Gas Monitoring Systems for Detection of Ammonia Exposure Levels and Applications

Ammonia (NH3) is pungent, colorless compound that is lighter than air. Anhydrous (water-free) ammonia is easily liquefied under pressure and is extremely soluble in water.

Because of its many applications, ammonia is one of the most highly produced inorganic chemicals, yet it is both caustic and hazardous. OSHA has set a limit of 25 ppm during an eight-hour shift. EPA regulations (40 CFR 68) require facilities with more than 10,000 pounds of ammonia to submit a risk management plan, including a hazard assessment, a prevention program, and emergency response program. An ammonia gas detection system should be an integral part of any ammonia risk management plan.

Ammonia is the precursor to most nitrogen-containing compounds. Virtually all synthetic nitrogen compounds are derived from ammonia, including nitric acid, which is used in the production of fertilizers, explosives, and many organo-nitrogen compounds. It is easily liquefied by compression or cooling for use in refrigeration and air-conditioning equipment.

Liquefied ammonia is stored in tanks, but if leaked into the ambient air, it will expand up to 850 times. This could lead to the formation of a white cloud which is very toxic. This points up the need for a reliable ammonia gas detection system that will alert personnel and can be connected to an existing control system.

MONITORING

There are several economical ammonia gas monitors on the market. Choose a simple “smart” ammonia gas detector designed for use in hazardous or classified locations. The best offer an industry standard 4-20 mA analog output signal and can be connected to any existing PLC, DCS, or EMS system.

HUMAN HEALTH EFFECTS OF AMMONIA GAS EXPOSURE

The effects of ammonia gas exposure can range from an irritation due to the odor
to life-threatening situation. This is why a reliable ammonia gas detection system is recommended in any large-scale application.
A recent tests has shown that 50 ppm or less for 5 minutes was not considered irritating to the eyes of volunteers, while exposure to 72 ppm was irritating to a few, and 134 ppm was irritating and caused tearing. At 700 ppm, the gas is immediately and severely irritating.
At 500 ppm, immediate and severe irritation of nose and throat occurs. Brief exposure to concentrations above 1,500 ppm can cause pulmonary edema, a potentially fatal accumulation of fluid in the lungs. The symptoms of pulmonary edema (tightness in the chest and difficulty breathing) may not develop for 1-24 hours after an exposure. Long-term respiratory system and lung disorders have been observed following severe short-term exposures to ammonia.
Furthermore, high levels of airborne ammonia gas will dissolve into moisture on the skin, forming corrosive ammonium hydroxide. At 10,000 ppm, ammonia is mildly irritating to moist skin. At 20,000 ppm, the effects are more pronounced and at 30,000 ppm, ammonia can produce chemical burns with blistering. These same exposure levels would be almost certainly fatal due to inhalation health effects.

EXPOSURE LIMITS

The Occupational Safety and Health Administration has set an ammonia exposure limit of 25 ppm during an 8-hour shift and a short-term limit of 35 ppm per 15 minutes. The Environmental Protection Agency (EPA). This is why a dependable ammonia gas detection system is invaluable in protecting workers.

APPLICATIONS

Ammonia has many industrial applications including the manufacture of:

Fertilizers

About 80% or more of the ammonia produced, either as ammonia salts or solutions, is used as fertilizer.

Refrigerants

Ammonia is an excellent refrigerant due to its favorable vaporization properties. Anhydrous ammonia is widely used in industrial refrigeration applications and skating rinks because of its low cost and high energy efficiency. Due to its toxicity, however, it is used less frequently in commercial applications, such as in grocery store freezer cases.

Geothermal power plants

The Kalina cycle, which is of growing importance to geothermal power plants, depends on the wide boiling range of the ammonia-water mixture. Ammonia gas detection is crucial in this environment.

Remediation of gaseous emissions

Ammonia is used in the scrubbing of SO2 that is created from the burning of fossil fuels. The resulting product, ammonium sulfate, can then be used as fertilizer. Ammonia similarly can be used to neutralize the nitrogen oxide (NOx) pollutants emitted by diesel engines.

Anti-microbial agent for food products

Anhydrous ammonia has been shown effective as an antimicrobial agent for animal feed and is currently used commercially to reduce or eliminate microbial contamination of beef.

Textiles

Liquid ammonia is used for treatment of cotton materials; gives properties like mercerization using alkalis. In particular, it is used for pre-washing of wool.

Pharmaceuticals and cosmetics

Either directly or indirectly, ammonia is a building block for the synthesis of many pharmaceuticals and cosmetics.