SERVICE - TM-9-4120-425-14-P0222

TM 9-4120-425-14&P

REFRIGERATION SYSTEM SERVICING (BRAZING/DEBRAZING) - Continued

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SERVICE - Continued

Filler Alloy Information

Grade IV or Vl brazing alloy and Type B flux, as specified in MIL-B-7883, must be used for all copper to brass joints.

Grade III brazing alloy may be substituted for Grade IV or VI for copper to copper joints; flux is not required for copper

to copper joints.

Debrazing

Debraze joints for removal of refrigeration system components as follows:

WARNING

All refrigerant-22 must be discharged from the system and the entire system must be

purged with dry nitrogen before beginning any debrazing operation.

Determine which joints are to be debrazed. Due to the limited work space inside the air conditioner, it may be more

convenient to remove a part of the interconnecting tubing with the component rather than debrazing the joints on the

component itself.

Before debrazing a joint on a valve, disassemble the valve to the extent possible, then wrap all but the joint with a

wet rag to act as a heat sink.

WARNING

The elastomeric foam used as insulation in the air conditioner may be damaged and

break down to form toxic gasses if exposed to the flame of a torch at brazing

temperature.

Protect insulation, wiring harnesses, cabinet, and other surrounding components with appropriate

shields.

Be sure the work area is well ventilated. Be sure the refrigeration system is fully discharged and purged, and that dry

nitrogen is flowing through the refrigeration system at a rate of less than 1-2 cfm (0.028- 0.057 m3/minute.)

Apply sufficient heat uniformly around the joint to quickly melt the filler alloy. If heat is applied slowly, or only on

one side, the entire component or length of tubing will be heated and filler alloy in adjacent joints may also be

melted. Remove heat as soon as the joint separates.

Cleaning Debrazed Joints

All filler alloy must be cleaned from debrazed joints before reassembly. Heat each piece of the joint until the filler alloy

is melted and then wipe it away with a dry cloth. Be sure no filler alloy or other debris are left inside any tubing, fitting

or component.

Reassembly

If tubing sections or fittings were removed with a component, debraze them from the component, clean the joints, and

braze them to the new component before reinstallation.

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