At Edinburgh Sensors we value our customers, which is why we prioritise the clarity of the information we provide. We have therefore created an A-Z Glossary of Gas Sensing terminology to ensure that nothing stands in your way of finding the perfect gas sensor to meet your needs. The definitions include the clarification of key gases, key industries and key products.

Please feel free to browse the key terms and their definitions to discover more about the world of gas sensing…

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Boxed Gascard®Edinburgh Sensors’ Boxed Gascard® provides users with access to the Gascard NG range of CO2 detection products in a convenient and robust desktop unit.
Requiring only a suitable power supply and sample gas, the Boxed Gascard® provides fast and reliable CO2 concentration data over a wide range of barometric pressures and environmental temperatures. It brings the accuracy and reliability of the Gascard NG gas sensors to the convenience of a desktop instrument. The Boxed Gascard® is suitable for CO2 monitoring in a diverse range of applications from anaerobic digestion monitoring to plant physiology, where the carbon dioxide concentration in air-like atmospheres needs to be measured from ppm to tens of percent concentration.
View the product page: Boxed Gascard®
Carbon Dioxide (CO2)Carbon Dioxide (CO2) is a chemical compound that is an odourless and colourless gas at room temperature. The compound consists of one carbon atom and two oxygen atoms. CO2 enters the atmosphere through a number of ways; it is released by the exhaling of organisms and it is given off through the combustion of matter. Plants also take in CO2 through the process of photosynthesis.
The presence of CO2 can be detected and measured using an Edinburgh Sensors’ carbon dioxide sensor. Some common applications for a CO2 detector are in monitoring indoor air quality, landfill, process control and controlled environment horticulture.
Despite the fact that Carbon Dioxide is difficult to detect, Edinburgh Sensors’ range of CO2 detectors allow the gas to be strongly absorbed as a result of non-dispersive infrared technology.
Click here to discover more about CO2 detection.
Carbon Monoxide (CO)Carbon monoxide (CO) is a chemical compound which consists of one carbon atom and one oxygen atom. It is a colourless, odourless and flammable gas at room temperature. CO is produced during the incomplete burning of inorganic matter and when it is encountered in concentrations of over 35 ppm it is toxic to humans and animals that use haemoglobin as an oxygen carrier. This is because the CO combines with haemoglobin to form carboxyhaemoglobin, which prevents the blood from carrying oxygen.
Therefore, a Carbon Monoxide monitor is essential because it detects the presence of CO in the atmosphere which cannot be detected by vision or smell. This could prevent carbon monoxide poisoning and save lives.
Find out more: Carbon Monoxide Detection
Carbon TetrafluorideCarbon Tertrafluoride or Tetrafluoromethane is a potent greenhouse gas that has an atmospheric lifetime of 50,000 years. It is used as a low temperature refrigerant and also as a plasma etchant in electronics fabrication. The main industrial emissions of CF4 are as a by-product of smelting aluminium. As a fluorinated hydrocarbon, it absorbs strongly in the infrared and can be detected with NDIR sensors.
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Chillcard NGThe OEM Chillcard NG range of infrared gas sensors from Edinburgh Sensors is designed for the measurement of refrigerant gases such as R125 and R134a and provides a long-term stable solution to the measurement of these and other refrigerant gases.
The Chillcard NG range now includes two new gases, CO (carbon monoxide) and CO2 (carbon dioxide). The equivalent Gascard NG sensors for these gases are designed for use in air-like atmospheres and have reduced source lifetimes when exposed to high levels of hydrogen in the sample stream. The Chillcard NG is set up for single use gas measurement at a time.
Find out more: the Chillcard NG
Gascard NGThe Gascard NG infrared gas sensor is designed for ease of integration with a wide range of gas detection systems that require high quality, accurate and reliable measurement of CO, CO2, CH4 gas concentrations. The Gascard NG is set up for single use gas measurement at a time.
It includes real-time temperature and atmospheric pressure correction via on-board sensors and has the flexibility to incorporate additional gas detection technologies. It has onboard true RS232 communications along with the option of TCP/IP communications protocol.
Follow this link to discover our Gascard NG.
GasCheckThe GasCheck is a series of low cost CO2 sensors that offer high accuracy, good long term stability, negligible cross sensitivity, small size and low power requirement.
The basic GasCheck is available in three ranges 3000ppm, 3% and 10% with a 0 to 1 V non-linear output. A linearization board can be added as an option to give linear 4 to 20 mA output.
The option of a diffusion assembly is available for the 3000ppm unit.
