Why should a gas-operated type be chosen for the compressor inlet control valve?

The choice between air-open and air-close valves is based on three main factors: 1) keeping the process equipment in a safe state in the event of an accident; 2) minimizing energy and kinetic energy consumption during accidents to ensure product quality; 3) considering the properties of the medium. I believe that the valve at the compressor inlet should be of the air-close type, meaning it closes when there is gas present and opens when there is no gas. Since the compressor is used to compress the medium, in the event of an accident or a failure in the gas supply, the valve opening ensures that the compressor continues to operate. If there is no medium, the compressor running idle can damage its bearings or blades, and it may also cause the medium to flow back, damaging the impeller and reducing the compressor’s efficiency. Moreover, if dangerous media are involved, this could lead to leaks, posing a serious threat to the safety of the equipment and personnel. Therefore, an air-close valve should be chosen

The choice between air-open and air-close types is primarily aimed at ensuring that no serious safety accidents occur in the plant’s operations during extreme accident conditions. The inlet valve should be of the air-actuated type, meaning that when the instrument air supply is interrupted, the valve remains in the fully open position. At this time, regardless of whether the compressor is operating properly or not, its speed will remain high for a certain period; it is therefore necessary to ensure that the inlet does not become vacuum, as this could damage the equipment. Some compressors can keep operating for a while even if the instrument air is interrupted, which makes this even more necessary.

A pneumatic-operated valve means that in the event of a failure in the instrument air supply, the valve opens automatically, thereby ensuring that the unit has as much flow as possible to operate. Prevent damage to the equipment.

To prevent the compressor inlet from experiencing a lack of gas in the event of an instrument air interruption, which could lead to negative pressure in the compressor.

The choice between using a valve that opens under pressure or one that closes under pressure should be made from the perspective of the production process. If the valve is operated by air and suddenly fails to open, causing it to close abruptly, what extent of damage will that cause to the compressor? Especially in centrifugal compressors, there is also a surge condition; not only must the gas shut-off valve be used at the compressor inlet, but the surge preventer valve as well must be of the gas-shut-off type.