This morning, in accordance with LHO's move to Phase 3 operations of our COVID-19 response, I shut down the PSL (WP 8581). All stabilization loops (PMC, ISS, FSS) were disabled, then the laser was shut down; both shutters (external and 35W internal) are closed. The chillers remain on for the moment, they will be shut down and drained by J. Bartlett and R. Savage at a later date.
This is now a Part 1 of 1. In discussion this morning among the PSL team, we decided to leave the chillers on and request that staff already onsite for other maintenance activities (VAC, FAC, etc.) check on the chillers to top them off. This decision was made to minimize overall staff time onsite.
While doing final prep this morning for the chiller drain tomorrow, it became clear that draining them was a larger job than originally anticipated, 4+ hours for 2 people (8+ person hours). Therefore, in keeping with LHO's stance on Phase 3 operations, we decided that staff already onsite spending 2-5 minutes to check on the chillers every other week was a better method to minimize onsite time versus two PSL personnel spending 4+ hours to drain the chillers. To meet the same person time onsite as draining the chillers (8 person hours, best case), it would take someone already onsite 96 visits to the PSL chillers (assuming 5 minutes/visit). With a 5 minute check every 2 weeks (twice/month), we would have to be shut down and performing these checks for 48 months (i.e. 4 years, or until April 2024) to equal the person time required to drain them. Big difference in person time onsite by leaving the chillers running.
Should it become necessary in the future we will drain the chillers, but for now they will remain ON. PSL personnel have the capability to monitor the chillers remotely, so we will do so.
This now completes LHO WP 8581.