Materials used in the construction of refrigeration, air-conditioning and heat pump systems are standard engineering materials, but there are a few special points of interest:
1. Compressor bodies are generally of gray cast iron, although some are fabricated from mild steel. Hermetic types have steel shells.
2. Compressor pistons are of cast iron or aluminium, the latter following automobile practice.
3. Piping for the smaller halocarbon installations is usually of copper, because of the cleanliness and the ease of fabrication and jointing.
4. Some stainless steel pipe is used, mainly because of its cleanliness, although it is more difficult to join.
5. Most other piping is mild steel. For working temperatures below -45°C, only low-carbon steels of high notch strength are used.
6. Aluminium tube is used to a limited extent, with the common halocarbons and also with ammonia.
7. Copper and its alloys are not used with ammonia.
8. Sheet steel for ductwork, general air-conditioning components, and outdoor equipment is galvanized.
Specific guidance on materials and their application may be had from various works of reference.
Posted in Refrigeration and Air Conditioning