Mention the different types of problems faced with control valve actuators used in industries.
Pneumatic actuators
BOTH PNEUMATIC ROTARY AND PNEUMATIC CYLINDER ACTUATORS
- The valve is binding.
- The motive pressure is incorrect.
- The solenoid voltage is incorrect.
- The solenoid ports are plugged.
PNEUMATIC ROTARY ACTUATORS
- The system leakage in front of the actuator is not allowing the minimum SCFM (standard cubic feet per minute) for operation.
- The system or actuator filter is blocked or clogged.
- The actuator ports are plugged with contaminants.
- The speed controls are closed.
- There is too much condensation.
- The spring return units have broken springs.
- There are problems with the seals.
- The actuators are undersized.
PNEUMATIC CYLINDER ACTUATORS
- Air is leaking at the piston guide bushings.
- There is increased thrust due to valve issues.
- There is excessive side loading in rotary applications.
- The piston seals are leaking.
Electric, or motor-operated-valve (MOV), actuators
ELECTRICAL ISSUES
- The power voltage isn’t correct.
- The control voltage isn’t correct.
- The fuse has blown.
- There is a power board failure.
- The wire has become fused or disconnected.
- The thermal overload is engaged.
- The power phasing is incorrect.
- The limit switch is not set correctly.
- The quick disconnect harness is loose.
MECHANICAL ISSUES
- There are problems with the valve binding or the stem.
- There are problems with the drive nut.
- The center column gear is stripped.
- The motor pinion / worm gear is stripped.
- The torque switch is engaged.
- The handwheel declutch has failed.
Gas-over-hydraulic, or gas-over-oil, actuators
- The valve and the actuator aren’t in the same orientation.
- The key is not installed.
- There are shipping plugs in the gas supply, exhaust ports, or tubing connected to the gas hydraulic tanks.
- The power gas pressure is too low.
- The speed controls are closed.
- The valve is stuck.
- The hydraulic fluid level is too low.
- The hand pump has failed.
- The actuator seals have failed.