(a)

1. (1) Under moderate pressure, the gas liquefies, but upon release of the pressure, the liquid is readily converted into the gaseous phase.
2. (2) Advantage of this characteristic is taken by the industry, and for convenience the gas is shipped and stored under pressure as a liquid.

(c)

1. (1) At atmospheric temperatures and pressures, ammonia is a pungent and colorless gas and serves as its own warning agent.
2. (2) Since ammonia gas is lighter than air, adequate ventilation is the best means of preventing any accumulation.

(d)

1. (1) In the case of the pure product at atmospheric pressure and below negative twenty-eight degrees Fahrenheit (-28° F), anhydrous ammonia is a liquid.
2. (2) Anhydrous ammonia freezes to a white crystalline mass at negative one hundred seven and nine-tenths degrees Fahrenheit (-107.9° F).

(e)

1. (1) The common metals are not affected by dry ammonia.

2. (2) Moist ammonia will not corrode iron or steel, but will rapidly react with:

   1. (A) Copper;
   2. (B) Brass;
   3. (C) Zinc; and
   4. (D) Many alloys, especially those containing copper.
3. (3) It is required that only iron, steel, and certain nonferrous alloys which have proved to be satisfactory for ammonia service, be used for ammonia containers, fittings, and other equipment.

(f)

1. (1) The flammable limits of ammonia are presently classified from sixteen percent (16%) to twenty-five percent (25%) by volume in air.
2. (2) Experience has shown that ammonia is extremely hard to ignite in spite of these theoretical limits.