Ammonia questions
The most commonly used refrigerant in flooded type industrial refrigeration system anhydrous ammonia (chemical symbol Nh3, the number of R717 refrigerant). Anhydrous ammonia has a high latent heat as a result of low refrigerant mass flow around the circuit and, therefore, reduced energy consumption.
The density of the liquid ammonia is less than the compressor lubricating oil. Thus, removal of oil is just draining of the lower points of the system (for security, low-pressure side of the system, and in containers for collection of oil). Ammonia vapour is about two-thirds from the air density and, thus, the air is easily cleaned from the highest point capacitor when the refrigerating plant is stopped or automatic cleaning equipment. Since both of these pollutants can significantly influence the energy efficiency of ammonia and systems, their removal is very important.
Ammonia has good heat transfer properties in the liquid and vapor phases.
Ammonia is toxic at high concentrations. COSHH extremely monitor the effects of ammonia on 25 ppm, which indicates that the smell is quite obvious. Vapour concentrations up to 250 ppm can be tolerated by most people, calling only irritation and discomfort no cumulative effect. 3500 ppm ammonia quickly fatal (30 minutes). 16 - 27% (vol.) ammonia-air mixture can, with difficulty, to ignite. Ammonia attacks also copper, zinc, lead, tin, cadmium and their alloys.
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Refrigerants