The dynamic stability of the pneumatic valve safely

when the pressure protection system, to produce an effect on the sensitive element of the additional force, making the element and opened the gap in security pneumatic valve passage, medium through the gap. Safety pneumatic valve discharge capacity and service life of the parts, related to the dynamic stability of the pneumatic valve work safety. The oscillation of the pneumatic valve can make the security channel cross-sectional area of pneumatic valve and discharge capacity decreases, and the pneumatic valve with pneumatic seat and open height limiter collision might damage the security of the pneumatic valve sealing surface and other parts. Two segments of the rev safety type pneumatic valve is the most easy generation pneumatic disc.
safety pneumatic valve dynamic instability is mainly caused by the following reasons: security into safe pneumatic valve pneumatic valve discharge capacity of the medium flow, spring stiffness is too large, the pneumatic valve opens on the pneumatic disc cavity in the back pressure and dynamic interference from the outside.
a. Discharge capacity influence
if you develop any of the following, the safety of pneumatic valve discharge may occur ability over into the medium flow pneumatic valves:
. Was elected with the safety of the pneumatic valve channel cross-sectional area exceeds the cross-sectional area of the calculations required:
. When security pneumatic valve installed on the emergency delivery system with the change:
. When the inlet piping cross-sectional area is not enough, and so on.
2. Spring stiffness
the spring stiffness is too big can also be the cause of the pneumatic disc oscillation. Full rev type safety pneumatic valve can achieve full open emissions depends on the medium to long-term, but spring stiffness is too large, the force can family spring force can't make it to set the opening height, so the security of pneumatic valve is also unable to achieve full amount of emissions, as soon as it will lead to safer pneumatic valve open return, form oscillation. If small stiffness, the security of pneumatic valve under low pressure to seat back.
in order to eliminate this kind of phenomenon, should be installed according to the design of the spring, or when the design should be more than the actual sets of spring experiment, through the test to determine the most appropriate spring.
3. System back pressure influence:
with similar impact of spring stiffness is too large, pneumatic valve body cavity above in safety pneumatic valve open when the back pressure may also cause the pneumatic disc oscillation. In order to avoid to produce a large back pressure, pneumatic valve to open security is to use an opening in a pneumatic valve pneumatic valve body cavity and the atmosphere above the connected. For closed-end security pneumatic valve, pneumatic valve body cavity and above pneumatic valve body can be exported or export branch pipe connected, using the pneumatic valve at the top of the suction effect to reduce the pressure.