Top 5 Things That Affects Your Gas Detector Readings
Gas detector accuracy can be affected by a variety of factors, which could lead to false alarms. In this blog, we’ll explore the Top 5 Things That Affects Your Gas Detector Readings, including exposure to alcohols, solvents, and cleaning products, cross sensitivity, environmental conditions, damaged or blocked sampling ports or filters, and not calibrating your detectors regularly.
1) Alcohols, Solvents, and Cleaning Products
Many common workplace chemicals, such as alcohols like ethanol or isopropanol, solvents like acetone or toluene, and various cleaning products, can interfere with gas detectors. These substances can trigger false alarms or cause temporary spikes in readings, even when dangerous gas levels are not present. Gas sensors detect target gases through chemical reactions or ionisation, and some chemicals, like alcohol vapours or strong solvents, can react with the sensor in a similar way, producing a reading that mimics the presence of combustible or toxic gases.
2) Cross Sensitivity
Cross sensitivity occurs when a gas detector responds not only to the target gas it is designed to measure but also to other gases in the environment. This can lead to inaccurate readings. Cross sensitivity is a natural limitation of many sensor types, particularly electrochemical sensors, which rely on chemical reactions to detect specific gases.
Certain gases are particularly prone to causing cross sensitivity due to their chemical similarities, which can significantly impact the accuracy of gas detector readings. For example, nitrogen dioxide (NO₂) sensors can react to ozone (O₃). Because ozone is highly reactive, it can trigger a NO₂ electrochemical sensor, causing elevated readings even when the actual NO₂ levels are low.
Chlorine (Cl₂) and chlorine dioxide (ClO₂) are another pair of gases that can interfere with each other’s detection. Electrochemical sensors designed for chlorine may respond to chlorine dioxide, and vice versa, because both gases share similar chemical reactivity. Chlorine (Cl₂) and sulfur dioxide (SO₂) can also cause cross sensitivity issues. Chlorine sensors may register a response when SO₂ is present, and SO₂ sensors may react to chlorine. This is particularly relevant in water treatment, chemical processing, or industrial cleaning settings, where both gases might be present in the same area.
3) Environmental Conditions
Gas detectors are designed to operate within specific environmental parameters, and conditions outside these ranges can affect sensor performance and the accuracy of readings. Extreme temperatures, for example, can slow the chemical reactions in electrochemical sensors or change the sensitivity of combustible gas sensors, resulting in readings that are either higher or lower than the actual gas concentration. Very low temperatures may reduce sensor responsiveness, while excessively high temperatures can accelerate sensor aging or temporarily trigger false alarms. Gas detectors are tested within a range of temperatures and will state what temperatures they can be used within on their technical specification.
High humidity or condensation can interfere with sensor operation, particularly electrochemical and PID sensors, by creating a thin film of water over the sensor surface or diluting the target gas. Very low humidity can cause some sensors to drift and produce inaccurate measurements over time.
4) Damaged or Blocked Sampling Ports or Filters
If a sampling port, hose, or filter becomes blocked the airflow to the sensor can be restricted, which may result in delayed or lower than expected readings. In some cases, the detector may fail to register the presence of a hazardous gas altogether, creating a potentially dangerous situation.
Filters are particularly important in protecting sensors from dust but if they become clogged or are not replaced regularly, they can impede gas diffusion. Sampling ports that are cracked, bent, or obstructed can prevent the correct volume of air from reaching the sensor. Even minor damage can affect the detector’s ability to respond quickly to changes in gas concentration, leading to inaccurate or unreliable data.
5) Not Calibrating Regularly
Gas detectors require regular calibration to ensure that their readings remain accurate and reliable. Over time, sensors can drift which means that the readings may no longer reflect the true concentration of gases in the area. Failing to calibrate a detector as recommended can result in readings that are either too high or too low, leading to false alarms or, more dangerously, missed detections of hazardous gases.
How to stop these things affecting your gas detectors performance
For alcohols, solvents, and cleaning products, it’s important to be mindful of where and when these chemicals are used. Using detectors in areas with strong vapours should be avoided when possible.
Cross sensitivity can be minimised by selecting the right sensor for the gases present in your environment and understanding which interfering gases may be present. Check cross-sensitivity charts. When purchasing a gas detector, the sales rep will inform you of any cross sensitivity.
Environmental conditions such as extreme temperatures, high or low humidity, or dusty and poorly ventilated areas can also impact readings. To reduce these effects, ensure detectors are rated for the conditions in which they will be used, and store and operate them within the manufacturer’s recommended ranges.
Damaged or blocked sampling ports and filters should be checked frequently. Routine inspection, cleaning, and replacement of filters and checking sampling ports for cracks or obstructions ensures that gas can reach the sensor correctly.
Following the manufacturer’s recommended calibration schedule and using the correct calibration gas ensures that any sensor drift is corrected, and readings remain reliable. Bump testing between calibrations can also help verify that detectors are responding correctly.
If you follow the above steps, your gas detector should be good for use without any of the problems mentioned above.