View the product: GasCheck
Gas stunningGas stunning involves using an environment with a high carbon dioxide concentration to cause an animal to lose consciousness. It is a favoured approach in pig and poultry processing throughout Europe, as it reduces risk of injury because there is no need to restrain the animals beforehand, which can also improve the quality of the meat, and is considered one of the most humane stunning methods.
For gas stunning to cause minimal harm to the welfare of the animal, it is crucial to use the correct CO2 concentrations, which can be controlled using a reliable and accurate Edinburgh Sensor’s gas sensor.
Discover more: Monitoring CO2 for Pig and Poultry Processing
Greenhouse Gases (GHG)A greenhouse gas (GHG) is a gas that absorbs and emits radiant energy within the thermal infrared range. The primary greenhouse gases in Earth's atmosphere are carbon dioxide, methane, nitrous oxide, water vapour and ozone. The emission of these gases cause the greenhouse effect, which is the warming of the planet’s surface due to radiation from its atmosphere, which has led to global warming.
Monitoring and accurately measuring these gas concentrations is one way to play your part in combatting the effects of these greenhouse gases.
Read more: Greenhouse Gases
Guardian NG DCThe Guardian NG DC infrared gas monitor, supplied by Edinburgh Sensors, offers near-analyser quality continuous sampling, measurement and display of CO2 concentrations between 0 – 3000ppm by volume from low voltage DC supplies in the range of 18-30V. It can also be used for CH4, CO measurement. The equipment is set up to measure single use gases at a time.
Discover more: Guardian NG DC
Guardian NG gas monitorThe Guardian NG range infrared gas monitor supplied by Edinburgh Sensors offer near-analyser quality, continuous sampling, measurement and display of target gas concentrations. The ‘Guardian NG’ gas monitor range provides high accuracy detection and measurement of either CO2 or CH4 gases, where detection level ranges of between 0 – 3000ppm and 0 – 100% by volume are required. The equipment is used for single gas measurement at a time.
View the page: Guardian NG Gas Monitors
HVACHeating, ventilation and air conditioning (HVAC) is the technology of indoor and vehicular environmental comfort which aims to provide optimal wellbeing, safety and cost efficiency of those inhaling the air. This can be achieved through the use of an air quality sensor which enables us to analyse the quantity of different gases present in the air.
Find out more: Indoor Air Quality Testing for HVAC
Hydrocarbon A hydrocarbon is an organic compound made of nothing more than carbon and hydrogen atoms. Aromatic hydrocarbons (arenes), alkanes, cycloalkanes and alkyne-based compounds are different types of hydrocarbons. Most of the hydrocarbons found on Earth naturally occur in crude oil, where decomposed organic matter provides an abundance of carbon and hydrogen. Edinburgh Sensors’ gas monitors are used to detect valve leaks on bottle filling plant production line.
View our products: Hydrocarbons
Infrared (IR) Infrared (IR) gas detection is a very popular technique in gas sensing technology since many gases have characteristic vibration/rotation absorption spectra with narrow, non-overlapping bands in the infrared spectrum between 2 μm and 20 μm.
Commercial IR gas sensors generally consist of an infrared source, a detector, a gas cell/path, a wavelength selection device and some optical components (lenses or more usually mirrors) to couple the radiation from the source through the gas cell to the detector. The sample gas passes through the gas cell and the detector measures the radiation at the absorption band wavelength of the target gas. When no target gas is present there is no absorbance so the signal reaching the detector is at a maximum. When the target gas is present in the path, the detected signal reduces as the target gas concentration increases.
Discover more: Infrared
IRgaskiT®The IRgaskiT® infrared gas sensor is designed for integration into a wide range of systems where fast, accurate and reliable measurement of carbon dioxide concentrations is required. The electronics module supports a range of available sensors connected via extendable cables, providing the extra flexibility required of a modern OEM instrument.
The IRgaskiT® provides a temperature compensated bench with single button calibration and optional simultaneous voltage and current outputs. The sensor heads are based on a patented technique that provides true, dual wavelength infrared sensing with no moving parts.
Find out more: IRgaskiT
Landfill gasLandfill gas (LFG) is a complex mix of 40-60% methane and the remainder mostly carbon dioxide. Legislation requires that these gases are safely removed to avoid a physical explosion due to the build-up of pressure beneath the cap. Safe disposal usually entails burning such as flare stacks, internal combustion engines or by processing to produce Methane gas fuel.
