Why does the oil pump of a nitrogen compressor often switch automatically?

Pump A and Pump B are frequently switched back and forth, and it is necessary to keep turning the knob to set \"A in use with B as backup, or B in use with A as backup\", which is very troublesome.

This question is closely related to logic. The current conditions are unclear

Based on our equipment and my opinion: 1. The process engineers should check whether large fluctuations in the outlet pressures of pumps A and B are causing the startups. 2. They should also check whether the automatic control valves at the outlets of pumps A and B are operating unstably. 3. The instrumentation team should examine the pressure transmitters used for the automatic startup of the auxiliary pumps. 4. If oil-sealed pumps are involved, it is necessary to check whether changes in the level of the seal oil in the reservoir are causing startups. 5. Changes in the pressure of the control oil can also lead to startups

1 Is the frequent automatic switching of the lubrication oil pump in a compressor unit an indication of high automation? 2 Generally, in logical design, when the oil pressure drops due to pump (A), the backup pump (B) is activated, but pump A does not stop automatically once pump B starts operating. Logically, it is also not designed to automatically shut down pump A in order to avoid excessively low lubricating oil pressure. 3 As for the phenomenon observed in the original poster’s friend, the most likely cause is an electrical issue, while the logical control system performs excellently: in the event of an electrical problem such as a failure in the power supply for pump A, pump B will start automatically once the oil pressure drops ； Or vice versa. The poster’s friend might as well give it a try and see whether the pump stops first before the backup pump is started, or whether the backup pump starts first before the main pump stops – there are differences in the reasons for these two scenarios

1. The logic for starting the backup pump is incorrect. 2. There is a problem with the oil pressure gauge, which shows a lower value than the actual pressure. 3. The capacity of the oil pump has decreased, or the circulation volume in the oil system is too high

The pump outlet pressure indication is inaccurate and falls below the lower limit of the process specifications (regardless of whether the actual value is higher or lower than this limit), which results in the conditions for automatic startup of Pump B being met; therefore, the instruments and electrical systems should be thoroughly inspected.

Check whether the oil filter is functioning properly

It should be checked from the following aspects: 1. Whether there was indeed a fluctuation in the oil system that caused the auxiliary pump to start automatically; this can be determined by examining the historical data. If there was indeed a fluctuation in oil pressure, then the possible reasons for such fluctuations are as follows: the pressure setting for automatic startup of the auxiliary pump might be too high； Self-regulating valves or safety issues ； The oil temperature fluctuates too much ； There is a problem with the oil pump itself ； Filter issues, etc. 2. Instrument issues 3. Electrical issues

The backup pump was started first, and then the pump that was in operation was shut down. There should be no problem with the oil pump; the other three compressors have not experienced the same issue. It seems that the oil pressure of that particular compressor doesn’t fluctuate much

Thank you all for your advice. Then, what are the differences in the reasons behind stopping the main pump first and then starting the backup pump, as compared to starting the backup pump first and then stopping the main pump?

Does anyone have the operating procedures for starting the compressor oil pump and switching between the main and auxiliary oil pumps? Thank you in advance

Set the in-use pump to manual mode and the standby pump to automatic mode； It can be switched regularly in the future.