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Indoor Air Quality and Protective Atmosphere Measurement

Atmospheric control and measurement covers a wide range of products for a wide range of industries. These are available in homes or public businesses (ERP). They range from measuring indoor air quality to controlling the protective atmosphere (MAP) of food packaging.

Indoor air quality analysis

According to the World Health Organization, air pollution causes approximately 50,000 deaths in France every year. Contrary to popular belief, the air inside a home or industrial building can be up to 10 times more polluted than the air outside! Indoor air quality is a real problem and presents significant challenges.

In addition to pollutants brought from outside, many substances can be released into the building. These include building materials (floor and wall coverings, insulation), furniture (adhesives, varnishes), incinerators, animals, and various human activities (smoking, household products, do-it-yourself projects, etc.).

For benzene, formaldehyde to measure indoor air quality colorimetric reagent tubes or devices such as CO2 sensors are available that measure the carbon dioxide released by human exhalation and the risk of transmitting viral infections such as COVID-19. In this field, we can say that Dräger reagent tubes perform best for measuring more than 500 gases and vapors.

Carbon dioxide Measuring its concentration is the simplest way to determine the air quality in a room and evaluate the quality of ventilation. When the CO2 concentration is very high indoors (above 1000 ppm), the air is not considered healthy. In this case, it is necessary to ventilate the room (open windows, fan, etc.).

Monitoring indoor air quality has now become mandatory in some public businesses such as daycares, kindergartens, high schools and recreation centers.

Protective Atmosphere Analysis (PAA)

Protective atmosphere packaging, It involves protecting foodstuffs from contact with air by replacing them with other gases of industrial origin. In practice, this technique is regularly combined with low-temperature preservation. Various gases authorized for modified atmosphere packaging are listed in European Directive 2008/84/EC, the main ones being nitrogen (N2), oxygen (O2), carbon dioxide (CO2) and less commonly argon (Ar).

Nitrogen helps preserve dry produce, while oxygen preserves fresh fruits, vegetables, meat and fish. Argon is used to package delicate products such as wine. For example, the recommended modified atmosphere for apples is 5% oxygen, 5% carbon dioxide and 90% nitrogen. The ideal modified atmosphere for red meat retail sales is 70% oxygen and 30% carbon dioxide.

Gas analysis in modified atmosphere packaging includes the detection and measurement of oxygen and carbon dioxide, with nitrogen (derived by difference) as the balanced gas. Most instruments used to perform these measurements (e.g. the OXYBABY protective atmosphere analyzer) use a pump sampling system to draw a gas sample through a probe inserted into the package.

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Combustion Controllers And Analyzers

Combustion analyzers, It precisely monitors the gas emissions produced by any device running on fossil fuel (gas, oil, gasoline, coal, wood, pellets, etc.). Accurate and easy to use, these devices measure oxygen (O2) or excess air, CO (carbon monoxide), Nox (nitrogen monoxide and dioxide) and SO2 (sulfur dioxide). 

Combustion analysis for optimum efficiency

Fixed or portable combustion analyzers allow optimizing combustion efficiency and limiting emissions. boiler rooms They are popular for commissioning, adjustment, maintenance and certification of thermal installations or . They are becoming increasingly important to face environmental and economic constraints through proper control of energy prices.

A simple system used to control exhaust gases from handling equipment in confined spaces (e.g. gas-powered forklifts). from the carbon monoxide analyzer, NOx ( nitric oxide And nitrogen dioxide ), sulfur dioxide (SO2) and oxygen You will find high-performance professional equipment in this category, right up to more advanced models that also analyze the content (O2).

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Explosive Measurement Devices, Flammable Gas Detectors, LEL Measurement

Explosive gas detectors , natural gas, LPG (butane, propane), pentane, hydrogen, hydrocarbons, alcohols, solvents, ammonia, etc. They are flammable gas detectors for leak detection of explosive gases such as They detect flammable gases and measure their amounts in the atmosphere according to the Lower Explosive Limit (LEL). Explosive There are two sensor technologies for gas detection: catalytic sensors (most commonly used) and infrared sensors for harsh environmental conditions.

Explosive gas detectors with catalytic cells

Catalytic diffusion cells are the most commonly used for 4-gas detectors and flammable vapor detection. Through the measuring principle, there is a relationship between the presence of flammable gases and temperature. This temperature increase was then converted into a measurable quantity: LEL (lower explosive limit). Although this measuring technology has an excellent price/performance ratio, it has some disadvantages:

  • It can only operate with a minimum oxygen content of more than 10% (completely ineffective in an inert environment).
  • It does not distinguish between explosive gases present (same principle as a scale: it gives the weight but does not tell who is on the scale).
  • Premature wear if explosive gases are detected frequently or continuously (even with low LEL values).
  • Those with high sensitivity to poisons such as silicon, lead or sulfur compounds.

