Detection of explosive combustible gas
Explosive gases, also known as EXPLO gases or combustible gases, detected by explosimeters collect a large number of gases that can ignite or explode at certain concentrations. Among the most known are natural gas, LPG (butane, propane), pentane, hydrogen, hydrocarbons, alcohols, solvents, ammonia, etc.
The detection of combustible gas is measured from 0 to 100% LEL (Lower Explosive Limit: minimum concentration that can cause the gas to ignite or explode) and the explosimeter generally indicates the concentration in 1% steps. Depending on the substance, the LEL value differs: for example 2.5% for methane, 4% for hydrogen, 3.3% for ethanol or 15% for ammonia.
Combustible gas leak detector measurement technology
An explosimeter or a fixed combustible gas detector mainly uses 2 types of technologies:
The catalytic sensor explosimeter
Catalytic diffusion gas detection sensors are the most widely used devices for the detection of combustible gases and vapors. This excellent value for money measurement technology has three main disadvantages:
- Can only operate with a minimum oxygen concentration greater than 10% (totally ineffective in an inert environment).
- Premature wear in case of frequent or permanent combustible gas detection (even in case of low LEL values).
- High sensitivity to poisons like silicone, lead or sulfur compounds.
The infrared combustible gas detector
The infrared absorption sensors are mainly used for the detection of certain combustible gases (when the IR curve is available). This is a more expensive technology than the catalytic diffusion technology but it has many technical advantages:
- Very long lifetime.
- Immunity against catalytic poisons.
- Operating in inert atmospheres (without oxygen).
The ATEX explosimeter
The ATEX certification indicates the ability of equipment to integrate a so-called ATEX zone (for EXplosive ATmosphere), with a high risk of explosion requiring secure equipment (not promoting incident triggering: flame, spark, etc. ). An ATEX explosimeter (or an ATEX combustible gas detector) approved for use in an explosive atmosphere guarantees maximum safety for all teams working in at-risk areas.
A combustible gas monitor, or LEL detector is a personal protective equipment used in many areas classified as ATEX zones such as certain manufacturing or oil and gas industries. These PPE are also used to secure an operation when entering confined spaces. The explosimeter is also an integral part of the firefighting equipment.
At the same time, in many applications a fixed combustible gas detector is very often deployed in a complete system connected to a gas controller. The ATEX explosive gas transmitter makes it possible to secure entire installations subject to this type of risk. These fixed gas detectors are found, for example, in refineries, factories manufacturing solvents or paints, in distilleries, etc.