About a year ago, we published a blog post called 40 Reasons Your Actuator Isn’t Working. Since then, the article has generated thousands of views, and it continues to get hundreds more every month.
While there may be 40 reasons valve actuators may stop working, there are really only a handful of components that can cause the problems. So, if you have an actuator on the fritz, here are the five things you need to check.
What manifests as an actuator problem may actually be a valve problem. Our service experts report that this is the case 7 out of 10 times they are called about a faulty actuator.
Some common valve issues that can cause actuator problems:
A worn out valve stem
Seized up packing
Too much torque
It doesn’t do any good to repair an actuator when the valve is what’s causing the trouble. On the contrary, it wastes both time and money — and leaves you back where you started.
So, before you start tearing apart your actuator, first put the unit into manual override and see if you can operate the valve manually (this is only possible for electric actuators). If the valve still doesn’t move, then the problem is most likely the valve. If the valve does operate in manual mode, then you may have an actuator problem.
Actuators only have four major components that can break down and require repair.
The center column drive
An actuator opens and closes a valve by acting on the valve stem. This is the job of the center column drive, and this drive can break. However, this is a very rare occurrence, and not the mostly likely cause of actuator issues.
The connection to the valve
Much more likely is that the connection to the valve — the drive nut — has failed. A worn out actuator drive nut will not move the valve stem properly. You can see this by removing the center column cover and looking down the center to the valve stem.
The motor contactor is an electric actuator internal electrical part that tells the actuator to open or close the valve when given an input signal. If it fails, the actuator will not function. The contactor is also fuse protected, so check the fuses first!
On an electric actuator, the motor provides the torque to operate the valve. If the motor fails, the valve isn’t going anywhere. In this case, verify that the duty cycle and insulation class are sufficient for the application.
And that’s basically it! Everything else is bulletproof.
In terms of repair work, every circumstance is unique. If it’s possible to lock out the actuator electrically so there is no current, it may be possible to perform the repairs on-site. For example, if you need a new motor or contactor, a technician will often be able to replace the parts without shutting down the whole line.
On the other hand, for mechanical work like replacing the center column, you’ll likely need to remove the actuator from service before it can be repaired.
The extent of the repairs is also partially dependent on the type of valve the actuator is paired with. For example, to repair the actuator on a gate valve, you typically need to take the entire unit out of service and shut down the line.
If you need help diagnosing exactly what part of your actuator or valve unit is causing you trouble, give us a call. Our actuation experts can provide phone support and, if necessary, we can dispatch a service technician to your location to get you back up and running as quickly as possible.