Kyle, Gerardo, Chandra 

Today we pumped IP11 using a local turbo backed by an aux. cart.  IP11 is isolated from the Y-end via its closed GV.  As I squirted IPA around each CFF joint and vacuum welds of the Chevron Baffle nipple, Gerardo M. monitored the pressure gauge on the aux. cart to see if there was a response.  Chandra R. had already established this to be a very large leak (0.1 torr*L/sec).  We tried "listening" for the audio leak using a device intended for that purpose -> Something seems to be originating from the Chevron Baffle but difficult to eliminate background noise in the room -> We shut down the Clean Room (1417 hrs. local) and that helped a little.  Next, we modified the as-found bag such that each CFF joint was exposed but keeping the nipple's tube vacuum welds within the bagged volume.  We then purged the bag with bottled N2 while spraying helium around each CFF joint -> no significant response.  Finally, we reversed the bagging, now purging the CFF joint(s) while spraying helium around the welds of the nipple tube -> found very large leak coming from the bottom tube-to-flange vacuum weld (nipple s/n 01).  

Having found one leaking Chevron Baffle, Chandra R. examined a different one stored in the VPW.  She found suspicious looking welds.  

Also, we prepared IP11+chevron baffle nipple for tomorrow's removal by venting it with bottled UHP N2 and removing all but (3) ea. of the nipple-to-GV nuts and studs.  Note that with the local turbo spun down and disconnected from the aux. cart, I applied the N2 to the Tee at the inlet of the turbo letting it flow trough the turbo and into the room via the open-ended turbo exhaust line.  This setup would prevent the possibility of over-pressurizing IP11 as it remained open to the room.  I then opened the 1 1/2" vent/pump valve to vent IP11.  Gerardo M. noticed that room air was then entering through the exhaust.  Thus, for a short period, I had been back streaming through the local turbo and into IP11.  I then closed the 1 1/2" valve and removed the turbo. This is a "dirty" pump in that it is not a maglev.  I'll consult Chandra R. as to what, if any action is needed (FTIR?).