Copper for refrigerant piping in HVAC segment

February 28, 2014 5:53 am

Copper tube is the preferred choice of modern contractors for plumbing, heating and cooling installations in all kinds of residential and commercial buildings, explains Shankar Sapaliga, Sr. Consultant HVAC, ICPCI
Copper tube for various applications such as plumbing, heating, cooling and refrigeration and air-conditioning industries is available in drawn and annealed tempers in a range of diameters and wall thicknesses. In United States, copper tube is manufactured to meet the requirements of specifications established by ASTM International.
Types of copper tubesType K, L, M, DWV and medical gas tubes are designated by ASTM Standard sizes, with the actual outside diameter always 1/8-inch larger than the standard size. Each type represents a series of sizes with different wall thicknesses. Type K has thicker wall thickness than Type L and Type L has thicker wall thickness than Type M for any given diameter. Copper tube for air conditioning and refrigeration (ACR) field service is designated by actual outside diameter.
The tube type, the name or the trademark of the manufacturer and the country of origin are printed on it in a colour to distinguish its tube type. Soft ACR tube may not carry anyincised or colour markings.
Copper tubes are further classified ashard drawn temper tube and soft temper. Tube in the hard temper condition is usually joined by brazing or soldering. The soft tube can be joined by same technique and by use of flare type and compression fittings. Further, it is possible to expand the end of one tube so that it can be joined to another by soldering or brazing without a capillary fitting.
Advantages of copper tubeCopper tube is the preferred choice of modern contractors for plumbing, heating and cooling installations in all kinds of residential and commercial buildings in many parts of the world because:• Copper tubes are easy to handle, joining and forming saves installation time and cost and reliable with its long term  performance. It is light weight and due to formability it is frequently possible to eliminate elbows and joints. • Copper is safe as it will not burn or support combustion or decompose to toxic gases. It will not carry fire through walls, floors  and ceilings.• Copper is long lasting and has excellent resistance to corrosion and scaling, high mechanical strength, high temperature  resistance and life time resistance to UV degradation.• Copper is 100 per cent recyclable and can be recycled over and over without degradation in content or properties.
Refrigerant piping for HVAC systemApplication considerationsFollowing are the additional factors to be considered while designing piping for the refrigerant flow:• The system must be designed for minimum pressure drop since pressure loss decreases the thermal capacity and increases the power requirement in a refrigeration system.• The fluid being piped changes in state as it circulates.• Since lubricating oil is miscible with refrigerant s, some provision must be made to : • Minimise the accumulation of liquid refrigerant in the compressor crank case • Return oil to the compressor at the same rate at which it leaves.

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