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Tightening the Flare Nuts
Tightening Torque for Flare Nuts.
Pipe Size (in. O.D.)
Outside Diameter (mm)
1/4
3/8
1/2
5/8
3/4
1. When connecting the flare nuts, coat the flare (outside only) with polyvinyl ether (PVE) refrigeration oil only.
Do not use polyolyester (POE) or any other type of mineral oil as a thread lubricant. These lubricants are not compatible with the PVE oil
used in this system and create oil sludge leading to equipment damage and system malfunction.
Do not add any contaminants inside the refrigerant piping.
2. Initially hand tighten the flare nuts using three (3) or four (4) turns.
3. To finish tightening the flare nuts, use both a torque wrench and a backup wrench.
4. After all the piping has been connected and the caps have been tightened, check for refrigerant gas leaks.
Loosening the Flare Nuts
Always use two (2) wrenches to loosen the flare nuts.
Brazing Practices
WARNING
Do not braze in an enclosed location.
before and after brazing.
If the refrigerant combusts, it generates a toxic gas the will cause physical injury or death.
1. Joints are brazed in the field. Single Zone refrigeration system components
contain very small capillary tubes, small orifices, electronic expansion valves, oil
separators, and heat exchangers that can easily become blocked. Proper system
operation depends on the installer using best practices and utmost care while
assembling the piping system.
2. Store pipe stock in a dry place; keep stored pipe capped and clean.
3. Blow clean all pipe sections with dry nitrogen prior to assembly.
4. Always use a non-oxidizing material for brazing.
anti-oxidant agents. If the proper material is not used, oxidized film will accumulate
and clog or damage the compressors. Flux can harm the copper piping or refrigerant oil.
5. Use a tubing cutter,
do not use a saw to cut pipe. De-bur and clean all cuts before assembly.
6. Brazing joints:
• Use a dry nitrogen purge operating at a minimum pressure of three (3) psig and maintain a steady flow.
• Use a 15% silver phosphorous copper brazing alloy to avoid overheating and produce good flow.
• Protect isolation valves, electronic expansion valves, and other heat-sensitive control components from excessive heat with a wet rag or
heat barrier spray.
WARNING
•
Do not allow the refrigerant to leak during brazing; if the refrigerant combusts, it generates a toxic gas. There is risk of fire, explosion, and
physical injury or death.
•
Do not braze in an enclosed location, and always test for gas leaks before / after brazing. There is risk of fire, explosion, and physical
injury or death.
FLARING AND BRAZING PROCEDURES
Tightening Torque (ft-lbs.)
13.0 - 18.0
6.35
9.52
24.6 - 30.4
12.7
39.8 - 47.7
15.88
45.4 - 59.3
71.5 - 87.5
19.05
Do not allow the refrigerant to leak during brazing. Always test for gas leaks
Do not use flux, soft solder, or
©
Figure 28: Refrigerant Pipe Brazing.
Refrigerant
Piping
Pipe to
be brazed
Nitrogen
Taping
Pressure-reducing
Valve
Valve
37
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