A-Z Sensor Terminology Guide

A-Z Sensor Terminology

Your GasLab Sensor Industry Terminology, Defined.

GasLab.com has been recognized as one of the leaders in gas detection, specifically for Oxygen measurement. We now offer a detailed range of sensor solution and industry terms from A-Z, from Accuracy all the way to Zirconia.


The degree of correctness with which the measuring system yields the "true value" of a measured quantity, where the "true value" refers to an accepted standard. Typically described in terms of maximum percentage of deviation expected based on a full-scale reading.

Ambient air

Air to which the sensing element is normally exposed.

Ambient pressure

the pressure of the surrounding medium, such as a gas or liquid, in contact with the object.

Biomedical research

Encompasses a wide array of research, extending from "basic research" (also called bench science or bench research),– involving fundamental scientific principles that may apply to a preclinical understanding – to clinical research, which involves studies of people who may be subjects in clinical trials. Within this spectrum is applied research, or translational research, conducted to expand knowledge in the field of medicine.

Biomedical Research

Calibration gas

The known concentration(s) of gas used to set the instrument span or alarm level. 

Carbon Dioxide

Is a colorless gas with a density about 60% higher than that of dry air. Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms. It occurs naturally in Earth's atmosphere as a trace gas. The current concentration is about 0.04% (410 ppm) by volume, having risen from pre-industrial levels of 280 ppm. Natural sources include volcanoes, hot springs and geysers, and it is freed from carbonate rocks by dissolution in water and acids. Because carbon dioxide is soluble in water, it occurs naturally in groundwater, rivers and lakes, ice caps, glaciers and seawater. It is present in deposits of petroleum and natural gas. Carbon dioxide is odorless at normally encountered concentrations. However, at high concentrations, it has a sharp and acidic odor.

Carbon Dioxide Molecule

Carbon Monoxide

An odorless, colorless, and tasteless flammable gas that is slightly less dense than air. It is toxic to animals that use hemoglobin as an oxygen carrier when encountered in concentrations above about 35ppm.


The rapid oxidation of a material evolving heat and generally light.

Confined Space

A space with limited entry and egress and not suitable for human inhabitants. An example is the interior of a storage tank, occasionally, entered by maintenance workers but not intended for human occupancy. Hazards include harmful dust or gases, asphyxiation, submersion in liquids or free-flowing granular solids (grain bins) electrocution or entrapment. 

Cross sensitivity

Many O2 sensors have cross-sensitivity. This means that environments can pollute the sensors. For example- vapor from combustible gases, vapors from heavy metals, Sulphur compounds, etc.


The production and behavior or materials at very low temperatures. It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume a gas to be cryogenic if it can be liquefied at or below −150 °C (123 K; −238 °F). The U.S. National Institute of Standards and Technology has chosen to consider the field of cryogenics as that involving temperatures below −180 °C (93 K; −292 °F).



A way of measuring which relies on an electrolyte which is consumed over a short period of time. Typical feedback on the lifetime from an electrochemical sensor is on average 2 years.


A housing style that is sealed on the base which allows for a clean gas sample stream into the sensor which can be completely removed from the process environment. Allows for a better sample gas management and options in terms of how the sensor can be situated.


Mainly used in the production of industrial resins e.g. for particle board and coatings. In view of its widespread use, toxicity, and volatility, formaldehyde poses a significant danger to human health. In 2011, the US National Toxicology Program described formaldehyde as "known to be a human carcinogen." 


Gas analysis probe 

Designed for monitoring of oxygen content within flue or stack gases, the GAP has relays, analog and modbus outputs along with pressure and temperature compensation making it a complete analyzer for combustion optimization and burner/boiler applications.


A phase of matter which expands indefinitely to fill a containment vessel. Characterized by a low density.


Heating, Ventilation, and Air Conditioning (HVAC) are used worldwide to monitor and regulate the environmental conditions in every type of property and practically all vehicles on the road.

HVAC Example

Hydrogen Sulfide 

It is a colorless chalcogen gas with the characteristic foul odor of rotten eggs. It is very poisonous, corrosive, and flammable. According to OSHA, A level of H2S gas at or above 100 ppm is Immediately Dangerous to Life and Health (IDLH). Entry into IDLH atmospheres can only be made using: 1) a full facepiece pressure demand self-contained breathing apparatus (SCBA) with a minimum service life of thirty minutes, or 2) a combination full facepiece pressure demand supplied-air respirator with an auxiliary self-contained air supply.