Combustible gas detectors with infrared cells

Infrared absorption cells are mainly used for the detection of some explosive gases (when the IR curve is available). It is a more expensive technology than catalytic diffusion technology, but it has many real technical advantages:

  • Very long life.
  • They are not constantly exposed to flammable gas or cell saturation (measurement above 100% of LEL).
  • Immunity to poisons such as silicates or H2S.
  • Possibility to work in inert atmospheres (without oxygen).
  • The measurement is virtually error-free because the detector systematically alarms if there is a malfunction

IR sensors, on the other hand, do not work with monochromatic cells such as hydrogen.

ATEX Explosion Meter

ATEX approval (for ATmosphère EXplosive ) indicates the capability of the equipment to integrate the high explosive risk zone by not supporting explosion triggering (flame, spark, etc.). Approved for use in an explosive atmosphere ATEX explocimeter (or ATEX detector for explosives) guarantees maximum safety for all teams working in a hazardous area.

It is a portable version of personal protective equipment used in many activity sectors such as oil and gas industries, heavy chemicals, metallurgy, water treatment and sanitation. This PPE is also used to ensure safety when entering confined spaces (as part of the CATEC system) and in public works. It is also an integral part of firefighter equipment.

In parallel, it is implemented in a fixed version connected to a gas detection controller or a safety automation . The flammable gas transmitter allows to ensure the safety of all facilities exposed to such risks.

LEL of the most common flammable gases

The lower explosion limit is expressed as a percentage of the total volume (%/volume).

Acetone: 2.5% – Acetylene: 2.5% – Ammonia: 15.0% – Benzene: 1.2% – Butane: 1.9% – Ethanol: 3.3% – Hydrogen: 4.0% – Carbon monoxide: 12.5% ​​– Methane CH4: 5.0% – Methanol: 6.0% – Pentane: 1.4% – Propane: 2.1% – Styrene: 0.9% – Toluene: 1.1% – Xylene: 1.1%.

For benzene, styrene, toluene and xylene, see also the detection of volatile organic compounds page .

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Refrigerant Detectors (Freons, Refrigerants)

Whether refrigerants used in cold storage or air conditioning systems, freon gases are imperceptible to humans (colourless, odorless) and therefore a freon detection The use of the system is essential. refrigerant gas detectors Its use faces several challenges in the refrigeration sector: safety of goods and people, costs associated with refrigerant leaks and environmental impact (subject to regulation).

Freon detection (refrigerant detectors)

Halogenated hydrocarbons belonging to the CFC and HCFC families have their own regulation: gas detection device Prohibiting or limiting its use with the obligation to install (refrigerant gas detectors). Refrigerants from other families are subject to regulations regarding chemical products, but common sense would also include monitoring for leaks.

Freons are generally heavier gases than air. They tend to stagnate in the ground and displace oxygen. Best detection of refrigerant leaks For , refrigerant gas detectors will be placed under the refrigeration unit and connected to a gas detection unit. In the event of a leak, the central gas detection unit will neutralize the cooling system by cutting off the power supply.

Freon classifications and categories

Freons are divided into several main categories based on their properties. Depending on the specificity of the needs, certain categories should be preferred:

  • Organic compounds: water, CO2 (carbon dioxide), NH3 (ammonia)
  • Hydrocarbons: butane, pentane, propane, propylene, etc.
  • CFCs (chlorofluorocarbons): R11, R12, R113, R115, R502
  • HCFCs (hydrochlorofluorocarbons): R21, R22, R123, R124, R401a, R402a, R408a, R409a
  • HFCs (hydrofluorocarbons): R32, R125, R134a, R15a, R143a, R152a, R404a, R407a, R410a, R507
  • Unclassifiable refrigerants: R630, R631, R12b1, R12b1, etc.

Refrigerants are rarely referred to by their international names because the pronunciation of their names is complicated. An abbreviation of the form R-ABCDe is preferred, R stands for refrigerant.

  • A: The number of double bonds is invisible if equal to 0
  • B: number of carbon atoms minus one (C-1), invisible if equal to 0
  • C : number of hydrogen atoms plus one (H+1)
  • D : number of fluorine atoms (F)
  • E: letter used to identify isomers (similar gross formula but not in semi-developed form)

For example, R134 is a freon consisting of 2 carbon atoms, 2 hydrogen atoms and 4 fluorine atoms.

