Table of Contents
Advertisement
•
Use Type K per ASTM B 88 or ASTM B 819 or Type ACR per ASTM B280 copper tubing or for all
tubes 1 1/8" and smaller.
•
Tubes 1 3/8" and larger shall use Type K per ASTM B 88 or ASTM B 819.
•
Cap sections of tube and components that are not actively being installed to prevent infiltration of
moisture and contaminants.
•
Use only braze alloy to join tube.
-
•
Flow nitrogen into tubing to prevent the formation of copper oxides.
-
-
•
See section 5.1.1 for special procedures related to compressor replacement
•
Replace liquid line filter dryer as last step in system repair. Note that the dryer will readily absorb
moisture from the ambient air and must be open only for as long as required for installation.
•
After completion of all repairs, pressure test system using nitrogen pressure decay test or nitrogen
with tracer gas and appropriate leak detector.
Evacuation
•
Carefully inspect pump and related equipment before connecting to system. Ensuring gaskets are in
good condition and pump is capable of low vacuum levels can save time. Connect pump(s) to as
many locations as possible ensuring all locations are well sealed. If a field charge will be required,
The selection of filler metals is highly dependent on the tube fit, clearance, and operator
preference for flow. When flux is to be used, care should be taken to ensure that the flux is
not introduced to the inside of the tube. It is recommended that phosphorous bearing alloys
be considered for copper to copper connections due to their self-fluxing on copper to copper
joints. Refer to alloy manufacturer's guidelines for details on compatibility.
Copper oxides form rapidly when copper is heated to temperatures required by the brazing
process and exposed to oxygen in the air. Copper oxides flake easily on the inside of the
tubing and dislodge easily when the system is filled with refrigerant and oil. The particulate
can move throughout the system and cause contamination on valves and other critical
components. System filters may become fouled.
Flowing nitrogen into the system and ensuring that the inside of the tube is significantly
free from oxygen while brazing ensures that oxides do not form. As the last joints of a system
are made, additional thought must be made on the location where the nitrogen can escape.
Schrader valves are placed throughout the system. These valves can be opened to allow for
nitrogen to flow without generating pressure behind the braze joint that is being created.
Desert Aire - QS/QV Manual
79
Hide quick links:
Advertisement
Table of Contents
