09/06/2023
Check out this informative post from our friends at BAUER KOMPRESSOREN describing how a pressure retention valve works!
How a pressure retention valve works
Although a pressure retention valve is one of the most important components in the system, its role is unjustly downplayed. Yet no compressor could operate without it! In this article, we examine why that is, and get to know the task and function of the valve in more detail. The pressure retention is located downstream of the final separator and the filter system. Its job is to maintain a predefined minimum pressure in the system; as a rule of thumb, that level is around 60 per cent of final pressure. In a system with, say, 300 bar pressure, the pressure retention valve would thus be set at 180 bar. The valve remains closed when the compressor starts up, and only opens when the pre-set pressure is reached. This closed valve prevents the compressor from compressing into a completely depressurized system for too long where there is no counterpressure in the form of a pressure vessel to be filled (e.g. an empty scuba tank or storage cylinder) or downstream piping system. The pressure retention valve only opens once the pre-set minimum pressure has been reached. This is necessary for various reasons. One is the free piston that can be found in the final stage of all BAUER high-pressure compressor blocks. As it is unconnected to the crankshaft, it requires an appropriate level of counterpressure in order to function. The pressure retention valve allows pressure to build rapidly in the relatively low-volume interior of the compressor. This enables the free piston to operate smoothly. But the valve has a further important function for the air purification system. Without the pressure retention valve, the cartridge filter system would undergo a sudden and extreme loss of pressure upon system shutdown, draining or venting of the filling panel piping, followed by a rise in pressure. This process would expose the filter housing – which is made from special aluminium alloy – to high cyclical loads that would result in premature fatiguing of the material over time. The higher the pressure difference, the more extensive the impact of this process. The pressure retention valve works in tandem with a check valve to minimize loss of pressure, thus significantly increasing the service life of the filter housing.
