Thousands of flammable and toxic gas sensors are in use globally every day. The increased use and availability of gas detection instruments is a positive step towards increased safety by reducing the risk and incidence of gas exposure.
This increase in the number of gas detection instruments though, creates a potential opportunity for complacency in the proper selection of these life saving devices.
Far too often colour, shape and size are deemed more important than the technical capabilities of the instrument to meet the customer’s requirements.
Ergonomics is important, but not as important as technical performance.
Gas Detector Selection: The Sensor is at the Heart
The most important technical aspect of all gas detectors is the heart of the instrument – the sensor. All the bells and whistles that can be crammed into one instrument can’t take away from the simple fact that sensors must technically process incoming gases and vapours and provide an accurate response.
The majority of sensors today are catalytic pellistors , semi-conductor and thermal conductivity for combustible gases, electrochemical for toxic and oxygen. Infrared have become more widely used for CH4 and CO2 today and PID for VOC’s but the bulk of the sensors are catalytic and electrochemical.
All sensors have their positive and negative attributes. Selection of the correct sensor needs to be based upon evaluating your specific application.
Which Sensor Should I Choose?
Each sensor has its own characteristics and capabilities. Sensor manufacturers develop dozens of different sensors for the same gas type. Gas detector manufacturers use different sensors for different instruments.
Sensor Selection factors:
- The working environment- how will this impact the sensor.
- What contaminants will be introduced through work activities.
- How will the sensors are handled and maintained.
Your environment is unique to you which is why you must determine if anything in your environment could negatively impact the performance of your instruments prematurely. For example: did you know that H2S is an inhibitor to catalytic combustible gas sensors? Loss of sensitivity is dose dependent and the impact may vary from immediate to many years, but the fact is, H2S affects these sensors. If overlooked sensor performance at a minimum can occur and worst case failed sensors put workers at risk.
Before you purchase your gas detection device, you must gather all the facts about your environment so you can get the correct technical information on each manufacturer’s sensor capability.
18 Questions For Gas Sensor Selection:
All of these variables can impact the accuracy, efficiency, performance and longevity of your sensors and therefore, your gas detector.
By evaluating the working environment, critical detail can be used to evaluate potential gas detectors and to develop a long term maintenance and calibration program.
- What are the actual gas hazards that you need to monitor?
- What is the typical background gas levels for gas hazard?
- Where is the source of the hazard?
- Are the concentrations higher in those areas?
- Do you encounter spikes in gas concentrations from time to time?
- How high and how often?
- Would you potentially over range a combustible gas sensor?
- How often?
- Are there interfering gases that will affect readings (positively or negatively) for each sensor type?
- If yes, how will the sensors respond?
- How will that affect you and your workers in the workplace?
- Can you use a positive response to your benefit?
- What poisons or inhibitors are present that could impact your combustible gas senor?
- How will that impact the sensor?
- What other contaminants are in the atmosphere? Particulate, frequency, other? What is there impact?
- Will you introduce a new gas hazard with your work activity?
- How will that gas hazard affect the sensors?
- What is the impact of your analysis on your calibration and bump testing procedures?
As you can see, selecting the right gas sensor isn’t easy. If you need some help or advice feel free to ask us a question.