Properties of refrigerants

With the exception of some organic compounds or hydrocarbons, refrigerants are generally not harmful to humans: they are non-flammable, non-corrosive and non-toxic. However, in case of abundant leakage, they replace breathable air, especially in poorly ventilated environments (hotel rooms, EHPAD, nurseries, schools, dormitories, etc.).

In addition to the risk of anoxia, some freons also have anesthetic properties, making them potentially dangerous; hence the need (and common sense) to install a leak detection system.

Practical guide to detecting refrigerants

The GTC Industrial team offers you a practical guide to detecting refrigerants. In this technical document you can find all the information and equipment available for the control of refrigerants in all your cooling applications:

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VOC Detection – Volatile Organic Compounds Detectors

Detecting VOCs (volatile organic compounds) is complicated because they tend to evaporate very easily at room temperature. They form a large family of gases and gaseous substances, many of which are considered pollutants, toxic or carcinogenic. Their volatile nature allows them to spread rapidly in the atmosphere, hence the need to detect and measure them to better protect ourselves. A variety of VOC detection techniques are available, from simple passive rosette to PID lamp and chromatography.

Detection of volatile organic compounds (VOC)

Their properties and health effects vary depending on their nature. They can range from simple olfactory disturbance to mutagenic disorders, various irritations and decreased respiratory capacity. VOCs Determination of toxicity (rather than explosiveness) in (fixed or portable) is much wiser to analyze the gas concentrations present.

In fact, the detection of VOCs There is a real illogicality about . Indeed, even if they are capable of forming explosive compositions, current concentrations must reach tens of thousands of parts per million (ppm). The main risk of volatile organic compounds is their toxicity at low concentrations on the order of a few tens of ppm.

5 VOC groups

Alkanes

Alkanes (or hydrocarbons) come mainly from petroleum products and contain only carbon and hydrogen atoms, such as: butane , ethane, heptane, hexane, octane, pentane or propane . In general, alkanes are not very reactive and play less of a role in ozone formation than other VOCs. 

Alkenes and alkynes

Alkenes and alkynes, acetylene, ethylene are unsaturated hydrocarbons characterized by at least one double bond (alkenes) or triple bond (alkynes) between two carbon atoms, such as isoprene or propylene. These are mainly used in the chemical industry and are produced during oil refining. Alkenes are more reactive than alkanes due to the presence of a double bond, alkynes are even more reactive (triple bond).

Aldehydes and ketones

Aldehydes and ketones are unsaturated organic compounds (also called carbonyl compounds) obtained as a result of incomplete combustion of fuels or wood, or chemical derivatives of an alcohol formed by the loss of two hydrogen atoms (ketones), e.g. acetone, acrolein, formaldehyde or MEK.

Monocyclic aromatic hydrocarbons

Monocyclic aromatic hydrocarbons, benzene, cymene, naphthalene, styrene , toluene or hydrocarbons containing a benzene nucleus, such as xylene.

Halogenated hydrocarbons

Halogenated hydrocarbons include chlorinated, brominated, or fluorinated hydrocarbons. These VOCs are present in the air due to their use as solvents, refrigerants, insecticides, or aerosol propellants such as chlorobenzene, chloroform, vinyl chloride, freons R11, R12, R22, R114, or trichloroethylene. These compounds are quite stable and can persist in the atmosphere for long periods of time.

Sectors of activity exposed to VOCs

Due to the impressive number of substances grouped under this name and their highly volatile nature, volatile organic compounds (non-exhaustive list) are present in a large number of industrial sectors such as: 

  • Cosmetics industry: deodorants, disinfectants, nail polish or nail hardeners 
  • Medical, paramedical and veterinary sector: alcohol, bactericides, insecticides
  • Food industry: disinfectants
  • Paper industry: Orange packaging, computer paper 
  • Industry and use of dyes and printing inks (preservatives) 
  • Industry and use of dyes and printing inks (preservatives) 
  • Textile industry: de-icing, bleaching of colored textiles
  • Leather and fur industry: preservation and tanning of leather, preservative 
  • Disinfection of premises: household detergents
  • Horticulture and agriculture: Bactericides, fungicides and herbicides 
  • Photography: stabilizers and stabilizers 
  • Exhaust gases from diesel engines
  • Fumes from burning wood, coal and polyethylene
  • Gasoline and oil refining