sPHENIX discussion of the superconducting solenoid

[Kin Yip <kinyip AT bnl.gov>]

Hi Ray,

Can you please come to Bldg. 911 to talk with Mel so that you guys can write a work permit ?   Maybe, you can bring me --- the middle-man here --- along.

I think Mel is not happy that you guys don't have a written procedure for using HD ?   ( What if the cylinder of HD leaks in 912  ... ? )
The best that I can do is get you to talk with Mel and write a work permit ...

Kin

On 10/12/2015 01:50 PM, Ceruti, Raymond B wrote:

Leak test of SPhenix valve box.

    

      After first failing a pressure leak test we opened the vacuum vessel, pressurized the helium system with about 25 PSI and used the sniffer feature of a helium leak detector.  In short order we discovered a cryogenic break leaking at about the three scale level.  We proceeded to replace this break with a new ceramic one.

 

     After closing off the vacuum vessel, pumping down and charging the helium system there seemed to be about a five scale leak still present.

 

      We then decided to pump a vacuum on the helium system itself.  This idea could work if the system would clean up enough (remove enough helium contamination) so as a leak detector using helium would become sensitive enough.  After almost a week of pumping we were able to get the leak detector to about a 7 scale.  With that we found another leak in an elbow between the leads.  We soft soldered this joint and that leak appears to be fixed.

 

     Another attempt to perform a pressure leak test showed about a 6 scale leak(s) still existed.  We decided to open the vacuum vessel again, bag off two other cryogenic breaks as well as lower plumbing with numerous fittings, also the previously repaired elbow joint and related tubing.  This was left under 50 PSI of helium over the weekend in the hope that if any of these components were leaking, helium would accumulate enough to be detected……………………..  Monday morning, (10/12) we didn’t detect any helium leakage in any of our bagged components.

 

What to do next:

    For the next test, we would like to put the inner helium system under vacuum and bring in a different leak detector that is capable of detecting HD.  The procedure would involve spraying a very small amount of HD on joints and suspect areas in the hope of detecting a leak(s) that still exist.  We would need to bring in a K size cylinder of HD, regulate it down to about five PSI, using a needle valve and 1/8 “ size tubing attached to a hose, spray very small amounts of HD on suspect areas in hope that we find this “needle in a haystack” leak(s).   

 

Regards,

Ray