Soldering
This chemical cleans and prepares metal surfaces so solder will bond properly.
What is flux?
This color of flame indicates too much oxygen and can damage copper tubing.
What is an oxidizing flame?
This torch setup produces the hottest flame commonly used in HVACR brazing.
What is oxy-acetylene?
This type of clothing material is preferred over synthetics because it will not melt to the skin.
What is cotton (or natural fiber clothing)?
This must always be removed from refrigeration lines before applying a torch to prevent an explosion.
What is a refrigerant?
This action allows molten solder to be drawn into a joint by surface tension.
What is capillary action?
If nitrogen is not used during brazing, this black flaky contamination forms inside the tubing.
What is copper oxide scale?
This dangerous condition can occur if a torch tip overheats or pressures are set incorrectly, causing the flame to travel backward.
What is a flashback?
This respiratory protection may be required when working in poorly ventilated spaces to avoid inhaling flux fumes.
What is a respirator?
This device must be kept nearby whenever open flame work is being performed.
What is a fire extinguisher?
This improper heating mistake burns flux and prevents solder from bonding correctly.
What is overheating the joint?
This condition can occur if the joint is overheated, causing the copper to weaken and possibly crack later.
What is annealing?
This is the correct shutdown order for an oxy-acetylene torch at the handle.
What is turn off the acetylene first, then the oxygen?
These lenses are recommended when using oxy-acetylene to reduce glare and protect eyes from intense flame brightness.
What are shade 4 or 5 tinted lenses?
Acetylene should never be set above this pressure because it becomes unstable.
What is 15 psi?
This minimum clearance between pipe and fitting is required for proper capillary action in a soldered joint.
What is approximately 0.002–0.005 inches?
A system repeatedly plugs TXVs after installation. The likely brazing mistake was failing to do this.
What is nitrogen purging during brazing?
A student is trying to braze a 7/8” suction line with propane and cannot get the joint hot enough. The problem is this.
What is insufficient flame temperature / wrong fuel choice?
This specific glove characteristic is important because thin mechanic gloves may melt under high heat.
What is leather or flame-resistant material?
This toxic gas can form if refrigerant is exposed to an open flame.
What is phosgene gas?
This is the most likely cause if a joint leaks even though it “looked good” after cooling.
What is movement during cooling or insufficient capillary fill?
When brazing near a service valve, this internal component must be protected or removed to prevent failure.
What are the valve core or internal seals (Schrader/core components)?
The copper turns black inside during brazing, even though nitrogen is flowing. This flame condition is likely being used.
What is an oxidizing flame?
This foot protection prevents injury if a hot fitting or torch is dropped during brazing.
What are steel-toe boots?
A tech brazes near a TXV without protecting it, and it fails shortly after startup. The safety step missed was this.
What is using a wet rag or heat-blocking compound to protect components?