R-Pro › Field cases › Air conditioning
Flare vs Brazing — Field Selection Criteria
Likely causes
Capacity / pipe size / pressure / maintenance — 4 criteria
Check: **Flare**: ① Residential ≤15HP. ② Pipe sizes 1/4, 3/8, 1/2, 5/8. ③ R-410A op pressure (LP 100-120, HP 350-400 psi). ④ Allows disassembly/move/reinstall. **Brazing**: ① Industrial ≥20HP, VRF, refrigeration. ② Pipe ≥7/8. ③ Pressure can exceed 600 psi. ④ Permanent/embedded/vibration. R-32/R-454B (A2L flammable) restricted for indoor brazing in Korea (ventilation/fire code).
What to do: Flare: torque wrench (1/4=17-24, 3/8=33-41, 1/2=49-62 N·m). Hand-tight then 5 min with torque wrench. Brazing: nitrogen purge at 0.5 MPa concurrently → phos-copper 7%/15% silver rod (Sil-Phos), 700-800°C. Anti-oxidation essential (without N₂ purge, internal oxide → EEV/drier blocked). Double vacuum time after brazing (remove residual oxide).
Korea OSHA — brazing requires 5m clearance from flammables + fire extinguisher. After draining R-32 system, purge nitrogen 5 min before brazing (fire risk). Embedded pipe (new apartment) = brazing only (can't disassemble). Residential <1HP = 90%+ flare. Tech without torque wrench = hand-tight only → 80% of leak causes.
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