Paulsson:Environmental rooms

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  • Call HMS Facilities if there's a problem: x2-1901

Presented here is the sordid history of our environmental rooms, 405B (30 degree room) and 406B (25 degree microscope room):

Future: perfect harmony, constant temperature and humidity

Present: doubts remain

Past: turmoil


  • 406B

060321 - 061107 Many problems over the course of ~8 months. From charts over this period, there were 7 failures where the temperature rose and then fluctuated (sawtooth pattern), in the same manner observed when the compressor shut-off. There are also 6 events where the temperature rose and stayed high, presumably until the door was opened and/or the until was repaired. JP says that the original control box was faulty and that eventaully it was repaired.

070126 Temperature climbs rapidly to 36deg C then fluctuates between 40 and 33deg C for next 10h. Door opened. Compressor reset to repair?

March'07 Minus Eleven warranty expires.

070506 Temperature rises rapidly from 25 to 36 deg C then fluctuates between 36 and 32 deg C for the next 9h. When found we opened the door to the room and turned off Main. We are told the compressor shut-off (due to low water pressure) and it was manually reset to return to operation.

070508 Minus-Eleven installed an auto-reset on compressor. This will automatically turn compressor back on after it shuts-off due to low water pressure ( a safety feature that keeps the compressor from overheating should the flow of cooling water be shutoff). I really had to push for this as a solution, as it poses the risk of the comp[ressor burning itself out if there's no water for cooling, rather than just a temporary fluctuation in water pressure that trips the shut-off.

070701 Temperature climbed approx 5deg over 2hrs, then rapidly returned to 25deg and stayed there. Shay called facilities.

070704 Large change (temp steadily climbed to 40deg C over the course of 10h probably due to Juan turning of fans during an experiment and forgetting to turn them back on.

070705 Visit from Harris technician (name?) responsible for environmental rooms on campus. He will be performing regular maintenance on our room. He locked all but the set-point control on the instrument panel. He also went up and had a look around above the room. He thought that the auto-reset switch on the compressor should restart the compressor fast enough that only a tiny blip should be seen on the chart recorder (blip = 1-degrees in 15min, not 5deg over 2hrs).

070723 Temperature climbs to 30deg C over the course of an hour and returns to basline. (scheduled power shut-down?)

080212 Both rooms rise to 33deg C over the course of an hour and then return to baseline.

080503 Control panel failed at approximately 10pm on a Saturday night. Room got very hot, but we don't know how hot because control panel is also required for temperature read-out on chart recorder. Johan received call (in England) and asked that the door be propped open until the room was repaired. Monday morning: Shay said the room felt like it was at 40 degrees C with the door open!!! A new control panel was installed and the room returned to normal operation by 10am Monday (080505).

Follow-up: Barbara Grant was notified of the problem and she wrote to Rick Melin to ask what needs to be done to avoid future failures...
When I spoke to Rick on 080509 he said that Minus Eleven had replaced a "power supply" Monday morning.

080508 ~12:40pm high temp alarm sounds, door propped open, facilities called. The chart recorder also failed, so we don't know how high the room temperature was, but Shay felt that it was >40deg C when he opened the door to the room.
Room temperature stabilizes approximately 6pm Thursday.
Shay closes door Friday 8am. Temperature stable.
Facilities called Minus Eleven to come do the repair... they show-up ~11am on Friday (080509) and replace the "cycle relay" for cooling system. They don't talk to me (or anyone else in the lab) before, during, or after completing the repair. Instead I talk to the Johnson Controls guy who was here to check the working order of the alarm system. I call Rick Molin to find out what the status of the job is. WTF!!!
Ricks says that the Minus Eleven guy says these relays have a lifespan and will begin to fail sporadically, explaining why the room started working again without intervention. Will this relay be replaced preemptively on a schedule????? I got an equivocal response to this question from Rick.

080608 ~1pm, Sunday. Temperature climbed steadily to 30deg C then back to baseline. Occurred during heatwave when many rooms failed simultaneously, facilities responded quickly.

  • 405B specific problems

090108 ~7pm, Thursday. Humidity dropped to ~19%. Burak called facilities. They came promptly and called Harris (or Minus Eleven?). Problem was fixed by ~10:30pm Thursday and RH returned to 35%.


Airflow considerations

  • 20 cfm / person to stay well oxygenated
  • 50 cfm of house air in each room; the heaters/coolers treat this air to be at set point for the room
  • if rooms were turned off, ~400 cfm required for maintaining temperature in face of heating from humans and equipment
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