Introduction to Ammonia (NH3)

Ammonia (NH3) is a colorless gas with a characteristic pungent, suffocating odor. Widely used in industry and commerce, it is used in fertilizers, food processing, refrigerants, pharmaceuticals, and cleaning products. Ammonia also exists naturally in the environment, where it is produced from the decomposition of organic matter, including plants, animals, and animal waste.

Although it is widely used in different industries, ammonia is caustic and hazardous. The widespread use of ammonia in industrial and commercial locations increases the risk of exposure through accidental release. If the ammonia is under pressure, the gas will rapidly release into the air and quickly fill up an enclosed area. The release of Ammonia has the potential for harmful effects on workers and the public if it is not monitored correctly.

Health Hazards

When present in high concentrations, ammonia may produce these symptoms:

  • Coughing
  • Nose, throat, respiratory irritation
  • Fatigue
  • Chest tightness, pain
  • Blindness
  • Death

Exposure Limits

When researching NH3 gas detection solutions, facility managers should be aware of the following NH3 exposure limits:

Exposure Limits Agency
50 ppm TWA OSHA PEL (General Industry)
50 ppm TWA OSHA PEL (Maritime)
25 ppm TWA, 35 ppm STEL ACGIH TLV
25 ppm TWA, 35 ppm STEL NIOSH REL
300 ppm NIOSH IDLH

Technology for NH3 Gas Detection

Electrochemical Sensors

Electrochemical sensors are fuel cell-like devices consisting of an anode, cathode, and electrolyte. The components of the cell are selected so that a subject gas, allowed to diffuse into the cell, will cause a chemical reaction and generate a current. The cells are diffusion-limited, meaning that the rate of the gas entering the cell is solely dependent on the gas concentration. The current generated is proportional to the rate of consumption of the subject gas in the cell.

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Solid State (Semiconductor) Sensors

Solid state (semiconductor) sensors have a resistance that is affected by oxygen adsorbed on the surface of the sensor. Oxygen atoms capture electrons on the semiconductor surface, thereby increasing its resistance. The sensors can be impregnated with dopants such that the sensor's resistance changes when specific gases displace the adsorbed oxygen.

Learn more about the advantages of using Sierra Monitor's solid state gas sensor modules »