How to Prevent the Sensitivity of Combustible Gas Detectors from Being Affected in High-Temperature Environments?
High temperature is a common state in the production scenarios of petrochemical reaction plants, metallurgical furnaces, and energy and power steam pipelines. As a "safety sentinel" for preventing gas leaks and avoiding explosion accidents, combustible gas detectors are prone to sensitivity degradation when exposed to high temperatures for a long time. Once the detection is inaccurate, it not only fails to timely warn of risks, but may also pose hidden dangers to production safety. So, how does high temperature affect the sensitivity of combustible gas detectors? What methods should the staff use to prevent it?
1, First understand: how high temperatures can reduce the sensitivity of detectors
The influence of high temperature on the sensitivity of combustible gas detector is mainly related to the type of sensor. Different sensors are subject to different mechanisms of high temperature interference, but the detection accuracy will eventually decline.
For example, commonly used catalytic combustion sensors rely on catalysts to promote the oxidation reaction of combustible gases to generate detection signals. In high temperature environments, the activity of catalysts will significantly decrease, and even "poisoning" phenomena may occur, resulting in slower reactions to combustible gases. Not only will the detection signal be distorted, but there may also be response delays; Infrared sensors, on the other hand, rely on stable light sources and detectors to operate. High temperatures can cause the light source's luminous intensity to be unstable, and the detector's signal reception ability can also be affected. This can easily lead to false alarms (alarms even when not exceeding the standard) or missed alarms (no response when actually exceeding the standard), and in severe cases, the sensor may even be directly damaged, completely losing its detection capability.
2, Here are four tips to prevent high temperature from affecting sensitivity
To maintain stable sensitivity of combustible gas detectors in high-temperature environments, it is necessary to start from multiple aspects such as hardware, installation, selection, and linkage protection. Specific measures can refer to these four:
1. Hardware level: Add protective shields to instruments
One is to install a temperature compensation circuit. Many professional combustible gas detectors have built-in circuits that, through specific algorithms or hardware designs, monitor real-time changes in environmental temperature and automatically cancel out the interference of temperature fluctuations on the detection signal. For example, when the temperature rises, the circuit will adjust the signal amplification factor to keep the detection result within an accurate range and avoid reading deviation caused by temperature.
The second is to strengthen the heat dissipation design. The casing of the combustible gas detector should be made of metal with good thermal conductivity, or heat sinks and small fans should be installed around the sensor to accelerate heat dissipation; Some detectors designed for high temperature scenarios will also use internal airflow ducts to allow air to circulate and remove heat, ensuring that the sensor's operating temperature is always maintained within the rated range (usually -20 ℃~50 ℃, and high temperature resistant models can reach over 100 ℃), without performance degradation caused by high temperature "baking".
2. Installation environment: Avoid high temperature sources and ensure proper insulation
The installation location should prioritize avoiding high-temperature sources, such as boilers, heating furnaces, steam pipelines, etc., and maintain a distance of at least 1 meter from these high-temperature objects; If it is really impossible to stay away (such as near the furnace), insulation treatment should be done by wrapping the detector shell with high-temperature resistant insulation material (such as ceramic fiber cloth), or installing sunshades and insulation panels above the instrument to reduce direct high-temperature radiation; Ventilation ducts can also be installed in the installation area to lower the local ambient temperature through flowing air, creating a relatively cool working environment for the detector.
3. Selection and maintenance: Choose the right instrument and perform regular maintenance
When selecting, it is necessary to choose high-temperature resistant models with targeted selection. If it is a scenario such as a kiln or metallurgical workshop with a long-term temperature exceeding 80 ℃, a dedicated combustible gas detector labeled as "high temperature resistant" can be directly selected. The sensors and circuits of such instruments have been specially treated to withstand temperatures of 100 ℃ or even higher, and will not easily fail due to high temperatures.
We need to shorten the calibration cycle in terms of maintenance. Under normal temperature conditions, the detector may be calibrated once every 1-2 years, while under high temperature conditions, it is recommended to calibrate every 3 months. By using the sensitivity of the standard gas detection instrument, deviations can be corrected in a timely manner; At the same time, regularly check the aging condition of the sensor, such as checking whether the output signal of the sensor is stable. If the signal fluctuates greatly or the response slows down, it is necessary to replace the sensor in a timely manner to avoid inaccurate detection caused by the aging of the sensor and the influence of high temperature.
