1.　　SCOPE OF WORK

This section sets out the design, fabrication, supply, deliver, installation, test and commission of the gas distribution system. The gas distribution system shall cover from the gas outlets on the benches or fume hoods to gas regulator manifolds at the cylinder area.

There are six types of gases in CCIQ laboratory and the main include the following

a	Argon (Ar)	氩气
b	Helium (He)	氦气
c	Oxygen (O2)	氧气
d	Compress Air (CA)	压缩空气
e	Acetylene (C2H2)	乙炔气
f	Nitrous oxide (N2O)	一氧化二氮气

2.　　BRIEF DESCRIPTION OF PROPOSED GAS DISTRIBUTION SYSTEM
Laboratory gases shall be piped into the laboratory work area from a gas yard outside of the laboratory. All gases shall be supplied from Pressurized Gas Cylinders except for plant/instrument air that is supplied from the production facilities. There shall be semi-auto change over system in the gas yard and main pressure valve and relief valves should be located outside the lab building. The gas pipe, made of stainless steel, shall be led into lab by running below ceiling or along the wall so that all gas pipes should be easily checked and maintained. In addition, pipe shall be delivered to island benches via service columns. All point of use shall have suitable valves and fittings within easy reach. All gas line joints shall be orbital welded except those connecting to valves.

3.　　GENERAL REQUIREMENT

　　For Compress air going into chemical analysis area, the supply shall be backed up by at least 2 cylinders of compressed air. The line shall be connected via a flange and the pipe leading into the labs shall be stainless steel. A filter for particulate and water shall be used at this point preventing particulates and heavy moisture from getting into the laboratories. This filter shall be installed with proper isolation valves so that operation would not be affected when there is a need to perform regular maintenance on the filter.
　　The following describes the gas piping system intended for chemical analysis area.

4.　　CYLINDER MANIFOLD AND REGULATORS

4.1.　　Each gas manifold shall be constructed to provide semi-automatic switch over from in-use cylinders to online backup cylinders.

4.2.　　All gas plumbing for manifolds shall be constructed from high quality, fully annealed seamless type stainless steel SS-316L. Gas pipes used for O2 gas lines must be specifically cleaned and suitable for use with O2 in order to prevent accidents.

4.3.　　Manifold shall have safety pressure relieve valve, pressure regulators, and pressure gauges indicating inlet and outlet pressure, bleed valve (vent valve) and pigtail for cylinder connections.

4.4.　　All relieve & purge valve shall be connected by a vent line leading away from the gas storage area. Vent lines for combustible/oxidizing gases shall not be grouped together.

4.5.　　Pigtail shall be flexible type (made by stainless steel tubing)

4.6.　　Safety relief valves shall be labeled for relief pressure rating.

4.7.　　All valves, regulators and gauges proposed shall be of good quality, stainless steel type, made for specific gasses and shall be provided with standard fittings.

4.8.　　All regulators shall be stainless steel diaphragm type. Regulator with heat sink shall be used for N2O cylinders. Full stainless steel regulators shall be used for gases that contain sulfur. Fittings and valves shall be from Swagelock or equivalent.

4.9.　　A flashback arrester of approved type shall be included in the Manifold for Hydrogen

4.10.　　All manifolds shall be labeled with names of gasses it supplies.

4.11.　　All labeling shall withstand local weather.

4.12.　　Secured holders shall be installed to hold all gas cylinders. All gas pipes shall also be properly grounded for safety reason.