We plan to fill our recycle process water tank from three of our process machine overflow tanks. We don't require tight level control or flow split.

I was planning to wire an analog output in series with 3 I/P's and then send the pneumatic air signals out to the valve positioners on each machine.

When I reviewed the specs for the I/P and the positioners, it looks like a single I/P is more than adequate to handle the signal air flow requirement to all 3 positioners. Now I'm thinking that I will connect the pneumatic tubing for all 3 valve poitioners to a single I/P.

Does anyone have a previous bad experience or see any pitfalls with paralleling the 3 positioners.

Thanks

 

Pneumatic modulating valves seem to vary significantly in their initial or breakaway pressure (the pressure you have to send just to get them to lift off the seat). If you had separate I/P's with a common 4-20 or separate I/P's with separate 4-20s, you could correct for any differences from actuator to actuator. Other than that, I see no problem.

 

It's unlikely that they would move in unison or even very close, but if that's not a problem and you have enough flow it should work.

Regards
cww

 

I don't see a problem you should be able to adjust the 3 positioners to give roughly the same flow.

Electro-pneumatic positioners would also work, they could be wired in series or from 3 different outputs.

 

I do not see any problem, positioners will work slightly slower depending on length of tubing for each positioner.