1. ID week 27 th of April 15 C3F8 cooling- Compressors & C3F8 status O. Crespo-Lopez EN/CV

2. Current status Run conditions: – Leak rate: 1.72 kg/day – All loops open – Pressure stability in the racks: ok no drop since the start – Air compressed: 46 compressor start-up in 24h (leak to be checked)

3. Compressors compressorhoursstatus Next maintenance Maintenance type remark 129213Not runningIn 2.500 h2.500 h 226815Not runningIn 2.000 h2.500 h 326550RunningIn 1.000 h5.000 hTo be done in June 425693RunningIn 1.600 h5.000 hTo be done in July 515009Not runningIn 1.700 h5.000 h 610740RunningIn 800 h2.500 hTo be done in June 79140Running (master) In 1.000 h10.000 hTo be done in June with Haug (3 days of work) Compressors maintenance: 2.500 h (≈3 months of run): replacement of the outlet filter 5.000 h: replacement of the 2 nd stage O-rings + outlet filter 10.000 h: big maintenance with replacement of all the mechanical parts

4. Cooling plant in general Action list for the next technical stop without stop of the plant: Preventive Maintenance – Maintenance on the compressors 3-4-6 & 7, these ones will be stopped one by one for (WARNING: during the swap of the compressor 7 master there is a risk to stop the plant) – Filling of the plant – Replacement of the liquid filters – Leak search in the racks in UX15 (side compressed air and C3F8) Specific corrective maintenance – Replacement of the electrovalves to drain the water on the air compressors Fluid – C 3 F 8 stock @ CERN: 3.500 kg – New order on going (fluid @ CERN on June) – New 5 years contract for September 2015

5. specific point Liquid condenser – During the re-commissioning of the plant it has been observed that the condenser was not able to fully condense and to sub-cool the C 3 F 8. – New problem on the condenser? Clogging? Apparently during the last LHC run in 2012 the system was already running in these conditions. – Currently to be able to condensate and maintain the pressure @ 15 bars we need some mixed water flow inside the subcooler of the tank. – This situation is clearly not a problem for the operation of the plant but we are looking for a new condenser in view to have the good material Proposal – We are waiting several offers from suppliers – As soon as we will find the good material we will circulate an Engineering Change Request for acceptance – Once the new condenser @ CERN we will prepare this one to be ready for replacement ASAP – The best way will be to replace this one during Christmas shutdown to be able to fully test the new behavior.