Refrigerants halogens

SB-18 Use of Refrigerant (Halogenated Hydrocarbons) Recovery Cylinders. Recommends safe practices for those who supply, use, store, or transport recovery cylinders (2 pages). 

Chemical compounds manufactured at petrochemical plants include methanol, formaldehyde, and halogenated hydrocarbons. Formaldehyde is used in the manufacture of plastic resins, including phenolic, urea, and melamine resins. Halogenated hydrocarbons are used in the manufacture of silicone, solvents, refrigerants, and degreasing agents. 

In refrigerating systems, halogen derivatives of methane and ethane marketed under the trade names of Arctons and Freons are without action on pure aluminium and its copper-free alloys in dry conditions, but in wet conditions monochlorodi-, dichloromono-and trichloromonofluoromethanes can hydrolyse to produce slight attack on the aluminium. 

MILLS,. 1. E. D., Development of international control measnres on the prodnction and nse of fnlly halogenated chloroflnorocarbons. Proceedings of the Institute of Refrigeration, Eondon, 1987... 

Reclaimed halogenated hydrocarbons can be used as refrigerants, solvents, cleaners, fumigants, and fire retardants. 

Occasionally leaks can also be located or detected by means of chemical reactions which result in a discoloration or by penetration of a dye solution into fine openings. The discoloration of a flame due to halogen gas escaping through leaks was used earlier to locate leaks in solder joints for refrigeration units. 

Gaseous chemical compounds whose molecules contain chlorine and/or fluorine - such as refrigerants R12, R22 and R134a - will influence the emissions of alkali ions from a surface impregnated with a mixture of KOH and lron(lll)hydroxide and maintained at 800 °C to 900 °C by an external Pt heater. The released ions flow to a cathode where the ion current is measured and then amplified (halogen diode principle). This effect is so great that partial pressures for halogens can be measured down to 10 mbar. 

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