1. ACTR Project #477 - Increase Cooling of Blanco Dome Update: Brooke Gregory 9Apr2015

2. Remaining tasks (FCS): Leyton contract Some work on the insulation of the water/glycol lines remains. Lately Benjamin has been called to work on other urgent Tololo/LSST projects (San Carlos water supply problems; fence for new dump area for LSST). Since the insulation work is not high priority, we have not objected.

3. Remaining tasks (FCS): Sensors and controls (Edison) AHU flow sensor problems continue. We still do not have reasonable measurements of the flow at the AHUs, though it is apparent that cooling is quite effective Conclusions Hypotheses: Flow is lower than range covered by sensor. (We know that the sensors are only marginally sensitive to the flow rates we expect) Air in lines is limiting flow Plan: Install sensor with lower flow floor (to be able to better diagnose the situation) This requires enlarging hole in 2” lines at AHUS (awkward but possible) Purge lines of air: Refill with better technique Improved bleed valves Install auto bleed valves

4. Remaining tasks (FCS & BCS)… Once the dust settles, renew water/glycol in system New Glycol has been received. We have also ordered more. Renew fluid in both systems FCS – easy BCS – wait for engineering shutdown Install flow meter for BCS. Candidate activity for engineering shutdown at end of Jul2015? Replace and/or refurbish various temperature and pressure gauges in the plant (low priority).

5. Ongoing…Documentation Rodrigo Leiva has been working on a new document that supersedes (though does not completely replace) one of the historic documents (1965) describing the water/glycol system This work is almost complete as far as providing a consistent picture of the piping as far as we know it. Rodrigo is about will continue as resources permit until TELOPS is satisfied that they have the reference they need to support the system. Improvements over previous documentation: Labelling of piping. Largely done. Legibility: rough 3-D “cartoon” of piping facilitate visualizing physical piping. (In progress.)

6. Unresolved: An operation error with the FCS on 10Dec revealed an unidentified connection between the circuits. Where is it? Eliminate it (or control it).

7. High Priority: Define what we can and cannot do during July engineering. Candidates (no priority implied): Experiments (TBD) to find BCS/FCS coupling Install venting/expansion tank for BCS Replace glycol in BCS Install flow meter in BCS (at chiller plant)