Compressed / dry air

Overview

• Dry air must be flushed in the detector SiPM cold boxes and inside the cooling manifold to avoid condensation/frost.
• According to the specification https://edms.cern.ch/document/335007/1.0, the compressed air distributed in the LHC tunnel is good for this application. The dew point is -40 C.
• An outlet of the compressed air distribution line was installed next to the BGV (Jan 2015)
• The air distribution chain was installed and put into exploitation in September 2015 (TS2)

Air distribution chain

• The BGV air distribution system was developed together with EN-CV
• The layout was designed and the system components were chosen together with Francisco Josa (EN-CV-DOW)
• The functional specification are given in separate section below

Documentation

• All components are from FESTO. The order, made by Francisco, can be seen here
• Purchase order on EDH: https://edh.cern.ch/Document/SupplyChain/DAI/6037894
• Tubes and fittings
  • Tubes connecting the detector modules to the manifold: PUN-H-6X1-SW from FESTO (OD/ID=6/4 mm), non-transparent (e.g. black)
  • Fittings on the detector modules: QS-6 ("Union QS") from FESTO, used instead of the initially planned NPQP-D-Q6-E which are transparent

Layout

Components from left to right:       ? Manually operated on-off valve with       silencer (type MS6-EM1)       ? Filter (type MS6-LF)       ? Pressure regulator (type MS6-LRP)       ? Flowmeter (type SFAB)       ? Manifold pdf file step file

Tunnel photos

The mapping between the Air manifold valves and the Detector modules is given in the Section "Operational aspects" below.

Functional specification

• This document discusses the requirements (e.g. the needed flow of air)
• Initially considered layout:
  
• The air inputs of the detector modules and manifold are shown in the models below
  • The detector drawing below is outdated -- in practice there is no serial connection between modules, meaning that each module has 2 independent supply lines
• The direction of flow is important. For details, see the document above.
  

Operational aspects

• As discussed in the document above, the needed air flow is:
  • 20 l/hour = 0.33 l/min per SiPM array (i.e. half module)
  • 400 l/hour = 7 l/min for the cooling manifold
  • 720 l/hour = 12 l/min in total (16*20 + 400 l/hour)
• 20+1 individual valves allow to adjust the flow through each output of the air manifold
• The total flow going out of the manifold can be adjusted by rotating the cylinder located at the bottom of the pressure regulator (the third element on the plate)

• Flow settings 14-10-2015 (Bernd)
  • Total flow: 30 l/min
  • Flow into cooling manifold: ~10 l/min (two tubes)
  • Flow for all 16 SiPM arrays: ~20 l/min (test done opening only one valve at the same time: about 1 l/min)

• Mapping between the Air manifold valves and the Detector modules
  • Valve - module mapping

Flowmeter interlock and wiring

Interlock for the cooling chiller

• The user manual of the air flowmeter provides detailed and clear instructions how to configure the flowmeter switch/TOR outputs
• Current settings (Sept 2015):
  • Using digital output A
  • Switch setting: NO (normally open)
  • Switching Threshold: 10 l/min, Hysteresis: 5 l/min. In practical terms:
    • Increasing the flow from 0 l/min, the interlock will switch-on when the flow goes above 10 l/min
    • Then, if the flow goes down, the interlock will switch-off when the flow goes below 5 l/min (i.e. below Threshold - Hysteresis)

Cabling and wiring schemes

• Cabling chain for the air flowmeter and the chiller PT100 probe
  • Info about the cables used and the nodes along the chain
• Wiring for the flowmeter
  • Info about the wires used to provide 24 V to the flowmeter and the acquisition of the interlock signal
• Connector wiring
  • Info about the junction box used to transit from a 5-pole connector to an RJ45 connector