3.1.3
GAS SUPPLY, GAS SYSTEMS AND PIPES (WILL BE REWRITTEN BY ROBERTO)
The gas supplies system will be installed outside the GIF++ building in two separate rooms: one for
neutral gases (Ar, CO2, N2, He, SF6, CF4) and one for flammable gases or gases with very low vapour
pressure (iC4H10, CH4, Ar/H2, CF4, C2H2F4, nC5H10). The latter will be heated in order to ensure
enough pressure at the input of gas systems and it will also contains several zones classified as zone
2 and therefore instrumented with ATEX certified equipment. All gases will be connected to
automatic change-over panels based on pressure measurement. If possible, for gases that are liquid
at ambient temperature, the change-over mechanism will be based on weight otherwise the
modification will be implemented in a second phase. One line for each gas will be installed from the
gas supply zone up to the GIF++ service area. The pipes for gases with low vapour pressure will be
heated (iC4H10, C2H2F4, …). Several panels will be available for the primary gas distribution to all
mixers and analysis devices. The consumption of all gases will be monitored at the mixer level.
The gas systems will be built following the standard used for the LHC experiments. All system will be
running on one dedicated PLC. PVSS is used as software for the control interface. Data about gas
systems status and important values will be also available on the network.
At least three gas mixers will be built and ready for the first operational phase of the GIF++ facility.
They will be designed in order to accommodate as much as possible the requests from all the users.
The gas re-circulation rack from the old GIF facility will be verified and used for the cosmic trigger
setup. In a second phase, other two or three gas recirculation rack will be built in order to satisfy the
different detector groups.
Since flammable gases will be used, a flammable gas detection system will be installed. As usual,
detection point will be located near the primary gas supply panels, in the mixers using flammable gas
and inside the facility. The flammable gas leak alarm will be propagated to the CCC and Fire-brigade
using the standard procedure. The concentration of a flammable gas in the gas mixture will be
monitored using infrared analysers.
One analysis rack with O2 and H2O analysers will be available and it is intended to be used for all the
gas systems. An automatic system will scan all the selected lines. After a first period of
commissioning, a gas chromatograph will be also included in the gas analysis rack.
Several gas distribution panels will be available in the preparation zone and inside the facility
(typically about 3 in the preparation zone and 5 in the irradiation area). Each panel is sub-divided in
two parts: one for lines that do not contain flammable gases and lines that might contain flammable
gases.