LFG can be captured, converted and used as a renewable energy resource. Using up LFG helps to reduce odours and prevents methane from migrating into the atmosphere and contributing to local smog and global climate change.
These safe disposal processes require either the measurement of the Methane or the Carbon Dioxide content. Edinburgh Sensors provide gas sensors for both CH4 and CO2 that can be integrated into landfill gas processing systems enabling the monitoring of these gases.
Learn more: Landfill Gas
Methane (CH4)Methane (CH4) is the simplest member of the paraffin series of hydrocarbons and is among the most potent of the greenhouse gases. It is the main constituent of natural gas and its abundance on Earth makes it an attractive fuel, although capturing and storing it poses challenges due to its gaseous state under normal conditions for temperature and pressure.
Non-dispersive infrared (NDIR) is an effective method for measuring methane since it does not rely on the presence of oxygen. The sensor cannot easily be poisoned and it is also fail safe since any malfunction gives a high gas reading.
View our products: Methane
Modified Atmosphere Packaging (MAP)Modified Atmosphere packaging (MAP) is the practice of modifying the composition of the internal atmosphere of a package in order to improve a food product’s shelf life. MAP can extend the visual, textual and nutritional appeal of fresh and minimally processed packaged food through the precise control of the gaseous environment within the packaging. The optimal blend of gases can be found through the monitoring of CO2 concentrations using one of Edinburgh Sensor’s products.
Learn more: Modified Atmosphere Packaging
Nitrous OxideNitrous oxide (N2O) Nitrous oxide, commonly known as laughing gas or nitrous, is a chemical compound that is an oxide of nitrogen. It is a colourless non-flammable gas at room temperature, with a slight metallic scent and taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen.
N2O is used as an anaesthetic gas in dentistry and labour wards and its concentration can be measured using its infrared absorption. This enables the atmosphere in the treatment room to be monitored in order to protect medical staff from the effects of the gas.
View our sensors: Nitrous Oxide
Non-Dispersive Infrared (NDIR) A nondispersive infrared (NDIR) sensor is a simple spectroscopic sensor where the infrared energy is allowed to pass through the atmospheric sampling chamber without deformation. This can be done through the use of an optical filter which allows only transmission of the required wavelength. The main components of an NDIR sensor are an infrared source, a sample chamber or light tube, a light filter and an infrared detector.
It has been shown that optical filters are typically 1000 times more efficient than gratings and up to 100,000 times more efficient than prisms at separating IR wavelengths, so NDIR gas sensors offer real performance advantages over dispersive systems and are the systems of choice.
Find out more: Non-Dispersive Infrared
Original Equipment Manufacturer (OEM)At Edinburgh Sensors, we refer to many of our products as OEM Gas Sensors. OEM stands for Original Equipment Manufacturer, which refers to the fact that we sell our products to organisations that make devices from component parts bought from other organisations. OEM sensors by Edinburgh Sensors are manufactured to the highest specification for integration into a wide range of systems and therefore our parts and equipment may be marketed by another manufacturer.
View our range: OEM Sensors
RefrigerantsA refrigerant is a compound typically found in either a fluid or gaseous state. It readily absorbs heat from the environment and can provide refrigeration or air conditioning when combined with other components such as compressors and evaporators.
Refrigerants such as ammonia, carbon dioxide and non-halogenated hydrocarbons are used within many industries because they do not deplete the ozone layer and have low global warming potential.
View our suitable products: Refrigerants
Sulphur HexafluorideSick building syndrome (SBS) is a medical condition where people who work or live in the same building suffer from symptoms of illness and feel unwell for no apparent reason. It is clear that good building ventilation improves symptoms and that high carbon dioxide levels have a role to play. Therefore, monitoring carbon dioxide levels is an important part of preventing SBS and requires continual, online gas analysis with highly sensitive detectors as sub-1000 ppm concentrations of carbon dioxide have been reported in a major case of SBS.
Find out how we can help: Detection of Sick Building Syndrome
Total Organic Carbon (TOC) AnalysisTotal Organic Carbon (TOC) Analysis is an analytical technique used to determine water quality. It involves the measurement of TOC, which is the amount of carbon that is found in an organic compound. It has become an important indication of approximate levels of organic contamination which can indicate filtration, storage or system failure.
A TOC analyser works by oxidising the organic compound to a form which can be quantified. Oxidising organic carbon produces Carbon Dioxide, which can then be measured using an Edinburgh Sensor’s gas sensor and the value can then be converted into a TOC measurement.
Read more: Total Organic Carbon Analysis


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