What is the difference between infrared sensor and catalytic combustion sensor?
When monitoring combustible gases and flammable vapors, sensors play a key role, including catalytic sensors and infrared (IR) sensors. The environment, response time and temperature range are just factors to consider when deciding which technology to use is best.
So, what is the difference between a catalytic sensor and an infrared (IR) sensor? Why do these two technologies have their pros and cons, and how do you know which method is best for different environments?
Infrared sensor technology is based on the following principle: infrared (IR) light with a specific wavelength will be absorbed by the target gas. Usually there are two transmitters in the sensor, which generate infrared beams: a measuring beam with a wavelength that will be absorbed by the target gas and a reference beam that will not be absorbed. Each beam has the same intensity, and is deflected to the light receiver by a mirror inside the sensor. In the presence of the target gas, the intensity difference between the reference beam and the measurement beam will be used to measure the concentration of the gas present.
In many cases, infrared (IR) sensor technology has many advantages over catalytic combustion technology, or is more reliable in aspects that may damage the performance of catalytic combustion sensors (including low oxygen and inert environments). Only the infrared beam interacts with the surrounding gas molecules, so that the sensor has the advantage of not facing the threat of poisoning or suppression. Infrared technology provides fail-safe testing. This means that if the infrared beam fails, the user will be notified of the failure.
Infrared sensors are very suitable for the oil and natural gas industry, and can detect methane, pentane or propane in explosive low-oxygen environments, and catalytic combustion sensors in these environments may encounter difficulties.
However, IR sensors are not perfect because they can only output the target gas linearly. If the infrared sensor responds to other flammable gases, the target gas will be non-linear. Just like catalytic combustion sensors are prone to poisoning, IR sensors are also prone to severe mechanical and high temperature shocks, and are also strongly affected by pressure changes.
In addition, infrared sensors cannot be used to detect hydrogen, so we recommend using catalytic combustion or semiconductor sensors in this case. The primary goal of safety is to select the appropriate detection technology to minimize the hazards in the workplace. We hope that by clearly identifying the differences between these two sensors, we can improve people's awareness of how to maintain safety in various industries and hazardous environments.
Comparison of infrared sensor and catalytic combustion sensor
Catalytic combustion sensor
Catalytic combustion gas sensor is a device used to detect combustible gas or flammable vapor entering the explosion range to warn of rising gas concentration levels.
The working principle of the sensor is a circle of platinum wire with a catalyst inside to form a small active bead, which can reduce the temperature at which the gas ignites around it. When combustible gases are present, the temperature and resistance of the beads increase relative to the resistance of the inert reference beads. The resistance difference is measured so that the concentration of the gas present can be measured. Due to the presence of catalysts and beads, catalytic combustion sensors are also called catalytic or catalytic bead sensors.
The catalytic sensor was originally created by British scientist and inventor Alan Baker in the 1960s, and the catalytic combustion sensor was originally designed for the long-term use of flame safety lights and Canary technology. Today the equipment is used in industrial and underground applications such as mines or tunnels, oil refineries and oil rigs.
Compared with IR sensors, the cost of catalytic combustion sensors is relatively low due to the difference in technology, but they may need to be replaced more frequently. In the case that the linear output corresponds to the gas concentration, the correction factor can be used to calculate the approximate response of catalysis to other flammable gases. When there are multiple flammable gases, catalysis can be a good choice.
The fixed detector probe with built-in catalytic sensor outputs mV bridge signal, which is very suitable for installation in hard-to-reach areas; debugging and calibration can be carried out through the controller panel. On the other hand, since catalytic combustion requires oxygen during the working process, it is difficult to cope with catalytic combustion in an environment with low or little oxygen content. For this reason, confined space instruments containing catalytic combustion type combustible gas alarms usually also need to include a detector for measuring oxygen. In an environment where the compound contains silicon, lead, sulfur, and phosphate, the sensor is easily poisoned (irreversible reduction in sensitivity) or suppressed (reversible reduction in sensitivity), which may cause harm to people in the workplace. If exposed to a high concentration of gas, it may damage the catalytic combustion sensor. In this case, catalytic combustion will not "fail safe", which means that no notification will be issued when the gas is detected and the instrument malfunctions. Any failure can only be determined by a bump test before each use to ensure that the performance will not decrease.
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