Combustible Gas Detection

Common Instruments and Industries

Combustible gas detection instruments detect the presence of combustible, flammable, toxic, and oxygen altered gases in the environment, minimizing the chance of a gas leak reaching explosive and/or life-threatening levels. 

How Do They Work?

A combustible gas detector measures the concentration of specific gases in a certain area using infrared, ultrasonic, electrochemical, or semiconductor sensors. Once a reference scale is established for the system, the measured concentration of the environment is then compared to it to determine if the environment is still safe for all personnel or if it’s experiencing a change within. Once the sensor detects a concentration beyond levels preset to be safe, it will alarm users and workers via sound alarm, light, or a combination of signals for warning. 

Types of Combustible Gas Detectors

There are two types of combustible gas detectors: passive and active. Passive detectors most commonly found in catalytic bead or electrocatalytic systems. This type of device can be found in a variety of industries as a single-point detection system for gases like hydrocarbons. Functionality is simple and reliable with the idea that a combustible gas can be oxidized to result in heat. The temperature change is converted to a sensor signal, activating alarms to start the process of fire prevention. While the sensors in passive devices are not the most fragile, they do need to be maintained to perform optimally. 

Active detectors measure gas concentrations through the absorptions of infrared (IR) radiation at specific wavelengths as it passes through a volume of gas. Devices using the technology have a light source and light detector to measure the light intensity and the two specified wavelengths. Both wavelengths are absorptive, with one being active and the other being referenced. If a volume of gas passes between the source and the detector, the amount of light in the active wavelength sensed in the detector is reduced while the referencing wavelength remains the same. The gas concentration of the leak source is then determined from the relative difference between the two signals. Active detectors are considered “active” because the IR source transmits a signal multiple times a second and the amount of energy falling on the sensor is an active measure of the gas concentration in that specific moment. Sensors for active systems are very fragile and need immediate maintenance. Active detectors can be used for single or line of sight applications, depending on your requirements.  

Flammable Gases for Combustible Gas Detection

Flammable gases ignite when in close contact with a heat or flame source. The most common gases for this scenario are acetylene, ammonia, hydrogen, and liquefied petroleum gas (LPG). Each already has its own safety concerns when workers are exposed to specified concentrations and can be more complex with properties such as colorless and odorless. Some of the gasses such as acetylene and ammonia have narrow flammability ranges, making explosions and fires less likely but still possible. Hydrogen and LPG gas leaks have higher flammability ranges, making the risk greater if exposed to a heat source with a wider concentration range. 
Combustible gas detection systems are valuable across a variety of industries. Some of the most common industries to find these devices include welding shops, nuclear plants, wastewater treatment plants, and industries with confined spaces. Otis Instruments has a vast selection of Wired and WireFree easy-to-use, robust, and configurable gas detectors and monitors capable of detecting both toxic and non-toxic gases for diverse applications. For more information regarding gas detection systems, visit our products page. To learn more about combustible gas detection, or other solutions for your industry, contact Otis Instruments today!

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