3 The issue Performance worsening in time Minimum acceptance reached: 62.5%, most because of cooling failureStart of LS1 <45%extrapolation from last yearassumes constant trend
4 Critical components X T D Capillaries (CuNi, 550 mm long, 0.5 mm i.d.) Cooling pipesPhynox, 40 μm wall thicknessRound 2.8 mm pipes squeezed to 0.6 mm inner sizeInline filtersFundamental to protect previous items, 60 μm porosity1 accessible during beam stop1 accessible dismantling part of ALICE (~6 months job)(Missing) filter at the plantadded after 1 year run a 2 μm filter at the liquid outletSEM picture of the filter(orange square=1mm2)no accessPP=patch panelXTD = mmT = mmX = 0.7 mm (~1 mm in the filtering area)D
5 poor cooling performance & local inefficiencies Chase the guiltySearch and confirm the cause has been a long and painful process, 4 years longAll procedure tested on a dedicated test bench set up by our team with CERNMany tests performedSEM analysis of PP4 filters enlightening…many particles of several materials, possible origin:graphite from pumps, weldings, plant’s hydrofilter20 μmThe filters mesh has 60 μm size in averagesmaller sized particles can be stopped and bigger can go through!some pollution can pass the first filter and stop on the secondOnce clogged, the second (PP3, not reachable) filter causes:pressure droplower flow rateAdd the heat-up of the fluid along the supply line, and you have:poor cooling performance & local inefficiencies
6 The hard way: drilling TESTED BY DRILLING > 100 FILTERS ! After several (unsuccesful) attempts (solvents, ultrasounds) we went ‘’the hard way’’ with the following procedure:drilling:tungsten carbide tip welded on 5 m long twisted ss cable, rotated by a drillcounter-flow at 200 mbar w/manometer to detect the presence of the hole (~50 mbar drop)takes 2-3’cleaning:rilsan pipe connected to a rotary vane vacuum pump to aspire the drilling debriswalk inside the pipe with a twisted ss cable with a magnetic tip fixed at the endcleaning machine to force counter-flow wise a cleaning fluidrepeat several times the previous stepslast, let the cleaning machine run overnight (or more) with a 60 m filter to collect particlesanalyze this filter with an optical microscope and (if needed) the SEMredo the cleaning procedure if not happyTESTED BY DRILLING > 100 FILTERS !
7 Access point Target point Fiberscope L=5 m, Ø=1.5 mm magnet Edwards RV3 rotary vane 2-stage pumpFiberscopeL=5 m, Ø=1.5 mmmagnettungsten carbide 5-faces tipcleaning machineAccess pointØ 2.5 mm ss twisted cableTarget point4.5 m of ss pipe 4mm i.d.
8 The drill team Yannick Lesenechal Andrea Francescon Samuel Rambaut Claudio BortolinRosario TurrisiRoyal straight: five nice cards but the strength is the team!And we’re well backed by the whole SPD team!
10 Clean it! Sector #9 drilled on Feb 14 Material collected by vacuum cleaning after drillingMaterial collected afterthe cleaning procedureAnalyses by Norberto Jimenez Mena and Maud Scheubel (EN-MME-MM)
11 Materials analyses stainless steel silicon compounds (a.k.a. ‘’dust’’…)fluorine compounds100 μm100 μm100 μmAnalyses by Norberto Jimenez Mena and Maud Scheubel (EN-MME-MM)
12 Interventions and results Drilled 5 filters: sectors 9 (Feb 14), 7 (Feb 27), 6 (Mar 6), 4 & 5 (TS Apr 23-27)Oldest flow rate values from last November8 sectors above nominal value5 drilled, 3 because of vacuum cleaningLast cleaning of sector 3 restored the possibility to turn it on completely!121211hs on111110121211101.8 g/s = nominal valuenew flow rate valuesold flow rate valuesdrilled filters
13 snapshot from November 10, 2011 Recovered acceptanceAcceptance changed from this…to this!65/120 modules ‘’on’’ %snapshot from November 10, 2011112/120 modules ‘’on’’ %NOW RUNNINGcannot be recoveredcould be recoveredhot100% cooling efficiency !!!
14 Happy end! Recovered the cooling system to 100% efficiency no more ‘’special maintenance’’ until pPb run (unless needed)The plan for LS1 changed accordingly: no need to move TPC, ITS, etc. (>6 months job!)If needed could do the drilling of the 5 left filtersFinally our soundtrack plays!…and the SPDer’s
15 Attività SPD @ CERN TS3 (17-21 Settembre 2012) Test in pressione delle vecchie linee di input (2 pp x 4gg)Durante LS1 (11 Febbraio 2013 – xx/xx/2014)Rimozione nuove linee input e subcooling (4 pp x 5gg)Ripristino vecchie linee (pulizia, connessioni, leak test) (4 pp x 10gg)Consolidamento rack impianto (CERN EN/CV/DC)Installazione filtro acqua (CERN EN/CV/DC)Ricalibrazione valvole sicurezza (CERN EN/CV/DC)Ricalibrazione sensori temperatura e pressione (2pp x 5gg)Foratura filtri di 5 settori (dipendente da andamento prestazioni, 1ppx15gg +pers. CERN)
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