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Gas Detection Premier And Review

For you veterans out there, this is review or old hat. However, there are plenty of new customers that we encounter who might appreciate some documentation on the basic gas-detection terms and abbreviations. Here are the most common of them.

Controller - The part of a gas detector that provides centralized processing of the gas signal. It receives and responds to the electrical signal from the sensor to output an indication, alarm or other function.

Cross Sensitivity - The predictable response of a detector to compounds other than the target gas.

Dew Point - The temperature at which a gas (air) is saturated with a condensable component.

Diffusion - Process by which particles spread from regions of higher concentration to regions of lesser concentration as a result of random molecular movement. Also used to describe the process by which the atmosphere being monitored is transported to the gas-sensing element by natural random molecular movement.

Electrochemical Sensor - A sensor that uses an electrochemical reaction to provide an electrical output proportional to the measured gas concentration.

Explosion - Rapid uncontrolled combustion process which generates a high temperature, a large volume of gas and a pressure or shock wave.

Explosion Proof (XP) - Method of protection in which an explosion in a hazardous location is prevented by containing any combustion within the device,preventing it from spreading into the atmosphere surrounding the enclosure.

Explosive (or “Flammable”) Limits - Though a flammable liquid can support combustion at its flash-point temperature, to sustain it requires the vapor concentration to be between two specific levels, or “flammable limits”, the lower flammable limit and the upper flammable limit. Any gas or vapor concentration that falls between these two limits is in the flammable range.

Lower Explosive (or “Flammable”) Limit (LEL) - Minimum concentration of a vapor (usually expressed as the percentage of material in air) required to sustain a fire.

Upper Explosive (or “Flammable”) Limit (UEL) - Maximum concentration of a vapor (usually expressed as the percentage of material in air) beyond which a fire cannot be sustained, as the amount of oxygen would be insufficient to continue the fire.


The use of a gas monitoring system, along with appropriate action taken if dangerous levels of gases are detected, can help prevent explosions, injuries or exposure to toxic gases.


They can help prevent gas levels from rising further by triggering the shutoff of gas valves, turning on a ventilation fan, shutting down a process by sounding or audible and visual alarms to alert and evacuate personnel. In some situations, gas monitors are used for process control. The portable gas monitors that TSS provides are generally intended for worker and plant safety and are not intended for process control use where high levels of gases or vapors may be present all the time. 

Toxic gases such as H2S or CO can be present in refinery or petrochemical applications, parking garages, and many other situations. In many plants and factories, toxic gases are used in a process or can be generated by a process. Monitoring of these gases can help to alert personnel to potentially dangerous situations. We have Engineered Systems that can monitor areas 24-7. TSS has decades of experience in designing and fabricating custom fixed systems for gas detection and monitoring.

We can provide high-tech solutions to several application types, such as: • Parking Garages • Enclosed Domes and/or Hangars • Waste Water Treatment • Vehicle Test Cells • Research Laboratory • Fuel Laboratory • Food Processing—and more.