2.11.22
Air Vents
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NOTE: Air vent locations will be indicated on
drawings; distinguish between manual and automatic
air vents.
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2.11.22.1
Manual Air Vents
Manual air vents shall be brass or bronze valves or cocks suitable for the
pressure rating of the piping system and furnished with threaded plugs or
caps.
2.11.22.2
Automatic Air Vents
Automatic air vents shall be 20 mm 3/4 inch quick-venting float and vacuum
air valves. Each air vent valve shall have a large port permitting the
expulsion of the air without developing excessive back pressure, a
noncollapsible metal float which will close the valve and prevent the loss
of water from the system, an air seal that will effectively close and
prevent the re-entry of air into the system when subatmospheric pressures
prevail therein, and a thermostatic member that will close the port against
the passage of steam from the system. The name of the manufacturer shall
be clearly stamped on the outside of each valve. The air vent valve shall
be suitable for the pressure rating of the piping system.
2.11.23
Steam Traps
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NOTE: The design engineer, when designating steam
using equipment or special steam applications, will
indicate the type of steam trap required in
accordance with the following data:
a. Inverted Bucket Traps: This type of trap
continuously vents air and carbon dioxide at steam
temperature and is recommended for modulating loads.
The bucket floats on steam to close the outlet and
sinks into condensate to open the condensate outlet.
Any trapped air is discharged first into the
condensate return line and is followed by condensate
discharge. This type of trap has the longest life
on systems under modulated control. When large
amounts of air are anticipated, an external
thermostatic air vent should be installed on a line
bypassing the trap to bleed air from the steam line
and discharge it to the condensate return line.
This system will give optimum performance at low
steam pressures with maximum dependability. These
traps will handle condensate from fan coil units
where condensate must be lifted to return lines
located above the equipment. They operate best at
near full load conditions where loads do not vary
over a wide range. Before operation, traps must be
primed by filling them with water.
b.
Vertical Open-Top Bucket Trap:
Trap
SECTION 15569A
Page 53
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