Installed a new MKS gauge at cross C-4, to do the installation I closed two gate valves for the filter cavity tube, FCV-6 and FCV-9, these valves isolated the volume I was working on and left a gauge that gave me the vacuum pressure in the area that I was working, the pressure was actively monitored, no changes noted.

To install the gauge a metal valve and a T were added to the configuration, the system was pumped down and leak tested, and no leak was noted above 1.0x10^-10 torr*l/sec.

To finish the installation for now, the new volume was pumped down, and remains isolated from the main volume.  Then FCV-6 and FCV-9 were open.