3.4
NONMEDICAL (NON-OIL-FREE) COMPRESSED AIR PIPING
Nonmedical (non-oil-free) compressed air piping shall be installed as
specified for water piping and shall be suitable for 862 kPa 125 psig
working pressure. Air piping shall have supply lines and discharge
terminals legibly and permanently marked at both ends with the name of the
system and the direction of flow.
3.5
MEDICAL (OIL-FREE) COMPRESSED AIR AND VACUUM PIPING
Medical (oil-free) compressed air and vacuum piping shall be installed as
follows. Medical compressed air and vacuum piping shall be cleaned,
tested, and installed as specified in NFPA 99. Piping shall be connected
near the top of the receiver. Vacuum pump exhaust pipe shall be extended
to the outside of the building and its end turned down and screened against
insects. A dry nitrogen gas or other approved inert gas purge may be
provided to prevent oxide formation inside the copper tubing when silver
brazing joints. Compressed air and vacuum system alarms shall be located
as specified in paragraph ALARM PANELS FOR MEDICAL GAS AND VACUUM SYSTEMS.
Joints shall be made with silver brazing alloy, except at valves or
equipment requiring threaded pipe connections. Pipe threads on shutoff
valves shall be installed by tinning the male threads with soft solder.
The medical compressed air piping and vacuum system piping shall be
suitable for 862 kPa 125 psig working pressure. Where oil-free air is
required in laboratories, the piping system shall be separate from the
medical surgical system. Vacuum at 51 kPa 15 inches of mercury shall be
provided at operating rooms, delivery rooms, and patient's clinics.
Pipelines shall be readily identified by appropriate system labeling at
intervals of not more than 6 meters 20 feet and with at least one such
identification in each room. Antivibration couplings shall be installed
between the vacuum pump and the pipeline and between the vacuum pump and
the exhaust pipe. Initial startup of the oil-free compressed air system
shall be under the supervision of system's manufacturer.
3.6
NITROUS OXIDE, OXYGEN, AND NITROGEN SYSTEMS
A dry nitrogen gas or other approved inert gas purge shall be provided to
prevent oxide formation inside the copper tubing when joints are silver
brazed. Piping inside of building and aboveground shall be hard-drawn
copper tubing and piping underground shall be annealed. Underground piping
shall be adequately protected against frost, corrosion, and physical damage
by nonmetallic ducts or casings. Fittings used for joining copper tubing
shall be wrought copper or bronze, made especially for soldered or brazed
connection. Joints, except those at valves or equipment requiring screw
connections, shall be made with silver brazing alloy or a similar high
melting point alloy of not lower than 538 degrees C 1000 degrees F. Screw
joints used in shutoff valves, excluding station-outlet valves, shall be
installed by tinning the male thread with soft solder.
3.7
JOINTS
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NOTE: Where environmental conditions do not warrant
the use of dielectric unions or flanges the
requirement for such unions and flanges will be
deleted.
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Installation of pipe and fittings shall be made in accordance with the
SECTION 15405A
Page 83
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