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Troubleshooting Pressure Issues in Reciprocating Compressor Lubrication Systems
Release date:
2026-04-06
The stable operation of the reciprocating compressor’s lubrication oil control system is critical to the enterprise’s normal production. Moreover, the compressor’s dual-motor interlock system helps reduce the likelihood of bearing seizure caused by insufficient lubrication, thereby ensuring the safe and stable operation of the unit.
The stable operation of the reciprocating compressor’s lubrication oil control system is critical to the enterprise’s normal production. Moreover, the compressor’s dual-motor interlock system helps reduce the likelihood of bearing seizure caused by insufficient lubrication, thereby ensuring the safe and stable operation of the unit.
I. Causes of Low Lubricating Oil Pressure in Reciprocating Compressors
The reciprocating compressor lubrication oil system, also known as the oil station, ensures that, during operation, a specified oil pressure is delivered to all lubrication points. This maintains optimal cooling and lubrication conditions for the compressor’s moving parts, reduces wear, extends the equipment’s service life, and lowers the likelihood of failures. The lubrication system is driven by an electric motor and includes auxiliary gear oil pumps, main shaft gear oil pumps, an oil cooler, and a plunger-type oil injector. The schematic circulation path of the lubrication oil circuit is as follows:
Path 1: Crankcase → Crankcase coarse oil filter housing → Auxiliary gear oil pump → Oil cooler → Main shaft gear oil pump → Fine oil filter → Crankshaft → Lubrication station
Path 2: Crankcase → Crankcase coarse oil filter housing → Oil cooler → Main shaft gear oil pump → Fine oil filter → Crankshaft → Lubrication points
Possible causes of low oil pressure in the lubrication system of a reciprocating compressor include an inaccurate oil pressure gauge, a low oil level in the oil tank, excessive clearance due to wear of the crankshaft‑connecting rod bearings, substandard lubricant quality, excessive clearance between the crosshead and guide ways, blockages in the oil cooler or oil lines, and air entrapped in the oil piping, as detailed below:
(1) The bent pipe structure is unreasonable.
The lubricating oil in the tank was drained, and upon opening the tank’s access port, it was observed that the oil pump’s suction line bends downward within the tank. This configuration is a common design for most oil‑station systems equipped with an oil tank; however, its drawback is that, as return oil passes through this bend into the tank, entrained air—present in the return flow—can separate out and accumulate at the bend. Once this air reaches the auxiliary oil pump’s inlet, it cannot escape, preventing the system from building adequate pressure. Consequently, when the auxiliary oil pump is automatically started, the odor emanating from the pump’s suction side inhibits the establishment of proper system oil pressure, causing the unit to trip and shut down because the main lubrication‑oil line pressure falls below the trip‑out threshold.
(2) Auxiliary oil pump inlet filter
An increasing diameter is present between the inlet filter of the auxiliary oil pump and the filter body itself. With smaller diameters at both ends and a larger diameter in the middle, gas can accumulate in the central section, preventing its venting. Once the auxiliary oil pump is started, this trapped gas enters the lubrication oil system, hindering the timely establishment of system pressure and potentially triggering a cascade shutdown due to low oil pressure. Due to the manufacturing lead time for the filter, this maintenance did not involve replacing it; however, a vent valve was installed at the top of the filter. After performing a normal flush, the vent valve was opened to vent the accumulated gas, thereby ensuring that gas is discharged from the upper portion of the filter. By periodically venting through the valve, the entrapped gas can be effectively removed.
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