Does the auxiliary oil pump not need to be turned on when a reciprocating compressor is running?

Could you explain in detail? In the reciprocating compressors I’ve worked with before, the auxiliary oil pumps had to be running, and there were two of them; in addition, there was a low oil pressure automatic start interlock

The auxiliary oil pump first creates the oil pressure; once it starts operating, the crankshaft’s built-in pump takes over, with the auxiliary pump being activated only when the oil pressure is insufficient

It means there is a device on the crankshaft that functions in the same way as a pump

Check your equipment: if there are two oil pumps, they should be shaftless pumps, which you are familiar with. If there is only one pump, then it is likely to be a shafted pump, meaning that one oil pump is driven by a main shaft. Since lubrication is required during startup, the auxiliary pump is removed; once the main oil pump starts operating, the start/stop of the auxiliary pump is determined based on the oil pressure

It’s a pump, either a screw pump or a gear pump

Currently, there are generally two methods for the lubrication system of reciprocating machines. The first type is a dual electric pump; there is also a configuration with one shaft-mounted pump and one electric pump. The operation methods are different. In units equipped with dual electric pumps, one electric pump is started first at startup to generate oil pressure; only after it stabilizes can the other pump be turned on. Remember to set the other electric pump in automatic mode, so that in case there are problems with the operating pump and the oil pressure drops, the backup pump can start automatically. Before starting the unit equipped with a pump with a shaft coupling, start the electric pump first; once the oil pressure reaches the required level, then start the unit. At this point, the lubrication system operates with two pumps, resulting in a slightly higher oil pressure. Generally, when the oil pressure reaches 0.4 MPa, the electric pump is stopped manually. Then set the electric pump to automatic mode. During the process of stopping the pump, be careful of the low oil pressure interlock, as the self-acting oil pressure control valve has a delay in response, which may lead to shutdown due to low oil pressure. We usually temporarily disable the oil pressure interlock, and re-enable it once the situation stabilizes.

Thank you. Is this shaft-mounted pump installed on the crankshaft?

To be precise, it’s not on the crankshaft. At the end of the crankshaft (the non-driving end), a large gear drives a small gear to operate the shaft-end pump.