shall be installed with stems positioned to facilitate operation and
maintenance. Isolating valves for pressure gauges and switches shall be
external to thermal insulation. Safety switches shall not be fitted with
isolation valves. Thermal wells for insertion thermometers and thermostats
shall extend beyond thermal insulation surface not less than 25 mm 1 inch.
Filter dryers having access ports may be considered a point of isolation.
Purge valves shall be provided at all points of systems where accumulated
noncondensible gases would prevent proper system operation. Valves shall
be furnished to match line size, unless otherwise indicated or approved.
Drain valves shall be provided in bottom of risers and low points of
ammonia piping.
3.1.12
Expansion Valves
Expansion valves shall be installed with the thermostatic expansion valve
bulb located on top of the suction line when the suction line is less than
50 mm 2 inches in diameter and at the 4 o'clock or 8 o'clock position on
lines larger than 50 mm 2 inches. The bulb shall be securely fastened with
two clamps. The bulb shall be insulated. The bulb shall be installed in a
horizontal portion of the suction line, if possible, with the pigtail on
the bottom. If the bulb is installed in a vertical line, the bulb tubing
shall be facing up.
3.1.13
Valve Identification
Each system valve, including those which are part of a factory assembly,
shall be tagged. Tags shall be in alphanumeric sequence, progressing in
direction of fluid flow. Tags shall be embossed, engraved, or stamped
plastic or nonferrous metal of various shapes, sized approximately 35 mm
1-3/8 inch diameter, or equivalent dimension, substantially attached to a
component or immediately adjacent thereto. Tags shall be attached with
nonferrous, heavy duty, bead or link chain, 14 gauge 14 gauge annealed
wire, nylon cable bands or as approved. Tag numbers shall be referenced in
Operation and Maintenance Manuals and system diagrams.
3.1.14
Strainers
Strainers shall be provided immediately ahead of solenoid valves and
expansion devices and where indicated. Strainers may be an integral part
of the expansion valve.
3.1.15
Filter Dryer
A liquid line filter dryer shall be provided on each refrigerant circuit
located so that all liquid refrigerant passes through a filter dryer.
Dryers shall be sized in accordance with the manufacturer's
recommendations. A dryer shall be installed so that it can be isolated
from the system, the isolated portion of the system evacuated, and the
filter dryer replaced. Dryers shall be installed in the horizontal
position except replaceable core filter dryers may be installed in the
vertical position with the access flange on the bottom.
3.1.16
Sight Glass
A moisture indicating sight glass shall be installed in refrigerant
circuits down stream of filter dryers and where indicated. Sight glass
shall be full line size.
SECTION 15652A
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