Carbon Monoxide Sensors

What’s the difference between the following Carbon Monoxide (CO) sensor names; CO, CO high and dual CO/H2S?

Carbon Monoxide (CO) poses a big threat to workers carrying out their jobs in environments where toxic CO gas might be present. CO sensors are found in gas detectors used by workers to protect themselves against the dangers posed by CO. Not all CO sensors are the same. While most CO sensors are based on the same electro-chemistry, there are many different types of CO sensors.

Understanding the different types and the specific advantages and disadvantages of each sensor types are critical to selecting the right CO sensor for your application.

The standard CO sensor is the most commonly used CO sensor type. While it will measure CO and usually includes a Hydrogen Sulphide (H2S) filter to eliminate H2S cross-interference, it is vulnerable to cross-interference from other gases, most notably Hydrogen (H2). When using the standard CO sensor, consider the likelihood of other gases being present in the facility that might interfere with this sensor’s readings.

Another thing to consider is the sensor’s measuring range. A standard CO sensor measures up to 1,000 or 1,500 ppm (parts per million), which might not be high enough for mine and rescue applications or the steel industry. This leads us onto the CO high range sensors.

The CO high or CO high range sensor is more commonly used in industries such as mining or mine rescue and steel. Rather than the typical measuring range of 1,000 or 1,500 ppm, this sensor is capable of measuring Carbon Monoxide up to concentrations of 9,999 ppm.

The dual CO/H2S sensor is commonly used to detect for CO. This sensor is a combination of both a Carbon Monoxide sensor plus a Hydrogen Sulphide sensor, with both sensors being built into a single housing.

The dual CO/H2S sensors are commonly used to detect for four gases using three sensor slots or to detect for six gases using five sensor slots. While this is extremely convenient and helpful in achieving smaller size gas monitors, remember that since this sensor must allow both gases to diffuse into it, it will not include the H2S filter. In this instance, there is a trade-off between gas detector size and the sensor’s cross-sensitivity to H2S.

There are three considerations when choosing a CO sensor;

  1. Your application
  2. Your CO gas levels
  3. The potential background cross-interfering gases that could be present.

If you’re still in doubt about which CO sensor to use, talk to a1-cbiss. We can help make the best recommendation for you and your application.