The Australian Standard AS2896-1998 states
Materials;
Copper tubing used in medical gas piping systems shall be "drawn" seamless tubing manufactured in accordance with AS/NZS 1571.
Copper fittings shall conform to ASME B 16.22.
All components of the piping shall be oxygen compatible and shall be clean and free of grease and particulate matter.
Components include vessels, piping, lubricants, fittings, gaskets, etc.
Compatibility includes flammability and combustibility. Materials that burn in air will burn vigorously in pure oxygen.
Maintenance and cleaning of tubing and components;
GNEE medical gas tubing is factory cleaned, degreased and capped in accordance with AS/NZS 1571. Tubes must not be cleaned on site except for necessary cleaning operations to remove particles entrained during installation.
GNEE fittings are delivered clean and shall be protected from contamination during transportation to the site.
All medical gas tubing and fittings shall be stored and handled with extreme care. After cutting, tubing should be temporarily capped or plugged to prevent contamination prior to final assembly.
Radial pipe cutters that do not produce chips or filings should be used when cutting existing systems.
Design Requirements for Medical Gas Piping
Piping and fitting sizes should be selected to provide the design flow required throughout the medical facility.
The nominal design working pressure shall be 415 kPa for medical gas supply, -60 kPa for medical suction, and 1400 kPa for surgical tool gas supply.
Flow requirements should be determined based on discussions with the medical facility to determine the expected and projected gas usage and the amount of terminal equipment required.
All medical gas piping systems shall be designed, fabricated, installed and inspected in accordance with AS 4041.
Piping Protection;
Piping in exposed areas shall be protected from physical damage.
Buried piping shall be adequately protected from frost, corrosion and physical damage.
Copper pipes may be severely corroded if buried in direct contact with certain corrosive environments.
GNEE jacketing can be used to protect copper tubing in sizes 12.##7mm (1/2") and 19.##05 (3/4").
Medical gas piping may be placed in the same tunnels, trenches, or ducts as fuel gas piping or steam piping, provided that such medical gas piping is at least 50 mm away from other services and is well ventilated.
Medical gas piping shall not be
Be installed in tunnels where they may come into contact with oil.
be installed in or through any ventilation ducts, clothing chutes, elevator shafts, waste chutes or ventilation ducts.
It is not recommended that medical gas piping be poured into reinforced concrete or installed under ground floor slabs.
Where piping passes through masonry walls, partitions or floors, the piping should be fitted with a protective sleeve, known as an MM GNEE sheath.
Non-flux brazing technology
All joints (copper pipes and fittings) shall be brazed.
All brazing alloys used in the manufacture of pipes and fittings shall conform to the B4 alloy designation as specified in AS 1167.1.
Fluxes shall not be used in the field. For off-site applications, only water-based fluxes may be used.
Commercial grade carbon dioxide shall be used as an internal inert gas shield during brazing operations.
Fluxless technology with an inert atmosphere prevents contamination of the inside of the pipe with flux residues and oxidation scale and minimizes the risk of fire from brazing.
After the work is completed, a purge is required and the particulate matter and carbon dioxide levels are tested.
