Hi Lorin,I'll do my best to explain.Instrument air was disconnected to fit an isolation valve, as two valve controllers where sharing 1 supply. The isolation valves were fitted no problem but when Instrument air was turned back on, the problems started.The valve is fully closed (4ma) but the feedback arm appears to be at 100%. When DCS send a 25% (8ma), 50% (12ma) and 75% (16ma) the valve doesn't respond. We are seeing the signal at the controller and on the dcs screen but the valve doesnt opperate.That said with a 100% (20ma) signal the valve shoots open.Also I don't know if i just haven't noticed this before but the fieldvue is constantly hissing (air leak)?
THIS IS HAPPENING WITH BOTH VALVES THAT HAD ISOLATION'S FITTED?
Hi Lorin, I'll do my best to explain. Instrument air was disconnected to fit an isolation valve, as two valve controllers where sharing 1 supply. The isolation valves were fitted no problem but when Instrument air was turned back on, the problems started. The valve is fully closed (4ma) but the feedback arm appears to be at 100%. When DCS send a 25% (8ma), 50% (12ma) and 75% (16ma) the valve doesn't respond. We are seeing the signal at the controller and on the dcs screen but the valve doesnt opperate. That said with a 100% (20ma) signal the valve shoots open. Also I don't know if i just haven't noticed this before but the fieldvue is constantly hissing (air leak)?
The snap-acting response is most likely because the instrument is going into cutoff and driving the instrument hard to respond. When it’s in this mode, tuning is ignored – the instrument goes to full air output. I’m curious as to the performance of the assemblies prior to the changes made, as well as the pneumatic hookup scheme. Why don’t you give me a call and let’s talk through this further. Work phone = 641-754-2631 Lorin Lorin Miller | Director of Marketing, FIELDVUE Instruments | Fisher Emerson Process Management | 205 S. Center Street | Marshalltown | IA | 50158-0190 | USA T +1 641 754 2631 lorin.miller@emerson.com FIELDVUE Instruments. Over one million strong and growing. <image001.jpg> <image002.jpg> <image003.jpg> <image004.jpg> From: sherlock0486 [mailto:bounce-sherlock0486@community.emerson.com] Sent: Wednesday, October 09, 2013 11:25 AM To: DVC@community.emerson.com Subject: [EE365 Valve Controllers & Positioners Track] Cont. Hi Lorin, I'll do my best to explain. Instrument air was disconnected to fit an isolation valve, as two valve controllers where sharing 1 supply. The isolation valves were fitted no problem but when Instrument air was turned back on, the problems started. The valve is fully closed (4ma) but the feedback arm appears to be at 100%. When DCS send a 25% (8ma), 50% (12ma) and 75% (16ma) the valve doesn't respond. We are seeing the signal at the controller and on the dcs screen but the valve doesnt opperate. That said with a 100% (20ma) signal the valve shoots open. Also I don't know if i just haven't noticed this before but the fieldvue is constantly hissing (air leak)? THIS IS HAPPENING WITH BOTH VALVES THAT HAD ISOLATION'S FITTED?