We tested the actuation of the M9/M20 beam blockers on the T2 monolith (3-4pm).

Vacuum levels remained steady throughout so the M20 o-ring replacement that was performed this shutdown was successful (see strip of 1ACG4 - vacuum gauge for T2 systems interlock).

Note: M20 was actuated by contacting the control room, while M9 (labeled T2 blocker) was actuated through the physical ASU on the ground level of the meson hall (see picture).

For future shutdown work: the air supply valve must be kept open (tab lifted up), otherwise the solenoids won't see pressurized air. 

We ran into issues because the tab on the valve broke early into the shutdown and we didn't realize that it had to stay in the open position. 

Note: The flow on the T2 demin line went up to 1.5 gpm yesterday when we were on the blocks. The needle valve was likely nudged on accident.

Update:

1) the T2 demin flow was corrected and the air supply tab was replaced - see picture M20

2) T2 BB actuated successfully with replacement tab - vacuum remained stable

3) slow leaking valve connections were tightened again

4) water level in expansion tank corrected to just below 40 cm