bubba.gateley@LIGO.ORG - posted 16:13, Wednesday 20 December 2017 - last comment - 10:16, Thursday 21 December 2017(39848)
BSC 1 North Door
While installing the north door on BSC 1 this morning, as we were inspecting the flange, I saw what appeared to be a rust spot on the flange in the sealing area of the inner O-ring at roughly the 5 o clock position (facing the BSC from inside the biergarten). I wiped, rubbed, and wiped again. I repeated this several times. There was no drag felt on the alcohol wipe, or on my clean gloves, no "rust residue" or any other foreign material came off on the wipe or glove. I put a piece of tape on the bolt head located near this position and showed Kyle the picture. Kyle said he would make a comment on this post.
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The area of interest bridges the inner O-ring contact patch and might result in an inner O-ring leak. We began pumping the annulus space soon after this door was installed and will be able to get useful information via the pressure data as we will have atmosphere on the VE side of this inner O-ring for the next several days. Though undesirable, an inner O-ring leak wouldn't require immediate attention as would a leak across an outer O-ring. The main issue resulting from an inner O-ring leak is the scenario where relatively large amounts of air get introduced into the annulus volume as part of an annulus ion pump replacement. We have work-arounds for this case and, as a matter of policy, always assume that an inner O-ring leak exists when replacing ion pumps or otherwise have a need to introduce air into an annulus space.
Squashed bug? Who did I leave the stoning tools with?
John, I have the stones
4.4 x 10-6 Torr this morning at the cart backing the locally mounted turbo ("hung" turbo). This is excellent for the vent/pump duration.