area is tested for leaks with soapy water and the leaks, if
any, are repaired.
I.
After all leaks, if any, are repaired and the line is fully
recharged, blowdown and testing are performed. The zone closet
to the main is opened to the system, the closest outlet to the
work is accessed, and the main blown through the outlet. After
the outlet blows clear into a white cloth, and oxygen analyzer
is used to determine that only oxygen is present. An
additional check is made at a zone most distant from the site
of the work.
J.
The use of shaped memory alloy couplings is recommended when
making connections to existing. This type of coupling are
applied without the use of heat and reduces the downtime. It
reduces the risk of fire in confined space and eliminates
carbon build-up on the interior of the pipe.
12.
RESEARCH AND CLINICAL LABORATORY GAS AND VACUUM SYSTEMS
Design laboratory compressed air, laboratory vacuum, natural gas and
miscellaneous laboratory cylinder gas systems in accordance with current
editions of NFPA 54 and 99, VA Master Specification 15488 and the
following:
12.1
Central Supply Systems:
A.
Provide minimum 690 kPa (100 psi) laboratory air at the
compressor discharge. Run 690 kPa (100 psi) air to a storage
room (or other non-working or unfinished space) in the
laboratory area being served. Valve and cap the 690 kPa
(100 psi) air line for future connection. Tee off the 690 kPa
(100 psi) line and locate a pressure regulating valve to
reduce the air pressure to 345 kPa (50 psi). Run 345 kPa (50
psi) air to all outlets in laboratory hoods and benches.
B.
If laboratory equipment being purchased by the medical center
is known, and items have requirements for higher air
pressures, provide additional tee, regulator, and piping to
that equipment at the required pressure.
C.
Natural gas, and manifolded laboratory gas system pressures
shall be determined on a project basis.
D.
Design laboratory vacuum systems to deliver 50 Pa (15 inches
Hg) at the point of use.
E.
Place a source shut-off valve for each laboratory gas and
vacuum system at the immediate outlet (or inlet, in the case
of vacuum) of the source of supply, so that the entire supply
source, including all accessory equipment, can be isolated
from the entire pipeline system.
F.
In facilities where manifolded laboratory gases occur, ensure
that adequately sized and properly constructed storage space
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