For the records, and in order for us to define new threshold values, I am posting here the pressure fluctuations for all the BSC-ISI pods (L4C, GS13 and T240), for all units on both sites (I will link this to the LLO log).
The first table attached shows the variations of pressure and the average leak rates for LHO. The L4C varies more than the GS13. The T240 pressure readout is pretty much the same than six months ago.
In this sample of data, we observe larger fluctuations at LLO than LHO, in all pods. The variations are however very similar within all the pods of a given chamber. So it is likely temperature related.
The last table compares the average variations and apparent leak rate for both sites.
Here are the HAM-ISI pods pressure. The comments made for the BSC-ISI pods hold for the HAM-ISI pods.
To summarize on this issue:
- We checked all pods on both sites. The trends are similar within the pods of a given chamber, so pods are likely not leaking. No pod show anornally low pressure (by comparison with other pods).
- John is looking into the RGAs to confirm there is actually no problem
- SEI is going to update the threshold parameters turning on the red lights
- DetChar is setting up automated monitoring
RGA scan posted at https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=14489