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The low-Z XAS hutch configuration consists of two separate Helium gas spaces. The front end / I0 section is supplied by SSRL house helium supply, while the low-Z sample box section is supplied by the Helium cylinder in the hallway behind the 4-3 blue electronics racks. The two sections are separated by a thin polypropylene film inside a clamped O-ring assembly as indicated in the picture.
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Remove one of the two paddles from the low-Z sample box and observe the flowmeter on the front/end I0 section. If the flow drops to zero, then there is a leak between the two sections, and you will need to change the polypropylene film.
To replace the polypropylene film and fix the leak between sections:
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Test that the two gas sections are separated again. To do this, check that the He flowmeter is at a high value (it reads "H +F" above 500) and decreasing. The initial high value is because there is heavier gas (air) being purged out of the Front end / I0 section. It should eventually settle around 200-240 when only Helium is in the front end / I0 section. If the flowmeter value is already lower than this after clamping, this means there is a hole in the film. This often happens because the O-ring can cut the film. No worries! Just unclamp the assembly, replace the film, clamp and test again!
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