English
中文简体Zero leakage means that the sealing performance of the valve is good, and the leakage of the brass beer valve is close to zero under the allowable pressure difference. The size of the leakage of the valve is determined by the sealing of the valve.
The allowable leakage of the valve:
The user should decide on the maximum operating leakage, or determine the degree of sealing required over the desired valve life before trim replacement repairs. This can be used as a basis for selecting the appropriate valve type to meet these conditions. Some valves remain in the field for long periods of time with factory-tested leaks. Others, on the other hand, scratch quickly or suffer minor damage due to repeated closing or corrosion, resulting in higher leakage in normal use.
Stem packing material:
The PTFE packing has low friction resistance, small valve variation, and extremely tight sealing. Graphite asbestos packing is suitable for higher use temperature. When the valve is used in a poor environment, the leakage of graphite asbestos packing is much higher than that of PTFE packing. When the graphite asbestos packing is close to the same smoke density as that of the PTFE packing, the deterioration will be very large, and the valve operation will be unstable.
Bellows stem seal:
Bellows seals are used where hazardous fluids are contained or where the fluid will lose the normally used packing material. They are often used in radioactive or vacuum applications to prevent air contamination in pipelines. Bellows seals are expensive, have limited travel, and require higher actuator thrust to overcome the elasticity of the bellows. This sealing method should be avoided in non-critical situations. The cyclically varying service life of the bellows seal depends on the full or partial throttle stroke.
