ANHYDROUS AMMONIA (NH3)
NH3
- Anhydrous ammonia is a compound formed by the combination of two (2) gaseous elements, nitrogen and hydrogen.
- Ammonia is one (1) part nitrogen to three (3) parts hydrogen. (NH3)
- Ammonia by weight is fourteen (14) parts nitrogen to three (3) parts hydrogen that is approximately 82% nitrogen to 18% hydrogen.
NH3 Vapor
- Ammonia appears in nature as a natural substance that results from decomposition.
- Ammonia vapor is a colorless gas with a pungent odor.
- Ammonia exists as a vapor at atmospheric conditions.
- Ammonia vapor is lighter than air and tends to rise when released to atmosphere. anhydrous ammonia nh3
NH3 Liquid
- Liquid ammonia released to atmosphere forms a white smoke by freezing the moisture in the air.
- Liquid ammonia has a very high coefficient of expansion with temperature.
- One (1) gallon of liquid ammonia weighs approximately 5 lbs; however, the weight varies with temperature.
- When liquid ammonia reaches a temperature between its melting and critical points, it exerts a vapor pressure that increases with temperature.
- A closed container of liquid ammonia is in equilibrium with ammonia vapor and the container pressure bears a definite relationship to the temperature.
Physical Data
- Boiling point is at -28° F.
- Freezing point is at -107.9° F; a white crystalline mass forms.
- Critical temperature is at 270.3° F; ammonia exists as a vapor, regardless of pressure above this temperature.
- Density of ammonia liquid is 42.57 pounds per cubic feet @ -28° F; ammonia liquid is lighter than water.
- Density of ammonia vapor is .5970 pounds per cubic feet compared to air at atmospheric pressure and @ 32° F.
- Volume: One (1) pound of ammonia vapor occupies a volume of 22.78 cubic feet at 32° F and atmospheric pressure. One (1) pound of ammonia vapor occupies a volume of 22.5 cubic feet and yields 45 cubic feet of dissociated gas at a ratio of 25% nitrogen and 75% hydrogen @ 70° F and atmospheric pressure.
- Ammonia begins dissociating into nitrogen and hydrogen at approximately 850° F. anhydrous ammonia nh3
Storage & Handling
- Ammonia is stored and transported as a liquid under pressure.
- The pressure on the tank is the liquid pressure and remains the same whether the tank is 10% or 80% full.
- The maximum filling level of an anhydrous ammonia tank is 85%.
- Ammonia has a great affinity for water, so special care must be taken to keep the ammonia dry.
Flammability
- Anhydrous ammonia is classified by the DOT as a non-flammable gas.
- Ammonia vapor is flammable over a narrow range of 16% to 25% by volume in air and a strong ignition source must be present.