Common Faults and Prevention of Air Compressor Suction Valves

The air compressor suction valve is an accessory capable of stabilizing pipeline pressure without additional vent lines. During daily operation of air compressor suction valves, 

various faults frequently occur. What are the root causes of these faults, and how can they be prevented? This article analyzes frequent suction valve faults, 

aiming to identify fault causes and implement corresponding preventive measures promptly to reduce failure rates and ensure safe and stable operation of the unit.

I. Analysis Based on Maintenance Records

Air valves suffer relatively high failure rates. Dismantling and inspection reveal large amounts of liquid accumulated in the air passages, 

valve seats and valve chambers, leading to frequent air valve replacement.

Air valve leakage is mainly caused by mechanical damage, excessive wear of air valve components and medium corrosion. Valve plates and springs are the most vulnerable parts. 

Air valve leakage reduces the delivery capacity of the air compressor and disturbs interstage pressure and temperature. Air valve leakage falls into two categories: external leakage and internal leakage.

1. External Leakage

External leakage of suction and discharge valves arises when bolts connecting valve covers and cylinders are not tightened properly or tightened askew. Besides, 

damaged, failed or misaligned gaskets can also trigger external leakage.

Although external leakage exerts limited impact on air compressor displacement, propane is flammable, explosive and toxic, which poses severe hazards to operators’ health and the surrounding environment. 

Such defects are generally attributed to inadequate skills or carelessness of maintenance personnel and poor air valve installation quality. Once external leakage emerges after trial operation, 

the unit has to be shut down again for pressure relief and medium replacement before rework, resulting in economic losses. In most cases, external leakage can be avoided during air valve installation.

2. Internal Leakage

Internal leakage of air valves has two main causes. On one hand, damaged, failed or improperly fitted sealing gaskets between air valves and cylinders lead to leakage between air chambers and cylinders and insufficient displacement. 

On the other hand, valve plates fail to seat fully, resulting in leakage.

Reasons preventing valve plates from proper seating are listed as follows:
Poor contact between valve seat and valve plate causing air leakage;
Metal fragments or other foreign matters trapped between valve seat and valve plate leading to incomplete closure and air leakage;
Improper design and selection of suction valve springs: excessively strong springs delay valve opening during suction, while overly weak springs cause delayed closure at the end of suction stroke;
Wear of valve seat and valve plate resulting in poor sealing and air leakage; insufficient suction lift height accelerates gas flow velocity and increases flow resistance;
Jammed or tilted springs preventing tight closure of valve plates;
Fractured suction valve springs lead to incomplete and delayed closure during compression.
II. Air Valve Leakage Caused by Fatigue Failure of Valve Plates
Valve plates are sheet-shaped components that alternately open and close the passages on valve seats.
Research indicates that air valve damage originates from two primary loads acting on valve plates during operation:

Uniformly distributed load generated by pressure difference on both sides of the valve plate. This load fluctuates periodically along with cyclic pressure variation inside the cylinder, 

forming alternating cyclic loads that induce bending fatigue failure and circumferential cracks on valve plates.

Impact load produced when valve plates collide with lift limiters and valve seats. Continuous operation of the air compressor repeats such collisions constantly, 

triggering bending deformation of valve plates and radial fractures initiating from the outer edge. The impact force is related to the mass and moving speed of valve plates.