Azbil AMT User Manual

Azbil Corporation
Model: AMT, HDT - CV3000 Series Control Valves
53
10. TROUBLESHOOTING
This section covers the symptoms, causes and remedies of most probable types of
troubles. Parts may be required to be replaced depending on the type of trouble.
For further troubles, please order your Azbil Corporation agent for repair.
Table 10-1 Troubleshooting
Symptom Cause and Remedy
Unstable valve operation
• Valve position hunting occurs
when almost fully closed.
• Cv value is too large. Reduce Cv value.
• For a single scat Valve, the valve is Installed in the reverse flow
direction.
• Air supply pressure is unstable. • Large air consuming equipment is hooked up to the same air supply
line. Check that the air supply capacity piping capacity and restriction
capacity are appropriate.
• Supply air pressure regulator is inadequate or not operating properly.
• Signal pressure is unstable. • Controller is not properly tuned. Property tune the controller
(properly set the proportional band and other parameters).
• Check that the controller output does not change abnormally.
• Valve position hunting occurs even
when signal pressure is stable.
• Hunting of output of positioner itself. Check and repair or replace the
positioner.
• Being affected by pressure change of process fluid as power of the
actuator is insufficient. Replace the actuator with a Iarger one.
Vibration of valve
• Valve vibrates (generate noise) at
any position of valve plug.
• Piping is vibrating. Securely fix the piping.
• Check for other sources of vibration. Worn valve plug or guides.
Check the parts and replace them as required.
• Valve vibrates (generate noise)
only when valve plug is set at a
certain position.
• Check for change in process fluid flow conditions
(change in restriction orifice, Cv value, etc.)
• Check for change in plug configuration
(change in flow control characteristics.)
Sluggish valve operation or
inoperative Valve
• Air leak from piping
• Air leak from actuator
• Foreign matter entrapped in guide section of valve plug.
• Aged and hardened gland packing, causing increased hysteresis
• Malfunctioning positioner (Check the positioner by operating it directly
on an air supply known to be operating normally.)
Fluid leak from gland section • Check for loose packing flange.
• Check for insufficient grease.
• Check for damaged valve shaft.
Liquid leak from gasket section • Check for Ioose nuts of bonnet.
• Check for defective gasket (deformed or damaged).

Azbil AMT Specifications

General

Brand	Azbil
Model	AMT
Category	Control Unit
Language	English