Gas detection equipment won’t last forever. Many sensors typically need to be replaced every two to three years as the components degrade over time. Cross-sensitivity to non-target gases can also lead to inaccurate results, including positive and negative readings.
Gas detection issues can lead to a false sense of security. These devices can malfunction for various reasons, leading to inaccurate readings and poor connectivity. All gas monitoring equipment naturally degrades over time, regardless of how often you use it. Exposing the unit to moisture, dirt, and high concentrations of gases only shortens its lifespan. You need to replace and maintain the individual components of the device to keep them working properly and the readings accurate. Other situations may require some guesswork as you determine why the instrument won’t respond. The gas detection troubleshooting process depends on the problem, age, and condition of your equipment.
Learn about some of the most common gas detection issues to keep your team safe on the job.
The Gas Detector Won’t Turn On
If the unit doesn’t respond or suddenly dies, there could be an issue with the power source. Make sure the device is set to the ON position.
For portable gas detectors, try swapping out the battery or recharging the unit. The battery will be disposable alkaline, rechargeable lithium-ion (Li-ion), or rechargeable nickel metal hydride (NiMH). Watch out for acid leaks and damage to the battery. Low temperatures can interfere with the voltage of alkaline batteries. Check the operating temperature range to see if the weather is causing the problem.
For fixed gas detectors, check the power cable for damage. Test the amount of voltage going into the device. If there’s no voltage, inspect the fuse connectors going in and out of the marshaling cabinet. Check the wiring inside the terminal block. There are usually three wires inside, which could be loose or in the wrong configuration.
A wireless gas detection system can help you stay on top of unexpected outages. You can see all the units in your network on the dashboard using the included software. The system sends you an alert as soon as a monitor goes offline.
The Gas Detector Won’t Calibrate
You need to bump test your gas detector before each shift and calibrate it if the bump test fails. Both are necessary to ensure your equipment is working properly, but the calibration process checks for accuracy and it isn’t the same for every type of device. Check the manufacturer’s guidelines for more detailed bump testing and calibration information, as well as calibration gas shelf life details. Various environmental factors, including humidity, temperature, and air pressure, can affect the readings on the device. Perform the test as close to the worksite as possible. Calibration gas can also expire, typically after three years or less depending on if they’re reactive or nonreactive gases.
Continue gas monitor calibration, according to the instructions, until the readings on the device match the known quantity of the gas tube. Don’t use a gas detector that fails to recalibrate properly. There could be a problem with the sensor.
Sensor Error and Replacement
The sensors on your gas detector have a service life. Most last up to two or three years before they need to be replaced, regardless of how much they’ve been used. Electrochemical sensors are made with precious metals and mineral acids that generate an electric current when exposed to the target gas. These materials will break down and lose accuracy over time. When replacing the sensor, let it stabilize in ambient air for up to three hours before calibrating it by hand.
Dirt and grime can also collect in and around the sensor housing. Use a brush or compressed air to get rid of any debris that could interfere with the signal. Clean out the sensor filter to let air pass over the sensor’s surface.
For fixed gas monitors, you can also try replacing the unit transmitter if replacing the sensor doesn’t do the trick. The first sensor may be usable with another transmitter.
Sensors can malfunction for other reasons. Moisture, humidity, and changing temperatures can affect how the sensor reacts to the target gas. Look for water near where the detection is installed. Sudden changes in the air may even cause the readings to fluctuate during operation. Electromagnetic interference (EMI) from radio frequencies, such as cellphone towers and communication networks, can trigger false positives by making the sensor more sensitive. This may not put your life at risk, but it can cause unnecessary panic among the crew and delay their response to an actual emergency if they believe it’s another false alarm.
The sensor may also be sensitive to other target gases in the air. The blending of certain gases can also affect the readings for a single target gas — also known as cross-sensitivity. Every manufacturer publishes a cross-sensitivity chart outlining how the presence of non-target gases can affect the readings on different types of gas sensors. Post this resource in the workplace or give each worker a copy they can carry around in their pocket. Teach workers how various gases can affect monitor sensitivity.
Investigating possible cases of cross-sensitivity usually requires some detective work. For example, a monitor may show positive readings for CO and H2S; however, there aren’t any in the atmosphere. Looking at the table may reveal that hydrogen cyanide (HCN) or H2 might be in the air because these gases tend to affect the readings on CO and H2S monitors.
If you get a negative reading on a gas monitor, don’t assume the equipment is broken. This usually means the sensor either needs to be recalibrated or another gas is causing the ions in the sensor to react negatively, which reads as a negative percentage. Learning cross-sensitivity is a crucial part of the training process. A slight change in accuracy can change your perception of the work environment and provide a false sense of comfort.
Gas detection equipment isn’t an exact science. Various factors can affect the readings on your equipment, which could cause workplace delays. However, learning how to troubleshoot gas detection problems helps you get as close to a perfect reading as possible.
An error can occur at any time, delaying your workday. If there’s something wrong with the device, the worker should report the issue to their supervisor and stop working until the problem is resolved. Everyone should keep this information in mind when inspecting their gas detection equipment. The crew should have time to double-check the readings on the device before starting their shift.
Contact PK Safety for gas detector calibration services and gas detection troubleshooting to get your equipment in working order.