Maintenance for M15

During the run last year the M15 Separator #1 Argon flow Piezo-Electric valve started to leak Argon gas through the valve. With the valve closed the pressure in the Separator will not go below 3 x 10-5 Torr, not good enough to satisfy the "good vacuum" interlock on the high voltage supplies. We continued to operate in Argon mode or  in vacuum mode by maually closing the shutoff valve above the Piezo-electric. During the shutdown Rahim and Deepak removed the valve in question and placed it on the leak detector, they made very small adjustment to one of the screws (see attached picture red circle) so that no helium gas leaked through the valve. Also, the spare valve was fixed by adjusting all three screws, so it opened when the Argon flow was turned on from EPICS and closed when the flow was turned off. Both valves were then installed on the Separator and tested. When the Argon flow is turned off (vacuum mode) the pressure is about 3.4 x 10-6 Torr, with the valves open (Argon mode)  the pressure in the Separators is about 1.2 x 10-4 torr and is regulated by the Omega controller.