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Entry  Mon Oct 6 10:04:58 2014, manasa, Update, General, Unexpected power shutdown 
    Reply  Mon Oct 6 10:23:43 2014, Steve, Update, VAC, Unexpected power shutdown 
       Reply  Tue Oct 7 16:55:16 2014, Steve, Update, VAC, Unexpected sweaty valves sweatyV5.jpgsweatyV5f.jpg
          Reply  Wed Oct 8 08:46:57 2014, Steve, Update, VAC, VAT valves actuator lubricant 
             Reply  Mon Oct 13 14:44:52 2014, Steve, Update, VAC, RGA scan pd78 -day 13 RGAscan13Oct2014.png
                Reply  Mon Dec 1 17:13:57 2014, Steve, Update, VAC, RGA scan pd78 -day 63 RGAscanD63.png
                   Reply  Tue Mar 31 09:03:32 2015, Steve, Update, VAC, RGA scan pd78 day 182 RGApd78d182.png
                      Reply  Wed Jul 1 10:01:25 2015, Steve, Update, VAC, RGA scan pd78 day 275 rga275d.png
                         Reply  Mon Oct 5 10:11:35 2015, Steve, Update, VAC, RGA scan pd78 day 386 RGA_background.png
       Reply  Tue Dec 23 14:33:24 2014, Steve, Update, VAC, Chiara gets UPS prepUP.png
    Reply  Mon Oct 6 10:28:18 2014, manasa, Update, General, Unexpected power shutdown 
       Reply  Mon Oct 6 11:09:52 2014, Jenne, Update, General, Unexpected power shutdown: slow computers 
       Reply  Mon Oct 6 17:04:51 2014, ericq, Update, General, Unexpected power shutdown 
          Reply  Mon Oct 6 17:36:17 2014, ericq, Update, General, Unexpected power shutdown 
          Reply  Mon Oct 6 18:15:12 2014, manasa, Update, General, Unexpected power shutdown: end green alignment 
    Reply  Tue Oct 7 16:17:15 2014, Steve, Update, General, reason for 8 sec power outage 
Message ID: 10584     Entry time: Wed Oct 8 08:46:57 2014     In reply to: 10579     Reply to this: 10599
Author: Steve 
Type: Update 
Category: VAC 
Subject: VAT valves actuator lubricant 

Quote:

 Pump  spool valves V5, V4, V3 sweating a lot. VM3 and VC2 not so much.

They are VAT valves F28-62887-03, 11, 14 and so on ~15-16 years old.

 I'm speculating that some plastic is aging-braking down at the atmospheric-pneumatic side of valves.
The vacuum side is not effected, according to vacuum pressure readings.

May be some condensation from the small turbos? No

I'm looking for an identical valve to examine, but I can not find one.

We are using industrial grade 99.96% Nitrogen to actuate these valves.

Valves are not effected are  dry: VA6, V6, V7 and all annuloses.

 

VAT's answer:

Yes, our engineers are aware of this issue.  They say:

The pneumatic actuator needs lubricant as the O-ring (Viton) slides in the cylinder. Without grease the O-ring would be abraded and leaking after only a relatively few cycles.  The lubricant used in our pneumatic actuators is an emulsion of oil and Teflon flakes.   Vibration, many cycles and sometimes high temperature lead to the separation of the oil and Teflon.   That is apparently the issue you are seeing.

VAT is and has been testing and qualifying new lubricants, and this is one of the factors we are always looking to improve.  The formula we used 15 years ago in these valves seems to have performed reasonable  well.  Our formula today should perform even better.

We realize this explanation does not help you with these existing valves, but 15 years of service is not too bad is it? 

Steve -NOTE:bonnet seal is metal so there is no way this oil can get into our vacuum ( only if the bellow leaks )

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