Actuator repacement 2

[samsarani]

Dear Sir and specialists
HI

I ask question about changing the actuator of ON/OFF valves. We have many on/off valve in our gas treatment plant and some actuators were damaged and need to use spare parts for some of them and some item we will replace actuator totally. Also we have drawing of valve and some information (e.g force to open and force to close). First my question is: could we replace these actuators with new and another brand? Is there any restriction for replacement?

And second question is: supply spare part for some item is difficult, could we use some spare part from another brands?
Thanks for your helps

 

[NGiLuzzu]

samsarani,
first of all, I believe You should make distinction between rising stem and quarter turn valves, and between position seated and force/torque seated ones (if applicable) and make sure to understand the relevant differences in actuation requirements (for example: force/torque seated valves usually need a little over-travel beyond 0° closed position, while position seated don't; ball valves require a certain amount of torque along the whole 0° to 90° rotation, while triple offset valves have negligible running torques if compared with ones to open or to close, that show up near the 0° closure position only; and so on...).

Then You should check to have all the force/torque figures, for both the valve requirement (from the Valve Manufacturers) and the actuator output (from the Actuator Manufacturer, whoever he is), in order to make them match correctly.

Once You have selected an actuator that gives each valve the proper forces or torques, You can proceed procuring and assembling...
I would advise against mixing parts from different Manufacturers, at least beacause that would broke any guarantees and make the machine performances unpredictable (not to mention other possible drawbacks...).


Hope this helps,
'NGL
__________________________

 

[JLSeagull]

You can replace the bad actuators with new actuators using a different manufacturer. You know the torque required by the valve. Let's assuem that you need a single acting spring return scoth yoke style actuator for a rotating ball or butterfly valve. Select the actuator with a balance of spring and piston forces that well exceed the valve torque based upon your minimum air supply. I normally use a valve automation house to provide the assembled valve and actuator including all accessories and testing. You can send the valve model, minimum air supply and torque requirements to an automated valve packager and request them to select the actuator. Also advise if you need open and closed position switches, position indicator and any specific language, solenoid valve and voltage, etc.

 

[gerhardl]

In addition to above: do not forget to specify necessary opening and closing times when selecting new actuators. Very often the process do not need a very fast opening and closing time, and you can select smaller actuators combined with external gear.

On the other hand: if you do this, check if opening and closing failure alarms in the system is time based. You do not want to create an alarm by closing too slow.

Most often it is most practical to take a valve out of the system to check operation when mounting a new actuator,if possible.

Good luck!

For some cheaper valves the actuator will cost considerably more than the valve. if this is the case you will be better off changing both valve and actuator.

If the motorized actuator has had a short lifetime, (normal lifetime for good motorized actuators should be (say) 10 to 20 years or more), you should also check quality, operation mode, suitability and advicement from producer on expected lifetime depending on number of operations.

 

[cjeane01]

One of the big issues of changing out actuators verses replacing in kind is the mounting hardware between the valve and actuator. Most valves and actuators now are using a ISO standard for mounting pad dimensions, however the valve stem height, diameter, and connection type are very different and may require modification or even new hardware.