Portable Toxic Gas detector Introduction Series – Part 4
- Besides the standards for measuring, detecting and detecting toxic gases have been studied and published. Handheld gas detectors for the need to detect toxic gases also flourish. For gas detectors, gas purifiers, the basic nuclear is the sensors integrated inside the machine. Many sensor manufacturing technologies have been born and developed to suit different types of gas measurement applications. Here’s a brief presentation of a handful of those technologies.
Part 4 – Some types of gas measuring sensors
Electrolysed Gas Measurement Sensor
- Electrolytic gas detectors work by allowing gases to diffuse through a permeable membrane to reach an electro pole, where the gas will be oxaized or eliminated.The generated current is determined by the amount of oxidized gas on the electrolye, which in turns out the concentration of the gas. Manufacturers can optionally measure different gases by changing the diaphragm to allow detection of concentrations of a variety of gases. In addition, with a mechanical/physical diaphragm, gas detectors tend to be more stable and reliable and therefore require less maintenance than other early detection technologies.
- However, these gas measurement sensors depend on corrosion factors or chemical contamination and may only last between 1 and 2 years before having to be replaced.Electrolytized toxic gas detectors are used in a wide range of environments such as refineries, gas turbines, chemical plants, underground gas storage facilities …
Infrared Gas Sensor
- Infrared point sensors use radiation through a known amount of gases; the energy from the sensor’s emits is absorbed at a certain wavelength, depending on the nature of the specific gases. For example, CO absorbs wavelengths from 4.2 – 4.5 μm. The energy in this wavelength is compared with an external wavelength of the absorption range, the difference of energy between the two wavelengths is proportional to the concentration of the current gas.
- This type of sensor has the advantage that it does not need to be placed in a gas-containing environment for detection and therefore it can be used to detect gases remotely. Infrared point sensors can be used to detect hydrocarbons and other positive gases with infrared such as steam and CO2. Common infrared sensors are used in wastewater treatment plants, refineries, gas turbines, chemical plants, and other facilities where flammable gases are present and the possibility of an explosion exists. Remote gas detection capabilities allow monitoring in large spaces.
- Engine emissions are another area where IR sensors are being studied. The sensor can detect high levels of carbon monoxide or other abnormal gases in the exhaust pipe of the vehicle and can even integrate with the vehicle’s electronic system to notify drivers
Semiconductor Gas Measuring Sensor
- Semiconductor sensors detect gases with a chemical reaction that will take place when the gas enters direct contact with the sensor. Tin dioxide is a commonly used material used in semiconductor sensors, and the sensor’s appeal is reduced when it enters contact with the monitored gas. Tin dioxide’s power is usually around 50kΩ in the air but can be reduced to 3.5kΩ if there is the appearance of 1% Methane. The change of the edic is used to calculate the concentration of gases. Semiconductor sensors are often used to detect Hydrogen, Oxygen, alcohol vapor and toxic gases such as CO. One of the most common uses of semiconductor sensors is carbon monoxide. They are also used in measuring alcohol content. Because sensors need to go into contact with gases to detect them, therefore semiconductor sensors work in smaller distances than infrared and ultrasonic sensors.
by TES Industry