Reports until 10:05, Wednesday 16 April 2025
LHO VE
janos.csizmazia@LIGO.ORG - posted 10:05, Wednesday 16 April 2025 - last comment - 10:40, Thursday 17 April 2025(83951)
Intentional pressure spike at the X-manifold
Janos - 9:50, LVEA

The X-manifold is valved out from the main volume both sides, the main turbo is pumping on it.
On the X-manifold I slightly opened up the suspicious blanked-off small Varian gate valve (see photo), to find out if it is opened or closed.
I moved very slowly the hand-actuator, and the pressure spiked up to the E-5s, then it immediately started to go down, now it is already at ~3E-7 (the initial value was ~1E-7).
So, the valve was closed and blanked off, therefore it wasn't stored appropriately, thus at the next opportunity (when the X-manifold will be vented), it will be removed, and blanked off.
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janos.csizmazia@LIGO.ORG - 10:40, Thursday 17 April 2025 (83971)
The handler of this valve was torqued, and the pressure in the X-manifold fell to 8.14E-8 Torr, and it is seemingly stabilized. Before poking with this valve, the pressure was 1.04E-7 Torr (and still rising), so there was indeed a leak from this valve to the system, as this torquing means ~20% reduce in gas load.
We do a comprehensive leak check on the X-manifold during the rest of the week, so this valve with all adjacent flanges will be bagged and leak checked.
We are also considering putting an adapter on the valve instead of a blank, and pump it down, so the lower pressure in the outer side of the valve could help, if there is still some communication between the valve and the system - but of course, it depends on the result of the leak check.

Finally, the handler of this valve was LOTO-d - it was simply taken off, so there will be no accidental moving of this valve anymore.
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