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Market Overview – There are three types chemicals used in refrigeration systems today – ammonia (NH3), carbon dioxide (CO2), and Freons.  Ammonia is the predominant chemical, particularly in larger facilities.  Carbon dioxide is a newer chemical being used in conjunction with ammonia systems – it is considered less hazardous than ammonia and also can be used for lower temperatures.  Freon is used in older, typically smaller, applications, and is being phased out as it is both expensive and an environmental hazard.

Leak Detection/ambient monitoring

• “Normal” ambient monitoring for leaks – measurement around compressors/engine rooms and around lines/tanks
  • For NH3, an electrochemical ammonia sensor that can measure high levels in ppm.
  • For CO2, Infrared detectors are the best choice. Oxygen sensors can also be used for oxygen deficiency (oxygen being displaced by CO2). Since CO2 is heavier than air this must be taken into account when designing a system/monitoring strategy – often times mounting oxygen transmitters low creates issues with them being damaged..
  • For Freons, the sensor technologies used are either semiconductor sensors or pyrolizers, depending on the Freons that need to be measured.
• “Catastrophic” / Environmental release monitoring - typically a vent-line roof application
  • For NH3, the best choice is an LEL sensor that can measure high levels in % (an electrochemical sensor in this application will be saturated and used up almost instantly in these high level concentrations)
  • For CO2, infrared detectors.
  • For Freons, semiconductor sensors.

Personal Monitoring – personnel working near bottling lines, fill lines, packaging lines, and in cold storage warehouses.

• For NH3, the best choice is an electrochemical ammonia sensor that can measure in low levels in ppm.
• For CO2 and Freons, the best choice is an oxygen sensor measuring in the breathing zone.

Special Considerations

• Many of these applications are in food areas subject to wash downs and rapid, large temperature swings.  Sensors that can remain stable in temperature swings, as are designing systems to deal with high humidity, are critical considerations in insuring that the system will function properly.  For example, freezers can go from -40 F to 70 F in 20 minutes followed by high pressure steam cleaning.

• Trying to do both personnel monitoring and leak detection with the same instruments is a poor strategy. Personal monitoring is best accomplished with small clip-on detectors, leak detection is best accomplished with area monitors.
• Photoionization detectors can be used for portable leak detection of ammonia as they have broad ranges (typically 1 – 2000 ppm) and can’t be over-ranged/damaged like an electrochemical sensor, but cross-sensitivity to other chemicals has to be considered.

Our solutions: We can work with you to design and install a comprehensive refrigerant monitoring system without the problems associated with many of the systems on the market - short sensor life, false alarms due to drift and an inability to adjust to temperature swings, and low maintenance/calibration costs.

Polytron 7000                       NH3 LC sensor   

PIR 7000 CO2 

DTF 994                  Polytron 7500

Single gas O2 instruments PIDs