drive shaft. Provide positioners where indicated and where necessary to
prevent overlap of heating and cooling where one controller operates more
than one pneumatic device and to maintain the proper dead band between
heating and cooling.
3.1.7
Access Doors
Provide access doors in ductwork to service airflow monitoring devices,
devices with averaging elements, and low-temperature protection thermostats
(freezestats).
3.1.8
Tubing
a.
Provide control system so that pneumatic lines are not exposed to
air temperatures below minus 4 degrees C 25 degrees F. Install
tubes and tube bundles exposed to view neatly in lines parallel to
lines of the building. Route tubing between panels and actuators
in mechanical and electrical spaces so that lines are easily
traceable. Tubes shall be permanently tagged on both ends with an
identifier indicated on shop drawings. Install concealed tubing
in finished areas, and install exposed tubing in unfinished areas
such as mechanical equipment rooms.
b.
Pneumatic lines in mechanical and electrical spaces shall be
plastic tubing or copper tubing. Install horizontal and vertical
runs of plastic tubes or soft copper tubing in raceways dedicated
to tubing. Dedicated raceways shall be supported every 2 meters 6
feet of horizontal run and every 2.44 meter 8 feet for vertical
runs. Tubing not installed in raceways shall be hard-drawn copper
tubing with sweat fittings and valves, supported every 2 meter 6
feet of horizontal run and every 2.44 meters 8 feet for vertical
runs.
c.
Tubing for connecting sensing elements and transmitters to liquid
and steam lines shall be [copper] [Series 300 stainless steel]
with [brass compression] [stainless steel compression] fittings.
d.
Tubing for final connection of sensing elements and transmitters
to ductwork shall be plastic with a maximum length of 305 mm 12
inches.
e.
Tubing external to mechanical and electrical spaces, where run in
plenum ceilings, shall be soft copper with sweat fittings,
supported every 2.44 meters 8 feet. Tubing not in plenum spaces
shall be soft copper with sweat fittings supported every 2.44
meters 8 feet or shall be plastic tubing in raceways dedicated to
tubing.
f.
Provide tubing in concrete in rigid conduit. Install tubing in
walls containing insulation, fill, or other packing materials in
raceways dedicated to tubing.
g.
Final connections to actuators shall be plastic tubing, a maximum
of 305 mm 12 inches long and unsupported at the actuator.
h.
Provide a manual valve at each HVAC control panel to allow shutoff
of main air. Pneumatic connections to HVAC control panels shall
be made using bulkhead fittings except where bundled tubing is
being used.
SECTION 15901N
Page 45
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