Refrigeration grade

Material content Commercial or ferti1i2er grade Refrigeration grade Metallurgical grade... 

Refrigeration-grade silica gel, 14- to 20-mesh, obtained from (he Davison Chemical Corporation, Baltimore, Maryland, was used. 

A 1-1. three-necked flask is equipped with a mercury-sealed stirrer, an inlet tube, and a reflux condenser which is connected through a soda-lime tube to a gas-absorption trap.1 The apparatus is dried in an oven and assembled rapidly to exclude moisture it is advisable to set up the apparatus in a hood to vent ammonia which may escape by accident. The flask is cooled in a Dry Ice-trichloroethylene bath, and 200 ml. of anhydrous (refrigeration grade) ammonia is introduced through the inlet tube from an ammonia cylinder which is either inverted or equipped with a siphon tube. Just before the apparatus is assembled, 8.1 g. (0.35 gram atom) of sodium is cut, weighed, and kept under kerosene in a small beaker. The Dry Ice bath is removed, the inlet tube is replaced by a rubber stopper, and a crystal of hydrated ferric nitrate (about 0.2 g.) is added. A small (about 5-mm.) cube of the sodium is cut, blotted rapidly with filter paper, and added quickly to the liquid ammonia. The solution is stirred until the blue color disappears, after which the remainder of the sodium is added in narrow, thin strips about as rapidly as... 

The ammonia was commercial refrigeration grade which was distilled into and stored in small stainless steel cylinders containing sodium metal, from which it was distilled as necessary. The ammonia used in... 

Commercial grade is produced by ammonia synthesis while refrigeration grade is normally made from industrial raw ammonia by distillation. For ammonia shipped or pipelined in the United States, water content must be at least 0.2 weight% to inhibit stress corrosion cracking of the carbon steel.57... 

Artie [Du Pont], TM for refrigeration grade of methyl chloride. 

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