Helium Liquefier Cooling Work Done On: 29-June-2022 and 5-July_2022 ------------------------------------------ Original Rev. 30-Jun-2022 Current Rev. 11-Jul-2022 Summary: this note describes work done on the water cooling system for the Main Compressor on 29-June and 5-July 2022. - The single Water Filter was replaced with dual parallel filters on 29-June-2022. - Except for the run from the Return Booster Pump Output up to the return to the BPS Process Water System in room B111 all of the old 1/2" ID cooling water components for the Main Compressor were replaced with 3/4" ID components on 29-June-2022. - On 5-July-2022 the final old 1/2" ID cooling water components were replaced with 3/4" ID components so that now the entire cooling circuit for the Main Compressor is 3/4" ID components. Some details of this work follow: --------------------------------- 1. Leading up to the work on 29-June-22 the single water filter on the main compressor had become very clogged. It had previously been replaced on 14-June-22 so it clogged up in just 2 weeks. A sketch of its history is: Flow Temp Rate Diff Cross Date LPM deg C Check ------- ---- ----- -------- 14 June 13.3 8.5 113.05 15 13.0 8.6 111.80 16 12.7 8.9 113.03 17 12.5 9.1 113.75 20 11.7 10.0 117.00 21 11.0 10.3 113.30 22 10.2 10.8 110.16 23 9.8 12.3 120.54 24 9.5 12.9 122.55 25 9.2 12.7 116.84 26 9.0 13.0 117.00 27 9.2 13.4 123.28 28 9.0 13.5 121.50 29 8.4 14.7 123.48 All readings taken while the Main Compressor was running and had been running for sometime. Cross-Check is just the product of flow rate and temp diff. If the heat input is constant then the flow rate times the temp difference should be constant. The flow meter in the old single filter setup was replaced with a new flow meter in the new parallel filter & mostly 3/4" ID setup on 29-June22. I doubt that the readings of these two flow meters can be directly compared but trying to compare them we see: Flow Temp Rate Diff Cross Date LPM deg C Check ------- ---- ----- -------- 29 June 15.0 7.2 108.0 30 June 15.0 7.2 108.0 So the cross checks are about the same and if anything the new flow meter probably reads a little low (e.g. 10%) compared to the old flow meter. 2. On 5-July-2022 now that we finally have a Main Compressor cooling loop with dual filters and all 3/4" ID components record the pressure gauges in the sub-basement under some test conditions: Cooling Water Pressures in PSI Gauge ---------------------------------------------------- Main Compressor Purifier ----------------------------- ------------------- Supply Pump Return Pump Supply Return ------------- ------------- Purifier Purifier Inlet Outlet Inlet Outlet Inlet Outlet ----- ------ ----- ------ -------- -------- Only Supply Valve Open 83 83 84 84 82 76 Pumps Off Only Return Valve Open 74 75 75 75 83 77 Pumps Off Supply and Return Open 81 82 76 75 83 77 Pumps Off Supply and Return Open 78 93 63 76 82 77 Pumps ON The water filter for the Purifier had just been replaced so this table indicates about the maximum flow through the Purifier. A main point of the data in this table is that running the new high flow rate through the Main Compressor does not appear to starve the Purifier of its cooling water. Back with the single filter and 1/2" ID loop for the Main Compressor the very lowest difference we saw between the compressor's inlet and outlet water temperatures was 8.5 to 9.0 deg with a brand new filter and its typical lowest temperature difference was about 10.0 degrees. Now with the dual filters and the all 3/4" ID components, in the first 3 days of running, I've seen inlet to outlet temperature differences in the range of: 5.9 to 6.5 degrees with an average of 6 readings of 6.3 degrees. So far with the new dual filter elements only in operation for one week I see no change in the flow meter when I valve Off either one of the filters. Now with dual filters and the all 3/4" components the new flow meter reads almost 17 LPM. 3. Over the 4th of July weekend and for part of the next week we had a couple of fairly long runs with: lots of recovered gas to liquefy, the Purifier remaining in mode 41, and no one taking liquid from the storage dewar. This gave us a chance to see how well the liquefier is operating compared with its 22 liters per day specification. From 18:15 on 30-June until 22:00 on 1-July we whet from 17.0 liters to 50.6 liters. This is 33.6 liters in 27.75 hours or a rate of 29 liters/day. From 22:30 on 2-July until 20:15 on 4-July we went from 13.0 liters to 63.8 liters. This is 60.8 liters in 45.75 hours or a rate of 31.5 liters/day. From 9:15 on 6-July until 9:45 on 7-July we went from 32.0 liters to 62.7 liters. This is 30.7 liters in 24.5 hours or a rate of 30.1 liters/day. From 9:45 on 7-July until 17:45 on 8-July we went from 62.7 liters to 104.1 liters. This is 41.4 liters in 32 hours or a rate of 31.1 liters/day. These rates seem high but at least they do not indicate any known problem with the liguefier. The last two readings are adjacent to each other from one long run and these two liquefication rates look about the same. 4. The Purifier did an automatic pump out of its cold trap absorber starting sometime late on 4-July or early on 5-July. That internal automatic pump out of its cold trap brought the Purifier's cold temperatures up to 278 / 299 degrees. This "Pump Trap" mode is mode 71. Mode 11 "Cool Down" started at about 11 AM on 5-July and went to mode 21 "Cool Down" by 16:00. The Purifier was back in mode 41 "Steady State Purification" by about 20:00 that day. So the "Cool Down" and "Transition to Purification" took about 9 hours plus or minus an hour or two. The cold temperature before this automatic internal cold trap pump out were about: 103 / 64 or 105 / 65. In the 2 days since this automatic cold trap pump out the Purifier's cold temps have been: 104 / 65. So the vacuum jacket seems to be not perfect but it's OK. Before the most recent vacuum jacket pump out the Purifier's cold temps were: 123 / 77. Right after the most recent vacuum jacket pump out the Purifier's cold temps were: 80 / 57. The most recent vacuum jacket pump out was on 14-Apr-2022. 5. The Purifier did another automatic pump out of its cold trap absorber probably starting sometime early on 9-July. By about 13:40 that afternoon it had cooled back down and I got to watch it make the transition from Mode 31 "Transition to Purification" to Mode 41 "Steady State Purification". It made this transition from Mode 31 to Mode 41 when its cold temperatures changed from 161/79 to 160/79. So its clear that the Counter Flow cold temperature threshold is 160 deg K. From the readings one would guess that the Cold Trap temperature threshold is 80 deg K.