Forward Pixel Cooling System Information

1. Forward Pixel Cooling System Information Joe Howell CMS Pixel Technical Board Meeting – Dec. 16, 2005

2. Sources of Information • Presentation document by Paola Tropea • Engineer CERN TS/CV Department • CMS Tracker Cooling system overview presentation Dec 03, copy captured in docdb #590 • Very good overview of the entire CMS Tracker cooling system • Invitation to Tender IT-3230/TS/CMS for cooling system • Technical Specification for design, construction and installation of a double loop fluorocarbon 150 kW cooling plant for the CMS Tracker and Preshower detectors • From CERN EDMS document system • One of many related documents, yet to review others • Meeting with Scott Reeves and reference information Scott provided • Fermilab AD engineer responsible for Fluorinert cooling systems • Notes and much reference information captured in docdb # 571 • Meeting with CMS Tracker engineers during Dec 05 CMS week • Paolo Petagna,  Hans Postema • My notes and others to be captured in docdb # 623 • Presentation material and notes from meeting with Kurt Gabathuler, PSI • The contact person for barrel mechanics • Very familiar with forward pixel • Lots of information mining still remains to be done CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

3. Overall system diagram “These units must operate continuously, even in case of power or water cut, and they will be cooled by an emergency refrigerator, using the available Emergency Power Supply (EPS, provided by CERN).” CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

4. Location of pixel cooling rack CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

5. Specifications provided by Kurt Gabathuler, PSI Forward Pressure map similar to this Barrel version CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

6. Pixel secondary system diagram CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

7. Hydraulic symbols CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

8. Details of secondary system branches Pixel Detector CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

9. Pixel secondary system notes • 4 branches for +Z side and 4 branches for –Z side • Each branch has: • a manual throttle valve to set flow • Pneumatic shutoff valve at inlet and outlet • A calibrated orifice plate • Schrader (self sealing quick disconnect) valve on each side of orifice on supply side which could be instrumented to measure flow • Schrader valve on return side • Reservoir tank is instrumented with a strain gage balance to measure weight change for leak detection • The CERN engineers described a system to perform a leak check on each branch by isolating each branch with the pneumatic valves and then monitoring for a pressure drop/rise. (I have not seen a PID diagram for these elements yet) • My understanding of the CERN engineer’s philosophy for leak detection/action is: If you have a small leak that is not detectable with the reservoir balance you would not stop running even if you knew it existed. If the leak is large enough to be detected with the balance you would then proceed to leak check each branch and then leave that branch turned off if necessary. CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

10. Notes from discussions with CERN engineers • They are well aware of Fluorinert/elastomer compatibility issues • Fluorinert decomposition • Charcoal filters were tested and shown to remove Fluorine ions • Paola Tropea’s presentation lists Alumina filters for acid removal • Cleaning and material selection to remove hydrogen sources was emphasized • Discussed continuous chemical monitoring vs periodic sampling • They requested a concise description of conditions that caused problems in Fluorinert system at Fermilab • CERN engineers expressed concern with long term integrity of fluid connections • Seemed less confident of radiation resistance of epoxy used at blade connection points • Also suggested metal connection instead of silicon tubing • They were interested in 3M document that gave guidance on how to seal fluid connections. I got the impression they have struggled with leaks in an existing system. • Thermal screen is intended to maintain un-powered silicon cold in the event of a power outage or primary system failure • Sniffer lines for smoke detection in tracker volume • Supply and return lines are copper and there is some experience with copper/aluminum compatibility during tests of the thermal screen CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell

11. Miscellaneous notes • Experience with a radiation induced Fluorinert decomposition in Fermilab AD led to extensive investigation • Information exchange with 3M and others • Special filter developed by 3M is used in all applications • My impression is that every novice user of Fluorinert has problems with leaks and leak detection • Notes from discussion with Jeff Spalding about integration area infrastructure • C6F14 Plant capable of delivering +10 C (uses +6 C chilled water CERN standard) • Could be upgraded to run colder • Interlock system (one to share with Pixel and Barrel) 16 temp, 8 humidity, 8 outputs • Could be loaned when available CMS Forward Pixel Technical Board Meeting – Dec. 16, 2005 Cooling System Information – Joe Howell