While brazing can be taught in a classroom environment, it takes practice in field conditions to become proficient. In the field, brazing can be a challenge because there are flammable items nearby, difficult access, and awkward positions to contend with. It is used to connect refrigerant tubing to equipment when installing or repairing an HVAC system. It is one of the best methods of making leak-proof connections. Brazed joints are strong and can withstand high temperature and pressure conditions.
Oxyacetylene equipment is most often used when brazing. Oxygen and acetylene are combined to produce a flame that reaches a maximum temperature of 6000F. This allows for fast heating and a minimal amount of heat transfer down the tubing, allowing a technician to braze in parts without damaging them through heat transfer.
The correct use of oxyacetylene brazing equipment requires the proper adjustment and metering of oxygen and acetylene. Here are some basic procedures:
Remember -
Air must be removed from the tubing that is being brazed by purging the tubing with nitrogen or carbon dioxide. NEVER use refrigerant, oxygen, or compressed air to purge the tubing.
The proper Braz temperature is indicated by the color of the secondary flame. The secondary flame will turn green.
When heating a copper to steel joint, heat the copper first. It takes more heat because it carries the heat away faster than steel.
When brazing a capillary tube, take care not to let brazing material run into the end of the tube. If you leave a small end of the capillary tube uncleaned it will help prevent this from happening.
Larger torch tips allow a softer flame and a larger quantity of heat. It also helps prevent burning through the tubing with a higher pressure flame.
These techniques can be learned and practiced but proper brazing is a skill that takes practice in the field. Our online HVAC Classes will introduce you to the proper brazing techniques.
by Ron Walker
Oxyacetylene equipment is most often used when brazing. Oxygen and acetylene are combined to produce a flame that reaches a maximum temperature of 6000F. This allows for fast heating and a minimal amount of heat transfer down the tubing, allowing a technician to braze in parts without damaging them through heat transfer.
The correct use of oxyacetylene brazing equipment requires the proper adjustment and metering of oxygen and acetylene. Here are some basic procedures:
- Degrease and clean tubing and parts thoroughly.
- Fit and support the joints.
- Heat evenly moving the flame in a figure 8 motion.
- Wait for the flame to turn green in color.
- Apply the brazing rod to the joint. Do not melt the brazing rod with the torch.
- Cool the joint.
Remember -
Air must be removed from the tubing that is being brazed by purging the tubing with nitrogen or carbon dioxide. NEVER use refrigerant, oxygen, or compressed air to purge the tubing.
The proper Braz temperature is indicated by the color of the secondary flame. The secondary flame will turn green.
When heating a copper to steel joint, heat the copper first. It takes more heat because it carries the heat away faster than steel.
When brazing a capillary tube, take care not to let brazing material run into the end of the tube. If you leave a small end of the capillary tube uncleaned it will help prevent this from happening.
Larger torch tips allow a softer flame and a larger quantity of heat. It also helps prevent burning through the tubing with a higher pressure flame.
These techniques can be learned and practiced but proper brazing is a skill that takes practice in the field. Our online HVAC Classes will introduce you to the proper brazing techniques.
by Ron Walker