The main reasons for the slow action of the regulating valve are:
Pneumatic film actuators in the diaphragm damage leakage;
O-ring leakage in the actuator;
The valve body is blocked by debris;
Teflon packing disintegrated hardening or graphite-asbestos packing lubricating oil dry;
Packing pressure is too tight, the friction resistance increases;
Because the stem is not straight, friction resistance increases.
Solution:
Replace broken diaphragm;
Replace the O-ring;
Tidy up the debris in the valve body;
Replacement packing;
Adjust the packing gland properly;
Replace the stem.
