Choosing the right gas sensor for your fixed detection system involves a number of considerations, especially when detecting methane gas. Between the different types of sensors on the market, there are two different technologies to consider: infrared and catalytic bead.
While catalytic bead sensors have been in use for many years, infrared sensors are gaining popularity due to their increased reliability and longer life. Understanding the differences between these two major technologies is important as you determine how to configure your gas detection system. In the case of methane gas, it’s crucial to have a sensor you can rely on in your specific environment.
What is Methane Gas?
Did you know that natural gas is made up of nearly 87% methane? Like other combustible materials, methane gas is highly flammable and presents a huge risk for those dealing with natural gas. In its organic state, it is odorless, colorless, tasteless, and nontoxic. As a major greenhouse gas, it is produced during the anaerobic decomposition of manure or in the production of chemicals such as acetylene and methanol.
As a component of natural gas, it is known to rise and accumulate in certain areas of enclosed buildings. If a sufficient amount is present, it will replace the oxygen and may create a long term asphyxiation hazard if allowed to accumulate. If the percentage increases beyond five percent by volume, it becomes a very dangerous explosive mixture.
Unsafe Levels of Methane
Methane gas that has not been odorized can be very difficult to detect without proper combustible gas detection equipment. According to biotechnology scientists, methane gas has not been shown to be toxic but can cause an explosion (the Lower Explosive Limit) when one volume of methane is mixed with 20 volumes of air (~5% by volume). With that in mind, a gas detection system can be configured to measure the LEL value in real time. Typically, gas detection systems are programmed to generate a warning if the measured value reaches 20% LEL and an alarm if the measured value reaches 40% LEL.
Catalytic Bead vs. Infrared Sensor
If you regularly work with methane, a byproduct or component, it’s important to understand the two types of sensor technologies used to detect methane gas.
- Catalytic Bead Sensors – Preceding the use of infrared sensors, catalytic bead sensors usually cost less and have the ability to detect other combustible solvent vapors in the environment. Working as a Wheatstone bridge circuit, the active filament wound in a catalytic bead sensor uses a platinum wire with a palladium-based catalyst. Unsafe levels of methane are detected when the resistance ratio between the active and reference bead changes.
- Infrared Sensors – Due to the risk of catalytic bead poisoning in environments involving silicone, lead, sulfur, or halogenated compounds, infrared sensors were introduced as an alternative. Using two wavelengths of infrared energy, infrared technology compares the outputs of the gas absorption beam and reference beam to determine if gas is present. Because infrared sensors don’t require oxygen to operate, they can be reliably used around a number of applications without issue. Furthermore, typical infrared sensors include a microprocessor that continuously checks the sensor for proper operation.
Pro Tip: Methane gas is often combined with an odorant that smells like rotten eggs to help you detect leaks. If you smell a peculiar odor, be sure to survey your equipment or call for assistance.
Both catalytic bead and infrared sensors can be configured to detect methane gas, and both have certain advantages. GDS Corp offers gas detectors that utilize both technologies to give you accurate information no matter what environment you’re in.
Connect with our sales team to customize a methane detection system for your particular