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HVACR316 - Piping

HVACR316 - Piping. Fundamentals of Refrigeration Soldering and Brazing. Soldering and Brazing Basics. When and why: When an A/C or refrigeration system is installed, it must be properly sealed. Although flared fittings are widely used, most components are joined by soldering and brazing.

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HVACR316 - Piping

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  1. HVACR316 - Piping Fundamentals of Refrigeration Soldering and Brazing

  2. Soldering and Brazing Basics • When and why: • When an A/C or refrigeration system is installed, it must be properly sealed. • Although flared fittings are widely used, most components are joined by soldering and brazing.

  3. Soldering and Brazing Basics • Difference between soldering and brazing • Soldering is accomplished with temps under 800°F. • Brazing is accomplished with temps over 800°F; usually 1,000°F to 1,500°F.

  4. Soldering and Brazing Basics • Soldering • Soldering is an adhesion process. • Solder flows into tubing pores. • Joining takes place when solder hardens. • Solder has low tensile strength. • It is not recommended for A/C or refrigeration systems, due to the high temps and high pressures.

  5. Soldering and Brazing Basics • Newer solder gives the tensile strength of braze and lowers melting point of solder. • Known as silver bearing solder • StayBright 6 and StayBright 8 • Both contain silver

  6. Soldering and Brazing Basics • When soldering, flux must be used • Most common is Solderine • Proper cleaning, fluxing, assembly support, and heating is necessary. 1) Clean all surfaces to be soldered 2) Use clean flux on all ends 3) Do not overheat 4) Have parts properly supported

  7. Soldering and Brazing Basics • The solder has a lower melting point than the copper being joined. • Solder should be distributed evenly around and in the joint. • Heat the joint evenly, both tube and fitting • As flux clears, apply heat directly to the joint.

  8. Soldering and Brazing Basics • Capillary action will take place, leaving a proper fillet or cap. • No globs or drips should be present. • Joint should be cleaned with a cloth.

  9. Soldering and Brazing Basics • Brazing • Brazing is a common practice in HVAC/R. • On large applications, oxy-acetylene is used. • Most day-to-day operations can be done with a plumber’s torch and acetylene. • Brazing is a welding practice.

  10. Soldering and Brazing Basics • Unlike soldering, brazing can be done to join two dissimilar metals. • Many different alloys or filler metals are available for HVAC/R work. • Most common: • 5% Silver • 15% Silver • 45% Silver

  11. Soldering and Brazing Basics • The greater the silver content, the greater the tensile strength: • 5% and 15% are sold by the pound • 45% is sold by the troy ounce • Flux • When brazing, silver flux must be used. • It cleans the metal and acts as a temperature indicator. • It assists in alloy flow and prevents oxidation.

  12. Soldering and Brazing Basics • Heat both Fitting and Tube. • Flux will turn powdery white and suddenly clear. • Clearing is an indication of about 1,100°F. • Apply alloy (braze); very little is needed • Capillary action will take place. • Alloy (braze) will flow at around 1,100°F to 1,250°F. • As flow starts, remove alloy and flame.

  13. Soldering and Brazing Basics • Cool the joint and clean to remove excess flux (excess flux could hide a pinhole leak).

  14. Soldering and Brazing Basics • Heating of the joint for soldering and brazing • If heating at the compressor • Do the joint closest to the compressor first, using a wet rag (or heat absorbing paste) as a heat shield. • Whether soldering or brazing, avoid overheating; glowing red produces scale.

  15. Soldering and Brazing Basics • Equipment • Oxy-acetylene • Extremely hot; may also be used for cutting • Not for residential or rooftop use • Intended for work shop and construction site use

  16. Soldering and Brazing Basics • Tanks: • “B” tank or “MC” tank sizes • Can be an unguided missile if not properly secured, the tank is under 250 psi • Impact as little as 15 psi can cause valve to rupture • Tank is cork lined • The valve is opened only ½ turn with a tank wrench

  17. Soldering and Brazing Basics • Tank Safety • Acetylene is heavier than air. It can puddle on floor, removing oxygen from the room, resulting in an explosion hazard. • Leak test each time the tank is first opened or changed, using only a bubble solution. • Always secure the tank. • Store and use in upright position only.

  18. Soldering and Brazing Basics • Regulators • 2 types • Adjustable and non-adjustable • Adjustable • Flame is adjusted with the regulator, not the torch handle • Non-Adjustable • Flame must be adjusted with the torch handle, handle is not made for fine tuning

  19. Soldering and Brazing Basics • Hose, Handle, and Tip • All should be leak-checked when checking the regulator. • Tips are interchangeable. • New tips are called swirl tips, the give off a hotter flame for brazing larger tubing. • Blue tip of flame is the hottest.

  20. Soldering and Brazing Basics • General Safety • Wear safety glasses at all times. • Never use pliers on any part of torch setup. • After use: • Shut tank off at valve • Bleed hose • Coil hose • Light torch only using striker. • Adjust flame for different sized tubing.

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