Incubator (culture) 

A device used to grow and maintain microbiological cultures or cell cultures. The incubator maintains optimal temperature, humidity and other conditions such as the CO (CO2) and oxygen content of the atmosphere inside. Incubators are essential for a lot of experimental work in cell biology, microbiology and molecular biology and are used to culture both bacterial as well as eukaryotic cells.


A segment of the economy involving the manufacturing and transportation of products. Sensors are used in a variety of industries and applications (boiler combustion, robotic process, automation.)

Industrial Example


A facility that provides controlled conditions in which scientific to technological research, experiments and measurements may be preformed.


The time delay required for a system to completely respond to a change in the input signal.


A chemical compound. It is a group-14 hydride and the simplest alkane, and is the main constituent of natural gas. The relative abundance of methane on Earth makes it an attractive fuel, although capturing and storing it poses a challenge due to its gaseous state under normal conditions for temperature and pressure. A major greenhouse gas. Because methane is lighter than air, it tends to rise and accumulate near the higher stagnant parts of enclosed buildings and tightly closed manure storage pits. It is most likely to accumulate during hot, humid, weather. 

Methane Molecule


Sensors having dimensions in the range or 10-7 to 10-3 meters, as is typical of solid-state sensors employing silicon microtechnology. 

Modified Atmospheric Packaging 

A technology used to preserve the quality of fresh produce and meat so that it can be sold to markets far away from where it is grown, extend the marketing period, and to help suppliers reduce food waste within the cold chain. 

Modified Atmospheric Packaging

Operating Temperature Range

The Range of temperatures over which a sensor can be used with a specified maximum error.

Optochemical Oxygen Sensor

The measuring principle of an optochemical oxygen sensor is based on the effect of dynamic luminescence quenching by molecular oxygen. This kind of oxygen sensor is frequently used in the pharmaceutical industry, medical research industry, and in the beverage industry. State-of-the-art optochemical oxygen sensors are basically maintenance-free compared to an electrochemical optode (also known as a Clark electrode). Furthermore, the response time is faster and the measurement doesn’t consume oxygen (it is a non-consumptive measurement).


Oxygen is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas. Diatomic oxygen gas constitutes 20.8% of the Earth's atmosphere.

Oxygen Molecule


Refers to a self-contained, battery-operated or transportable gas monitor worn or carried by the person using it. A gas detector that can be carried.

Parts Per Million (PPM)

Parts per million is the ratio of one gas to another. Example: 100ppm of O2 is equivalent of 100 Oxygen molecules in a count of a million gas molecules, the remaining 999,000 molecules would be made up of other gases. 1ppm is roughly equivalent to 5 liters of material in and Olympic-size swimming pool.


The difference between the minimum and maximum values of sensor output in the intended operating range. 

Response Time 

The time it takes for the sensor’s output to reach its final value. A measure of how quickly the sensor will respond to changes in the environment.

Sample Draw 

Refers to a method to cause deliberate flow of the atmosphere being monitored to a gas-sensing element. 


The amount of of change in a sensor's output in response to a change at a sensor's input over the sensor's entire range. Provides an indication of a sensor's ability to detect changes. 


Is a device, module, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics, frequently a computer processor. A sensor is always used with other electronics. 2) A gas detecting sensor converts the presence of a gas or vapor into an electrically measurable signal. The sensor is the heart of a gas monitor. 

Sensor Examples

Smart Sensor 

A sensor in which the electronics that process the output from the sensor, and forms the modifier, are partially or fully integrated on a single chip. 


A physical quantity expressing hot and cold. It is measured with a thermometer calibrated in one or more temperature scales. The most commonly used scales are the Celsius scale (formerly called centigrade), Fahrenheit scale, and Kelvin scale. 

Test Probe 

A physical device used to connect electronic equipment to a device under test (DUT). Test probes range from very simple, robust devices to complex probes that are sophisticated, expensive, and fragile. 

Toxic Gas

Any substance which causes illness or death when inhaled or absorbed by the body in relatively small quantities. 

Toxic Gas


The gaseous state of material below its boiling point.

Zero Gas

Clean air, and is an excellent way of insuring that a small release of gas is not near the sensor while zeroing the sensor signal during calibration. 


A type of oxygen sensor. It does not measure oxygen concentration % but measures partial pressure of oxygen in a gas or mixture of gases.

Zirconia Sensor

Older Post Newer Post