First, it's essential to understand the working principle of air compressor thermostatic valves. In air compressor cooling systems, self-operated three-way thermostatic valves are primarily used. Taking the Sullair LS-205-150LWCKT air compressor unit as an example, the working principle of the air compressor's cooling and lubrication system is familiar to anyone knowledgeable about compressors.
The lubricating oil and compressed air mixture flows from the compressor to the separator for separation. Under pressure differential, the lubricating oil flows back to the compressor via the thermostatic valve. When the oil temperature is below the set temperature of 77°C, the thermostatic valve closes, the oil bypasses, and the oil directly enters the compressor circulation through the oil filter. Due to absorbing the heat generated during compression, the oil temperature gradually rises. When the oil temperature exceeds 77°C, the thermostatic valve begins to open, some oil flows into the cooler for cooling, and then enters the compressor through the oil filter. Fault identification: When the exhaust temperature exceeds 113°C, the ambient temperature is only around 20°C, and the cooling water temperature and inlet/outlet water pressure are normal. At this point, the oil temperature in the pipe from the thermostatic valve to the cooler feels low to the touch. However, the oil temperature in the pipe bypassing the thermostatic valve and entering the compressor is extremely high, making it untouchable. This indicates that the thermostatic valve is not open, and the lubricating oil, without cooling, continues to rise in temperature, leading to automatic shutdown.
Therefore, the thermostatic valve is faulty. In this case, the thermostatic valve or valve core needs to be replaced promptly to resolve the problem.