Information and Toxicology of Ammonia


Colorless gas in lower concentrations. In higher concentrations it can form a white cloud. An extremely pungent odor is detectable from 5 ppm and becomes irritating at 25 ppm. Liquid ammonia is transported under pressure.

Exposure Limits

TLV: 25 ppm REL: 25 ppm STEL: 35 ppm PEL: 50 ppm IDLH: 300 ppm

TWA (time weighted average): 8 hours

LC50 (Lethal Concentration 50): <5000 ppm for 30 min.

Physical Characteristics

Boiling Point: -28 °F.

Relative Gas Density: Vapor - 0.6 (air = 1, lighter than air)

Aerosol ->1.0

Specific Gravity: 0.62 (water = 1, lighter than water)

Solubility: - Very soluble in water

pH: 11 +


Ammonia is stable. It reacts with oxidizing agents and strong acids. Contact with chlorine, bromine, iodine and hypochlorites can be explosive. Ammonia and most acids will react with a great amount of heat given off during the neutralization. Ammonia will ignite in contact with nitric acid vapors. Ammonia will corrode copper, brass, bronze and galvanized steel.

Fire and Explosion Data

LEL: 15% UEL: 28%

It is a flammable gas at concentrations between these limits. This is particularly important in an enclosed area. Presence of oil will increase the fire hazard (LEL as low as 8%). Use flooding quantities of water until well after fire is out. Keep fire-exposed containers cool. Pressurized containers can rupture when overexposed to heat.

DOT Classification: Non-flammable gas.

Ammonia goes through hazardous decomposition at temperatures above 850 °F. Hydrogen and nitrogen are given off possibly resulting in an explosion may result.

Health Hazards

Major Routes of Entry are eyes, inhalation, and skin. Ammonia is corrosive to all body tissues. In liquid form, ammonia causes severe burns and frostbite on contact.

Eyes: Exposure to low concentrations of ammonia gas may cause irritation. In high concentrations, it could cause damage to the eyes, which then could cause blindness. Recommendation: Contact lenses should not be worn with gas or liquid present.

First Aid: Flush with water immediately for at least 15 minutes, particularly under the eyelid. See physician.

Inhalation: Exposure to gas above the TLV may cause irritation to nose, throat and lungs. Higher concentrations can cause uncontrolled coughing, lung congestion, vomiting and pulmonary edema.

First Aid: Get fresh air. See physician.

Skin: Exposure to gas can cause skin irritations, especially if the skin is moist. Liquid contact creates extreme burns and frostbite.

First Aid: Flush with water for at least 15 minutes. See physician.

Protection Information

Anytime the ammonia refrigeration system is opened to the atmosphere or whenever there is the possibility of exposure, utilize proper line break procedures. Always assume something will happen. Put on the PPE, open up the system and if there is no ammonia present, remove the PPE.

The minimum PPE is a full face piece air purifying respirator, and a pair of ammonia rate gloves.

For exposures between TLV and IDLH, use a full-face piece cartridge/canister air-purifying respirator. NEVER use a face shield or goggles for ammonia. They are not suitable. They will get you hurt. ONLY use a full face piece air purifying respirator.

Above the IDLH, use a positive pressure, supplied air respirator, and a totally encapsulating, positive pressure chemical suit.