TIME-WEIGHTED AVERAGE (TLV-TWA): 25 ppm

SHORT-TERM EXPOSURE LIMIT (TLV-STEL) : 35 ppm

TLV Basis - CRITICAL EFFECT(S): Irritation

In many jurisdictions, exposure limits are similar to the ACGIH TLVs. Since the manner in which exposure limits are established, interpreted, and implemented can vary, obtain detailed information from the appropriate government agency in each jurisdiction.

Ammonia is generally not considered a serious fire or explosion hazard because ammonia-air mixtures are difficult to ignite and a relatively high concentration of the gas is required. However, a large and intense energy source may cause ignition and/or an explosion, particularly in a confined space. The flammable/explosion concentration range has been reported in various sources to be 15 to 28%. The explosive range is broadened to 15 to 79% by mixing with other combustible gases, (such as hydrogen and oxygen), by higher temperatures and by pressures greater than atmospheric. The presence of oil or combustible materials increases the fire hazard and the presence of iron lowers the ignition temperature from 850 to 651 deg C. Ammonia decomposes into flammable hydrogen gas at about 450-500 deg C. Toxic and irritating nitrogen dioxide can form during burning in air. Containers or cylinders may rupture violently due to overpressurization, if exposed to fire or excessive heat for a sufficient period of time, releasing flammable and toxic gases. Explosions of air-ammonia mixtures have occurred in confined spaces.

Ammonia is stable at normal temperatures. It decomposes into hydrogen and nitrogen at about 450-500 deg C. Decomposition will occur at lower temperatures in the presence of metals such as iron, nickel and zinc and, to a lesser extent, catalytic surfaces, such as porcelain and pumice. In the presence of catalysts, decomposition begins as low as 300 deg C and is complete at 500-600 deg C.

High temperatures, electric discharge, electric sparks, welding

Reported values vary widely; 0.6 to 53 ppm; geometric mean: 17 ppm (detection)

NOT RELIABLE - odour threshold is about the same magnitude as TLV.

This material is a CORROSIVE, COMPRESSED GAS. It may also be an EXPLOSION HAZARD, especially in confined spaces. Before handling, it is extremely important that engineering controls are operating and that protective equipment requirements and personal hygiene measures are being followed. People working with this chemical should be properly trained regarding its hazards and its safe use.

Immediately report leaks, spills or failures of the engineering controls. If ammonia is released, immediately put on a suitable respirator and leave the area until the severity of the release is determined. In case of leaks or spills, escape-type respiratory protective equipment should be available in the work area.

Never work alone with this chemical. Another person must be in view at all times and must be equipped and trained to rescue. Alternatively, precautions such as regular visual checks made by another person or a telephone call-in procedure should be taken to ensure the continued safety of lone workers or workers in remote locations.

Unprotected persons should avoid all contact with this chemical including contaminated equipment.

Consider using a closed handling systems for processes involving this material. If a closed handling system is not possible, use the smallest possible amounts in a well-ventilated area separate from the storage area. Prevent the release of gas into the workplace air. For large-scale operations, consider the installation of a leak detection system with an alarm.

Do not use with incompatible materials such as oxidizing agents (e.g., nitrogen oxide), halogens (e.g., chlorine, fluorine) and heavy metals (e.g., mercury, silver).

Inspect cylinders for damage or leaks before handling. Use the type of containers recommended by the manufacturer. Use corrosion-resistant transfer equipment. Regularly check storage tanks and transfer equipment for evidence of corrosion or leakage.

For large-scale handling operations use non-sparking ventilation systems, approved explosion-proof equipment and intrinsically safe electrical systems in areas of use. Keep aisles and exits free of obstruction. Avoid all ignition sources (e.g., sparks, open flames, hot surfaces). Do not use near welding operations. Keep away from heat. Post "NO SMOKING" signs. It is very important to keep areas where this material is used clear of other materials which can burn (e.g., cardboard, sawdust).

Never perform any welding, cutting, soldering, drilling or other hot work on an empty vessel, container or piping until all the ammonia has been cleared. Do not heat compressed gas cylinders. Do not handle cylinders with oily hands. Leave cylinder cap on cylinder until cylinder is secured and ready for use. Always secure cylinders to a wall, rack or other solid structure in an upright position.

Use the appropriate pressure regulator. Ensure equipment is compatible with cylinder pressure and contents. Follow supplier recommendations. Before connecting the cylinder for use, make sure that back feed from the system into the cylinder is prevented.

Do not open cylinder if damaged. Never use excessive force when opening. Open cylinder valve slowly to prevent rapid decompression and damage to valve seat. Keep cylinder valves clean and free from contaminants (particularly oil and water). Make sure valves on gas cylinders are fully opened when gas is used. Open and shut valves at least once a day, while cylinder is in use, to avoid valve 'freezing'.

Shut flow off at cylinder valve and not just at the regulator after use. Replace outlet caps or plugs and cylinder caps as soon as cylinder is disconnected from equipment.

Make sure cylinders are labelled clearly. Avoid damaging cylinders. Move cylinders by hand truck or cart designed for that purpose. Do not drop cylinders or permit them to bang against each other. Do not lift cylinders by the cap or with a lifting magnet.

Keep empty cylinders under slightly positive pressure. Do not use cylinders as rollers or for any other purpose than to contain the gas as supplied.

Follow handling precautions on Material Safety Data Sheet. Have suitable emergency equipment for fires, spills and leaks readily available. Practice good housekeeping. Maintain handling equipment. Comply with applicable regulations.

Engineering control methods to reduce hazardous exposures are preferred. Methods include mechanical ventilation (dilution and local exhaust), process or personnel enclosure, control of process conditions, and process modification (e.g., substitution of a less hazardous material). Administrative controls and personal protective equipment may also be required. Because of the high potential hazard associated with ammonia gas, stringent control measures such as enclosure or isolation may be necessary. For large-scale handling operations, use non-sparking, corrosion-resistant ventilation systems, approved explosion-proof equipment and intrinsically safe electrical systems in areas of use. For large-scale operations, consider the installation of a leak detection system with an alarm. Walls, floors, shelving, fittings, lighting and ventilation systems should be made from carbon steel, stainless steel or aluminium which do not react with ammonia. Supply sufficient replacement air to make up for air removed by exhaust systems.