Multilayer composite tube with flame-resistant layers

A refrigeration system comprising:

• a compressor;
• an evaporator coil;
• a composite refrigeration line set coupled between the compressor and the evaporator coil to form a fluid circuit between the compressor and the evaporator coil, the composite refrigeration line set comprising:
• a suction line;
• and
• a return line;
• characterized in that one or more of the suction line and the return line are a composite refrigeration line set tube comprising:
• an inner plastic tube;
• a first adhesive layer external to the inner plastic tube;
• an aluminum layer circumferentially surrounding the first adhesive layer and coupled to the inner plastic tube via the first adhesive layer;
• a second adhesive layer external to the aluminum layer;
• and
• an outer plastic layer circumferentially surrounding the aluminum layer and coupled to the aluminum layer via the second adhesive layer;
• wherein:
• the inner plastic tube is polyethylene of raised temperature;
• the outer plastic tube is polyethylene of raised temperature;
• and
• the outer plastic tube comprises a flame-resistant compound combined with the polyethylene of raised temperature;
• and
• wherein the composite refrigeration line set tube has a flame and smoke spread rating of no more than 25/50 when tested in isolation using Appendix A1.22 of the CAN/ULC-S102-10 Standard Test Method for Surface Burning Characteristics of Building Materials and Assemblies;
• and
• a refrigerant received within the fluid circuit.

A refrigeration system comprising:

• a compressor;
• an evaporator coil;
• a first pair of compression fittings coupled to the compressor;
• a second pair of compression fittings coupled to the evaporator coil;
• a composite refrigeration line set coupled between the compressor and the evaporator coil via one of the compression fittings to form a fluid circuit between the compressor and the evaporator coil, the composite refrigeration line comprising:
• a suction line;
• and
• a return line;
• and
• a refrigerant received within the fluid circuit;
• wherein each of the compression fittings comprises:
• a nipple comprising:
• a distal annular channel;
• a distal O-ring received in the distal annular channel;
• a plurality of medial barbs;
• a proximal annular channel;
• a proximal O-ring received in the proximal annular channel;
• and
• a first threaded region;
• a ferrule sized to fit over the nipple and compress a tubing end between the ferrule and the nipple;
• and
• a nut comprising:
• an axial bore sized to fit over the tubing end;
• a second threaded region complementary to the first threaded region of the nipple;
• and
• an internal geometry adapted and configured to apply compression to the ferrule when the nut is threaded proximally relative to the nipple;
• and
• wherein one or more of the suction line and the return line are a composite refrigeration line set tube comprising:
• an inner plastic tube;
• a first adhesive layer circumferentially surrounding the inner plastic tube;
• an aluminum layer circumferentially surrounding the first adhesive layer and coupled to the inner plastic tube via the first adhesive layer;
• a second adhesive layer circumferentially surrounding the aluminum layer;
• and
• an outer plastic layer circumferentially surrounding the aluminum layer coupled to the aluminum layer via the second adhesive layer;
• wherein:
• the inner plastic tube is polyethylene of raised temperature;
• the outer plastic tube is polyethylene of raised temperature;
• and
• the aluminum layer is butt-welded to itself.