For many refrigeration applications, using solid state sensors will provide an economical and reliable gas detection solution. Solid state sensors are reliable if used in a clean area with very little temperature and humidity changes. Solid State refrigerant sensors should not be used where there are other chemicals or gases present (other than refrigerants), such as alcohol based cleaners, fumes from running engines, fuel storage containers, etc.

Using infrared sensor technology will ensure the highest degree of sensor accuracy if monitoring an area where there are other  contamination gases or multiple refrigerants in the same area. Infrared refrigerant sensors should not be used in locations that have corrosive chemicals such as chlorine, ammonia and other oxidizers that are present, especially if there is a higher humidity level.

Comparison of CET’s Solid State Refrigerant Sensors and Infrared Refrigerant Sensors

  Solid State Refrigerant Sensors Non-dispersive Infrared Refrigerant Sensors
Mode of Operation Metal oxide changes resistance in response to the presence of target gas. The change is measured by the electronics of the detector to determine the gas concentration. Gas molecules absorb the infrared light of the optical sensor at a certain wave length. The wave length is measured by the electronics of the detector to determine the gas concentration.
Specific Refrigerant Gases Detected in CETCI Gas Detectors R22, R134A, R402A, R404A, R407C, R410A, R422D, R438A, R507A R22, R32, R123, R134A, R404A, R407A, R407C, R407F, R410A, R427A, R448A, R449A, R507, R422A, R422A, R452A, R513A, HFO1234YF, HFO1234ZE, FO1233ZD
Output Non-linear Linearized
Gas Detection Range (gas dependant) 0 – 2,000 ppm 0 – 3,500 ppm (0 – 1,000 ppm for R123)
Sampling Method Diffusion Diffusion
Life Expectancy 5 to 7 years    7 to 10 years
Maintenance Low Low
Calibration Less calibration frequency required, every 12 months recommended.

Establish and maintain zero point and the accuracy of the detector remains intact. Less calibration frequency required, every 12 months recommended.

Sensitivity High, detects low gas concentrations High, detects low gas concentrations

Accuracy (gas dependent)

±15% ±5% (if calibrated to specific refrigerant)
Response Time T90 < 2 minutes (target refrigerant dependent) < 5 minutes
Drifting/Aging Susceptible to temperature and humidity changes, require regular calibration to compensate for drift/aging Less susceptible to temperature and humidity changes, little drift, moderate aging
Operating Temperature -20°C to 40°C (-4°F to 104°F) -30°C to 40°C (-22°F to 104°F)
Response to Temperature Changes Sensitive to changes in temperature Short term response to large changes in temperature
Operating Relative Humidity 15 - 90% RH non-condensing 5 - 90% RH non-condensing
Response to RH Changes Sensitive to changes in humidity High humidity can affect response and promote corrosion.
Wet Environments Will shorten lifespan Water or vapour condensation can impair the optics ability to function.
Dry Environments Must be calibrated in the environment it will be operating in. No problem in dry environments
Dirty, Dusty Environments Will shorten lifespan and requires calibration more often. Dust and dirt can coat the optics and impair the sensor response.
Time Required to Stabilize New sensor is stable after 3 minutes; old sensor (ie. 5 yrs) may take 5 minutes. Typically requires 10 to 20 minutes to equalize after a sudden variation in temperature. May take up to 30 minutes to stabilize from a change in humidity.
Presence/Absence of Oxygen (Air) Requires oxygen for proper functioning. No minimum level of oxygen required; operates in the absence of, or enriched presence of oxygen.
Cross Contamination Non-specific, sensitive to many other gases, vapours and chemicals, susceptible to false alarms Can be configured for broad range or gas specific, few false alarms. Cross sensitivity to other refrigerants.
Exposure to High Concentrations of Gas (poisoning) Moderately resistant to poisoning Will not burnout, immune to poisoning. May require a long time to clear before accurate readings can be taken again.
Continuous Exposure to Gas Sensor reading will become unreliable after 15 minutes (will read higher than calibrated value). Does not affect operation
Power Consumption High High
Cost Economical Can be expensive



 Applications for Refrigerant Sensors: Recommendation by Sensor Type

Application Sensor Type Reason
Boiler / Machinery Rooms IR No false alarms, longer life span, less maintenance
Breweries IR No false alarms, longer life span, less maintenance
Chiller Rooms IR No false alarms, longer life span, less maintenance
Convenience Stores SS IR too expensive
Hotels SS Requires a small remote sensor on a cable for rooms with air conditioners
Shopping Malls IR No false alarms, longer life span, less maintenance
Supermarkets IR No false alarms, longer life span, less maintenance
Universities IR No false alarms, longer life span, less maintenance
Office Buildings IR No false alarms, longer life span, less maintenance
Hospitals IR No false alarms, longer life span, less maintenance


NOTE: Ammonia is commonly used as a refrigerant in very low temperature applications such as food/meat processing, ice making plants and ice arenas. Electrochemical sensors are required to ensure accurate monitoring in Ammonia applications.
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Applications for Refrigerant Sensors, Recommendation by Sensor Type

refrigerants-applications

 

 

 

 

 

 

NOTE: Ammonia is commonly used as a refrigerant in very low temperature applications such as food/meat processing, ice making plants and ice arenas. Electrochemical sensors are required to ensure accurate monitoring in Ammonia applications.

For more information about our products, check out our website at www.critical-environment.com or to discuss a tailored gas detection solution for your application, contact us at 1-877-940-8741.