Wire Chamber Gas Handling System
- Users should not be changing cylinders out or changing settings
- Users are not to change any of the regulator settings. Do not change the helium flow meter settings. If problems develop with the gas system contact Andy Kenyon (544-4752) or Walter Kellner (592-1527).
- Unless it is an emergency and all cylinders in a bank are empty do not change them out.
- There are two helium bottles connected together in parallel to provide helium to the dump shroud. Unless both bottles are empty do not change the bottles. The helium has no effect on the experiment anyway.
- Do not change ethane bottles out. If you think a bottle is empty contact Walter or Andy.
The blue panel just right of the left console shows Gas System Alarms. So far two types of alarm states have been observed
1. Red "LOW PSI" indicator light and really annoying sound
- From the HV GUI turn OFF all high voltages to the wire chambers, HDC1&2 and EDC 1&2.
- Check the alarm status on the upper of the two the GASMASTER panels. The "normal" status seems to be:
- Shed (Low RED LED): any higher than that is indication of a problem that requires attention; call RC.
- HMS (Low RED LED)
- SOS (fault orange LED)
- Unused (fault orange LED)
- From the key box, take the key to the gas shed.
- First, from the cage behind the shed, check whether Argon and Ethan pressure regulators indicate sufficient pressure.
- Check the display of the Gas Mixer. Most likely you read zero flow on channels 1 & 2 and a low pressure (<500 Torr)
- If everything looks OK, you need to reset the gas system:
- Have someone in the counting house push and hold the reset button; if you have enough minutes on your cell plan, stay in contact with them.
- Flow should start on both channels.
- Watch the pressure; the system run a PID loop on 500 Torr. Initially, the system will overshoot. Once it's coming down again, the person in the CH should be able to lift their finger off the reset button. Expect this to take a few minutes. Eventually, the system should stabalize.
- In case their has been an extended stop of flow, wait for some time before turning on HV again (need to specify further)
2. Red "LOW PSI" indicator light and HMS AIR FLOW or HMS TEMP red and really annoying sound
In the past, this has been an indication that "clean power" has tripped. This needs to get resolved before above recovery procedure will work.