One important thing to note is that the difference between the upper bench value & the regulator pressure determines your seat load on an air-to-close valve assembly, so the limit on the upper bench value should be +0/-(the tolerance value) ensuring there will be adequate Force to seat the plug. Also the regulator should be set with a -0/+(tolerance value) again to assure necessary seat load. To increase seat load, decrease the bench set or increase the regulator pressure setting; conversely, to lower seat load, increase the bench set or decrease the regulator value, or a combination of both.
Yes, seat loading is what makes the bench set so critical. On a direct acting actuator the seat loading is supplied by the amount of pressure available over the upper bench. For a class III and IV shutoff there must be 40lbs of available force for every inch of circumference. That force requirement is divided by the effective diaphragm area to come up with a pressure value. This value represents the amount of air pressure in excess of the upper bench value you need to achieve the total force requirement.
@@jimdiggins101 i agree, good video & great to talk to someone who understands actuators, valves & specifications. Look forward to seeing more of your videos? I wrote a lessonplan on AOVs for I&C that I’d like to send you, just provide me an email address and I’ll be happy to send it your way, Ok?
Good video. Once everything is coupled and let's say the valve starts closing at 8 psi instead of 6 psi (stem friction etc). Do you readjust the spring tension while coupled to match the bench set stated on the nameplate or do you leave it as is?
Leave it as is. The bench set represents the preloading of the spring and ensures proper operation and adequate seat loading. You can, however, repeat the bench set test with the valve coupled to the actuator for the purpose of gathering friction data. This data can be used to drive preventative maintenance and diagnose the root cause of loop oscillations. A good valve positioner unit will perform this test automatically.
Im having issues with a valve currently for leaking by. Hard to find the right kits or someone is not getting the right info for them. Is there a website or something to find the right kits? Based in west texas.
The jams keep the connection block in place In most applications, the feedback arm connects to the block. In some cases, even a slight rotation can create feedback error or loss of position indication.
One important thing to note is that the difference between the upper bench value & the regulator pressure determines your seat load on an air-to-close valve assembly, so the limit on the upper bench value should be +0/-(the tolerance value) ensuring there will be adequate Force to seat the plug. Also the regulator should be set with a -0/+(tolerance value) again to assure necessary seat load. To increase seat load, decrease the bench set or increase the regulator pressure setting; conversely, to lower seat load, increase the bench set or decrease the regulator value, or a combination of both.
Yes, seat loading is what makes the bench set so critical. On a direct acting actuator the seat loading is supplied by the amount of pressure available over the upper bench. For a class III and IV shutoff there must be 40lbs of available force for every inch of circumference. That force requirement is divided by the effective diaphragm area to come up with a pressure value. This value represents the amount of air pressure in excess of the upper bench value you need to achieve the total force requirement.
@@jimdiggins101 i agree, good video & great to talk to someone who understands actuators, valves & specifications. Look forward to seeing more of your videos? I wrote a lessonplan on AOVs for I&C that I’d like to send you, just provide me an email address and I’ll be happy to send it your way, Ok?
Sounds good. My contact info is available on my UA-cam page.
Need some videos of repairs out in the field
Good video. Once everything is coupled and let's say the valve starts closing at 8 psi instead of 6 psi (stem friction etc). Do you readjust the spring tension while coupled to match the bench set stated on the nameplate or do you leave it as is?
Leave it as is. The bench set represents the preloading of the spring and ensures proper operation and adequate seat loading. You can, however, repeat the bench set test with the valve coupled to the actuator for the purpose of gathering friction data. This data can be used to drive preventative maintenance and diagnose the root cause of loop oscillations. A good valve positioner unit will perform this test automatically.
Thanks bro!
You betcha!
Im having issues with a valve currently for leaking by. Hard to find the right kits or someone is not getting the right info for them. Is there a website or something to find the right kits? Based in west texas.
Emerson owns Fisher Valves. From the Emerson website you can find the local business partner as well as drawings.
How tight should the jams be tightened. What are the risks of not setting the jam nuts?
The jams keep the connection block in place In most applications, the feedback arm connects to the block. In some cases, even a slight rotation can create feedback error or loss of position indication.
Jim, is there any way to contact you outside of UA-cam? I have an issue with one of our diaphragm actuators I would like to discuss with you.
My contact info is listed on my UA-cam home page.
@@jimdiggins101 Thanks. I just sent you an email.
Like Video.