Measurements of properties of four parallel Al staves operated in under pressure mode

Talk presented at the special CERN workshop on ATLAS mechanics, 26 February 1997

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C. Caso & F. Gastaldo/INFN-Genova

V. Vacek/CTU Prague


    CPPM Al staves (used at RAL)
    our exp. set up consists of:
      operations in a cold isolated box with He flux
      8 Pt100 on "silicon side" (two per stave: input and output)
      20 AD590 temperature sensors (5 per stave: two on "silicon side" and three on the cooling tube side) unused in this run
      12 differential gauge pressure sensor (RS) across the staves (three per stave)
      1 overall differential gauge pressure across the manifolds
      2 (absolute) pressure sensors across the cold box
      1 volumetric flow meter (uncertainty ±2%)
      2 Pt100 INSIDE the cooling tube (input/output: ice conc.)
      8 180 Ohm MINCO heaters (two per stave simulating the nominal 80 W pixel sensor heating) powered in parallel
    some modifications to the frame/manifolds were necessary to fit the apparatus into the cold box
The under pressure/over pressure mode is obtained via the system pump operational mode (clockwise/anticlockwise rotation: sucking/pushing)


1 2 3

One and half day of data taking.
VERY STABLE RUNNING CONDITIONS
Absolute ice concentration = 8%
No power
Overall flow = 68 l/h (18.9 cc/s)

Pressure profile (p2 is across the stave)

Stave #1 #2 #3 #4
p1 (mbar) -331.4 -343.5 -330.4 -338.0
p2 (mbar) -184.3 -192.6 -197.4 -185.7
p3 (mbar) -218.8 -205.3 -219.4 -213.9
p (mbar) -734.5 -741.4 -747.2 -737.6
p (manifolds) = -826.6 mbar
Pinput = -70 mbar Poutput = -980 mbar
p (box) = -910 mbar
Tinput = -17.6 °C Toutput = -17.0 °C

CLOSE STAVE # 3


Flow = 52.8 l/h (expected 51 l/h)
Stave #1 #2 #4
p (mbar) -758.6 -767.9 -761.3
p +3.3 % +3.6 % +3.2 %
p (manifolds) = -854.5 mbar (+3.4 %)

CLOSE STAVES # 1 AND #3


Flow = 37.6 l/h (expected 35.2 l/h)
Stave #2 #4
p (mbar) -795.1 -790.3
p +7.2 % +7.1 %
p (manifolds) = -883.5 mbar (+6.9 %)

POWER ON
ALL 4 STAVES OPEN


40 W on stave # 1 (power supply has 60 V max)
flow = 68 l/h

Pressure profile (p2 is across the stave)

Stave #1
p1 (mbar) -350.7
p2 (mbar) -177.8
p3 (mbar) -206.1
p (mbar) -734.6

It takes horribly long time (~ 1 h) to get stabilised when heated!!