Searching for a replacement valve for a simple application while re-designing the system. System uses piping connections to monitor system pressure. The instrumentation lines are frequently dumped and must be vented of all gas bubbles leaving only water in the instrument lines for startup. Control valves (remotely operated) are used for this venting. Dependability, longevity, low maintenance are needed. I have found a very simple solution in coaxial valves such as this:

Due to its simplicity (one moving part) it is said to be extremely reliable and requiring no maintenance other than external inspections. It can be set up to be pneumatically operated by an electrically operated pilot valve and can be set up with a proximity switch to indicate position. Our past solution has been an electrically operated (90 degree) rotary positioner on a ball valve.
What has been your experience with coax valves? Are they reliable? Any problems with air leaks? Who manufactures them? I am anxious for first hand information. (Should this be posted in a different section?)
Thanks.
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