In systems where other supply lines are unavailable, gas-over-hydraulic actuators (also called gas-over-oil actuators) use gas to power the hydraulic actuator that operates the valve. They can be paired with linear or rotary valves, are available for both high- and low-pressure control systems, and can be supplied with various control options.
There are three main ways a gas-over-hydraulic actuator can stop working:
- A newly installed valve or actuator won’t turn, or the actuator turns without the valve.
- The actuator won’t turn the valve
- The actuator won’t turn with the hand pump.
The guide below explains the most common causes of these three problems and what you can do about them.
Problem 1: A newly installed valve or actuator won’t turn, or the actuator turns without the valve.
Cause |
Solution |
|---|---|
|
The actuator and the valve aren’t in the same orientation. |
Check the orientation by removing either the actuator or the protective cover. Use the hand pump to align the valve and the actuator in the same orientation. |
|
The key is not installed. |
Inspect by removing either the actuator or the protective cover. Install key. |
|
There are shipping plugs in the gas supply, exhaust ports, or tubing connected to the gas hydraulic tanks. |
Inspect the power gas and exhaust ports. Remove plugs if present. Also remove shipping plug caps from the gas hydraulic tanks and tubing. |
|
The power gas pressure is too low. |
Ensure that the power gas tubing is of sufficient size. Check torque requirements. |
Problem 2: The actuator won’t turn the valve.
Cause |
Solution |
|---|---|
| The power gas pressure is too low. | Turn the power gas up if possible. Check torque requirements. |
|
The speed controls are closed. |
Open the speed controls and ensure that the lock nut is tight. |
|
The valve is stuck. |
Flush and lube the valve. If this doesn’t solve the problem, remove the actuator from the valve and test it independently to identify whether the problem is stemming from the actuator or from the valve itself. |
Problem 3: The actuator won’t turn with the hand pump.
Cause |
Solution |
|---|---|
|
The hydraulic fluid level is too low. |
Check the fluid levels in the G/H tanks and fill to the manufacturer-recommended level. |
|
The hand pump has failed. |
Troubleshoot the hand pump and recondition as needed. |
|
The actuator seals have failed. |
After ruling out all other causes, it may be necessary to rebuild the actuator. |