1. TK Dry Gas System Operation  System overview  Dry Gas Consumption  Interlocks and thresholds  Documentation  Operational model  Final comments

2. Gas sources N2 dewar –110 Nm3/hr max. 3 x air compressors @ 6 bar –1 x 39 Nm3/hr –2 x 50Nm3/hr Back-up bottles (only for the ‘cold’ systems) –4 x 120 m3 –Pressure reduced at surface from 200 to 7 bar –Pressure relief valve @ 12 bar

3. Tracker N2 system Filters – particulate + oil Parallel dew point meters (interlock) DT1 pressure + flow monitoring (DIP) ECAL ES From N2 dewar Extra flow meter on line to TK for interlock

4. Tracker N2 + air system Can select line for DP monitoring Air / N2 master switch Pneumatic valves with state transmitters Electro-Pneumatic valves for interlock Switch-over panel From bottles From compressors

5. TK, ECAL + HCAL Small dryer for ECAL / HCAL

6. Sub-detectorMax. flow (Nm 3 /hr) TK internal volume32.0 TK PP1 boxes24.0 ECAL ES9.6 ECAL EE3.8 ECAL EB14.4 HCAL HF2.4 HCAL HE-HB-HO11.5 N 2 Total 97.7 Cooling Boxes (Dry Air only) 7 Sub-detectorFlow (Nl/hr) Pressure (mbar) Gas TK internal volume17006600N2N2 TK PP1 boxes17344550N2N2 ECAL ES2138100N2N2 ECAL EE3286420N2N2 ECAL EB109301250N2N2 HCAL HF17841000N2N2 HCAL HE-HB-HO92081550N2N2 N 2 Total61696 SS1 Cooling Box120005000Dry Air SS2 Cooling Box120005000Dry Air Pixel Coolong Box48005000Dry Air TS1 Cooling Box12005000Dry Air TS2 Cooling Box12005000Dry Air PS1 Cooling Box48005000Dry Air PS2 Cooling Box48005000Dry Air Cooling Boxes (Dry Air only) 40800 Consumption Design Max. flows Present consumption 15/04/10

7. Interlocks and Thresholds Requested Interlock Logic. All the hardware to implement it is there. Machi’ s talk for details. Switch From ToIfValueAction N2N2 Dry AirN 2 Pressure < 2 bargAutomati c N2N2 Dry AirN 2 Dew point > -45 o CForced N2N2 Dry AirN 2 Flow< 12 Nm 3 /h Forced Dry AirBottlesDry Air Pressure < 3 bargAutomati c Dry AirBottlesDry Air Dew Point > -15 o CForced Dry AirBottlesDry Air Flow < 12 Nm 3 /h Forced Thresholds table

8. Documentation The CMS Inertion and Flushing System : Technical Guide –Functionality –Interlocks and monitoring –Failure scenarios and recovery procedures –System maintenance –Contact persons –Filter specifications –Spare parts list –Hyperlinks to Schematics, dryer manuals, pipes distribution, switch over panel pneumatic layout. Mass flowmeters calibrations Rotameters calibrations Instrumentation documentation To be stored in a better place than my hard drive.

9. Operational model so far…… No CMS Dry gas system maintenance crew. Operation and maintenance based on the “good will” system. Overall Experts: Stefano Moccia, Nick Lumb. Distribution gas racks experts: PH-DT (Andrea D’ Auria, Roberto Guida, Albin Wasem). Monitoring: –PH-DT for the distribution racks (pressures and flows to all the subdetectors). Info available via DIP. –TK (flow to the TK volume, valves state, switch over panel, Dew points). A good number of people in the TK community has helped to run the system. Occasional interventions for small upgrades, dryer maintenance and tests. This model has survived so far because the system is quite stable and has not given major problems. Need to transfer responsibility to PH-DT in order to centralize the operations and maintenance especially if we are going towards colder running conditions for cooling Need to mesh the two monitoring systems Need to add some more parmeters to the monitoring (i.e. bottles supply pressure, driers state…..).

10. Dry Gas system summary At the present CMS is flushed with N2 (about 62 Nm3/hour) which is the default state for the dry gas system during operations. The N2 provides the CMS inertion and necessary dryness inside the Vac Tank. The N2 system has proven to be quite stable and reliable. The Dry Air system is the backup for N2, but, of course, provides only the dryness. The only “normal” failure modes for N2 and Dry Air systems are low pressure or high humidity. Tests have proven that the system reacts properly. Power cuts are taken care (supposedly) by UPS and Diesel. It has never been fully tested. TC has determined that if there is a switch to Dry Air due to some failure of the N2 system, there is a max waiting time of 1 hour to have the N2 back otherwise the detectors inside the VacTank need to power off. Better operational model to setup. Some worries for the Dry Air system as a backup for the N2: –The flushing and the instrument air share the same source (4 compressors for about 139 Nm3/hour). –If there is a switch to Dry Air (N2 problems shutdown configuration with CMS open), with the present consumption, the compressors won’ t be able to keep up with the demand for long. –This could cause a possible failure of the instrument air system causing systems shutdown. –This problem will become more evident in the future when Tracker and Preshower will run at way below subzero temperatures. –Decouple the instrument air from the CMS flushing is recommended along with larger dry air source. – Reduce drastically the consumption for the cooling boxes by improving the sealing, switching to N2…….