and outlet valves should be kept in the open position.

This procedure should state that it is applicable only to centrifugal pumps

Agree with what was said above; generally, centrifugal pumps are used for unloading

Is there a problem with the third point mentioned by the poster? Why close the pump first and then the outlet valve? Won’t this have an impact on the pump? If the material flows back, it will cause problems, and it may also lead to water hammer

Thank you all for participating in the discussion. This operating procedure has been used in previous gas storage facilities for nearly a decade, with no significant changes made in each revision. In actual work, perhaps some problems were also noticed by others, but due to a lack of discussion, they remained unclear and unaddressed. If this is the case for those who formulate and revise various regulations, it is only inevitable that workers will make mistakes while operating. Here I agree with what was said on floor 5. As for the reason, I think the explanation provided by Haiyou hldll44302 in the discussion on \"why the outlet valve must be closed slowly when shutting down a centrifugal pump\" is quite reasonable: \"First, it’s necessary to understand what is meant by ‘closing first’ and ‘slowly’. Closing the outlet valve first when stopping a centrifugal pump serves to prevent the motor coils from overheating. Additionally, in the past, large motors in substations used oil-filled switches; shutting down the pump under load would generate arcs, which could degrade the oil inside the switches.\" The switches used now are vacuum switches, so it should have little impact. In abnormal situations, the pump can be stopped first, followed by closing the outlet valve. Flow rate and power are proportional to each other; when the outlet valve is closed, the motor’s power is at its lowest, meaning the load is minimal. Therefore, to stop a centrifugal pump, it is necessary to close the outlet valve first. As for closing the valve slowly, it is to prevent water hammer; in fact, the impact of this is not that great. When you stop the pump, it causes a significant shock to the entire piping system, and that is where the greatest impact occurs. ”

Not bad; the information upstairs is excellent, with very thorough explanations