What are the common problems and usage errors of gas detectors
The topic of using gas detectors has attracted everyone's attention to a certain extent. Today, we have collected and summarized some commonly asked questions and some misconceptions about their use. Now, we have summarized the answers to these questions as follows:
1. What are the potential gas (liquid) hazards in firefighting and rescue environments?
Answer: (1) Hazards of oxygen:
When the oxygen concentration exceeds 23%, some substances can cause combustion, which is severe. Combat suits can also burn in air with high oxygen content and do not provide any protection. When it exceeds 70%, it can cause harm to the human body and cause "oxygen" poisoning;
When the oxygen concentration is below 12%, people's judgment will be lost, breathing will become difficult, and symptoms of purple lips will occur. When it is below 10%, vomiting, inability to move, loss of consciousness, and even death may occur.
(2) Hazards of toxic gases (liquids):
Gases, vapors, smoke (such as hydrogen sulfide, sulfur dioxide, carbon monoxide, chlorine, ammonia, organic gases).
(3) Hazards of flammable or explosive gases:
High concentrations of gas, steam, or dust can cause combustion or explosion.
2. What are the types of gas detectors that can be classified based on their working principles?
Answer: Listening: Ultrasound and infrared acoustics;
Look at: Imaging class;
Smell: Catalytic combustion, electrochemistry, IR/Caser, PID.
3. What is the principle of detecting oxygen and toxic gases?
Answer: Electrochemical sensors, also known as current gas sensors, are equipped with electrolyte and positive and negative electrodes inside the sensor. When a specific gas enters, it will be absorbed through the thin film, and oxidation or reduction reactions will occur 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 lifespan of the sensor, and instantaneous pressure changes may cause false alarms.
4. What is the principle of detecting combustible 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, and the detection element of the catalytic element is located in a platinum wire coil（ φ 0.025~ φ 0.05) Wrap with aluminum oxide and adhesive to form a spherical shape, and apply current to the platinum wire to keep the detection element at high temperature (300-400 ℃).
At this point, if it comes into contact with combustible gases such as methane, methane will burn on the catalyst layer, and the essence of combustion is the reaction between the adsorbed methane on the surface of the component and the adsorbed oxygen ions.
Attention: There should be sufficient oxygen in the detection environment. In an oxygen free environment, this detection method cannot detect any combustible gases.
