Why is a check valve required for parallel-connected air compressors?
In industrial production, to meet substantial air‑demand requirements, two or more compressors are typically operated in parallel. In such piping configurations,Installing a check valve is essential.The primary function of a check valve (also known as a one-way valve) is to prevent backflow of gaseous or liquid media. When two air compressors are connected in parallel, if one unit experiences a malfunction, reaches its pressure limit, or undergoes a scheduled shutdown while the other remains operational, the high-pressure compressed air produced by the running unit can easily flow backward through the common piping and enter the stopped compressor.
Potential Risks of Not Installing a Check Valve
If a check valve is omitted in a parallel piping system, it may give rise to a series of serious equipment problems:
- Host reversal damageHigh-pressure gas backflow can force the compressor’s main unit, which is in a shutdown state, to rotate in reverse, potentially causing severe wear—or even outright failure—of its internal rotor, bearings, and other critical components.
- Motor damageBackflow-induced reversal not only affects the main unit but can also subject the drive motor to impact, thereby shortening its service life.
- Lubricant leakageBackflowing high-pressure gas can damage the oil–gas separation system inside a shut-down air compressor, causing lubricating oil to be forced into the compressed air pipeline and contaminating downstream air-using equipment.
- System pressure fluctuationsGas backflow can cause severe pressure fluctuations throughout the compressed air system, compromising the stability of process air supply.
Recommendations for the Proper Installation and Selection of Check Valves
To ensure the safe and stable operation of a parallel system, the following points should be observed when installing check valves:
- Installation locationCheck valves shall be installed on the pipeline segment at the connection between the discharge port of each air compressor and the parallel header, as close as possible to the compressor’s discharge end, to minimize the volume of backflow.
- Flow confirmationDuring installation, carefully verify the arrow marking on the valve body to ensure that the arrow points in the same direction as the actual flow of compressed air; installing it backward will result in complete blockage of the pipeline.
- Selection and matchingThe check valve should be selected with appropriate specifications and pressure ratings based on the air compressor’s displacement, operating pressure, and pipe diameter, to avoid unnecessary pressure losses caused by an undersized valve.
- Regular maintenanceThe internal seals of the check valve may wear or become stuck after prolonged use. It is recommended to include them in your routine maintenance schedule and periodically inspect their sealing performance to ensure smooth and reliable operation.
Properly configuring and correctly installing check valves is a fundamental step in ensuring the safe and efficient operation of a parallel‑connected system with multiple air compressors. During the pipeline design and construction phases, they must be implemented as standard equipment without exception.