What Are the Common Problems and Usage Misconceptions of Gas Detectors?
The topic of using gas detectors has gained a lot of attention. Today, we have collected and summarized some common questions and misconceptions about their use. Here are the answers to these questions:
1. What are the potential gas (liquid) hazards in firefighting and rescue environments?
Answer: (1) The hazards of oxygen:
When the oxygen concentration exceeds 23%, some substances can cause combustion, and it is intense combustion. Combat uniforms can also burn in air with high oxygen content and do not provide any protection. When it exceeds 70%, it will cause harm to the human body, resulting in "oxygen" poisoning;
When the oxygen concentration is below 12%, people's judgment will be lost, breathing will become difficult, and symptoms such as purple lips will appear. When it is below 10%, vomiting, immobility, loss of consciousness, and even death may occur.
(2) The hazards of toxic gases (liquids):
Gases, vapors, and smoke (such as hydrogen sulfide, sulfur dioxide, carbon monoxide, chlorine gas, ammonia gas, organic gases).
(3) The hazards of flammable or explosive gases:
Excessive concentrations of gas, steam, or dust can cause combustion or explosion.
2. What types of gas detectors can be classified based on their working principles?
Answer: Listening: Ultrasonic, infrared acoustic;
See: Image category;
Wen: Catalytic combustion, electrochemistry IR/Laser,PID.
3. What is the principle of detecting oxygen and toxic gases?
Answer: Electrochemical sensors, also known as current gas sensors, are equipped with electrolytes and positive and negative electrodes inside the sensor. When a specific gas enters, it will be absorbed through the thin film, causing oxidation or reduction reactions inside. The current changes, and the gas concentration can be determined by measuring this current.
Attention: Some sensors require a bias voltage between the electrodes, and most toxic gas sensors require a small amount of oxygen to maintain normal function. High humidity and high drought can affect the service life of the sensor, and instantaneous pressure changes may cause false alarms.
4. What is the principle of detecting flammable gases?
Answer: Combustible gases (methane, LPG, propane, hydrogen, acetylene) can be detected based on the principle of catalytic combustion.
Catalytic combustion sensors belong to high-temperature sensors. The detection element of the catalytic component is formed by wrapping aluminum oxide and adhesive on a platinum wire coil (φ 0.025~φ 0.05) to form a spherical shape, and applying current to the platinum wire to maintain high temperature (300~400 ℃) of the detection element.
At this point, if in contact with combustible gases such as methane gas, methane will burn on the catalyst layer, and the essence of combustion is the reaction between methane adsorbed on the surface of the component and adsorbed oxygen ions.
Attention: There should be sufficient oxygen in the detection environment. In an oxygen free environment, this detection method cannot detect any flammable gases.
