Since I could only change the flow at EY the way I wanted to, I manipulated only that flow rate. I turned it down from 12k CFM to 9.5k CFM last night to test stability (looks good), and so it is at 9.5k when I start and that is where I have left it. I think we should set all fans, except SF5 and SF6 to 9k or 9.5k CFM when we can. Here are the times:
EY:
17:02:30 From 9500 CFM (Vane position 40%) to 12000 CFM (70%)
17:14:15 Back to 9500 CFM
17:28:00 Change to 12000 CFM
17:41:56 Change to 9500 CFM
17:54:00 Change to 12000 CFM
18:08:00 Change to 9500 CFM
18:24:49 Change to 12000 CFM
18:39:10 Chnge to 9500 CFM
18:52:50 Change to 12000 CFM
19:09:15 Change to 9500 CFM
As noted above, I was unable to change the flow rates at the CS and EX, the two places that PEM injections suggested would be most sensitive to HVAC noise; I was able to change air flow rates at EY. There appears to be more scattered light at EY now than when I tested the damped cryobaffle in Sept. 2022 (Fig 1). But our PEM injections suggested that ambient vibration at EY would, nevertheless, not normally be limiting. This is consistent with my air flow manipulations – Fig 2 shows that there was very little if any improvement in range between 12000 CFM and 9500 CFM flow rates at EY.
PEM injections did, however, suggest that vibration at the corner station and EX may limit our range, always or on occasion. The 8 or 10 Mpc increase in range from the site HVAC shutdown is probably mainly associated with EX and CS. I suggest for now that the air flow rates be reduced to about 9k for each turbine, and I will study reduction in water flow etc. on my return.