Compression fittings are mechanical connectors that seal a pipe by compressing a ferrule (metal or plastic ring) against the tubing when a nut is tightened over a tapered seat. This method creates a watertight joint without soldering, welding, or special tools beyond a wrench. Compression fittings work on copper, PEX, and some plastic pipes up to 2 inches diameter.
Technical Design
The fitting consists of a body with a tapered internal seat, a ferrule that deforms under pressure, and a compression nut. As the nut tightens, the ferrule compresses between the nut and pipe, forming a seal. Fittings are rated for pressures up to 150 PSI and temperatures matching the pipe material limits. Proper assembly requires finger-tight engagement plus one to two wrench turns.
HVAC Installation Advantages
Compression fittings require no special tools, solder, or glue, making them ideal for emergency repairs and field installations. They are reusable and can be disassembled without damaging the pipe, facilitating system modifications. Installation takes seconds and requires minimal training.
Limitations and Applications
Compression fittings cost more per connection than sweat fittings or adhesive connections. They are prone to leaking if over-tightened or under-tightened, requiring careful workmanship. They are suitable for low-vibration water systems but less ideal for pressurized refrigerant lines where soldered connections provide superior reliability.