Gas in potentially explosive atmospheres – SG350ex and SG5100ex

The GSA measuring devices SG350ex and SG5100ex have been specially developed and certified for use with gas in potentially explosive atmospheres with the suffix “ex” .

When it comes to measuring occupational safety in such a hazardous environment, it makes sense to use the GSA SG350ex or SG5100ex measuring device if contact with flammable gases is possible.

Both GSA measuring devices are equipped for both personal and stationary use for measuring hazardous substances such as gas at the workplace.

What are “gases” and what influence can they have on occupational safety?

Definition of gas

Something is described as a “gas” if the substance is in a gaseous state of aggregation under normal conditions, i.e. 1 bar pressure and 20° Celsius. This means that the molecules can spread and move freely in space.

The basis of thermodynamics is the concept of ideal gases. Under normal conditions (temperature 0°C, pressure 1.013bar), an ideal gas occupies a space of 22.4 liters per mole. This is known as the molar volume and is part of Avogadro’s law.
The general gas equation can be formulated on this basis:

p * V = R * n * T

p: Pressure in Pascal (Pa)
V: Volume in cubic meters (m³)
R: General gas constant 8.32 J/(mol*K)
n: Amount of substance in mol (moles)
T: Absolute temperature in Kelvin (K)

Using the general gas equation, the gas laws (e.g. Gay-Lussac) can be derived and transferred to real gases. For example, the required volume of a gas for a reaction (work process) can be calculated.

Danger from gases during work

At the workplace, contact with gases can have various causes. It can be part of the work process or production or arise as a by-product or waste product.

In both of these cases, the presence of gases is known and requires safety-relevant handling. If pressurized gas cylinders are in use, they may only be used by designated personnel. Proper storage (no direct sunlight, secured against falling over) must also be ensured.

When using, always open the valve slowly and by hand (no pliers or similar). After the gas has been removed, the gas containers must be closed again. DIN EN 1089-3 specifies the color coding of gas containers so that the contents can be identified at first glance.

Examples:

  • White cap: Oxygen (technical); O2
  • gray cap: carbon dioxide;CO2
  • Brown cap: Helium; H

If the gases are used for technical purposes, the pressure containers are gray; if they are used for medical purposes (e.g. nitrous oxide as an anesthetic), the containers are white.

Health hazards due to different gases

The health risk posed by a gas is substance-specific. To provide an insight into this topic, four subcategories of gases that are frequently encountered in everyday working life are listed.

As can be seen from the diagram, these are inert gases, oxidizing gases, combustible gases and toxic gases.

Diagram: Hazards due to gases

Inert gases: Dilute the oxygen content in the air we breathe and can lead to death by asphyxiation. Examples: Carbon dioxide (CO2), nitrogen (N2)

Fire-promoting gases: Support and accelerate combustion, examples: Nitrous oxide (N2O), oxygen (O2)

Flammable gases: Are flammable and burn, can cause explosions, on contact with O2 or ignition source

Toxic gases: Are toxic on contact with the organism (and the environment) and can cause death, depending on concentration and exposure


Occupational health and safety measures apply when gases are used

If the use of gases is necessary at the workplace, various safety measures must be observed.

The GHS pictograms on the gas cylinders indicate the hazards. Safety measures must be taken and complied with accordingly. The concepts adapted to the work process can be viewed in the risk assessment.

Sources:
[1]: Source of contribution image: © auremar / 123RF.com
[2]: https://www.chemie.de/lexikon/Gas.html
[3]: https://www.uni-ulm.de/fileadmin/website_uni_ulm/nawi.inst.251/Didactics/thermodynamik/INHALT/IDEAL1.HTM
[4]: https://www.chemie.de/lexikon/Ideales_Gas.html
[5]: Handout “Safety training; basic module: safe handling of gases”, Air Liquid, June 2015, Düsseldorf
[6]: https://www.bgrci.de/fileadmin/BGRCI/Downloads/DL_Praevention/Gase_unter_Druck__Microsite_/SKG/SKG_008_Erstickungsgefahr_durch_Gase.pdf
[7]: https://www.bgrci.de/gase-unter-druck/gase-wissen/umgang-mit-gasen/
[8]: https://www.vbg.de/apl/arbhilf/unterw/73_umd.htm
[9]: https://www.physik.uni-muenchen.de/lehre/vorlesungen/wise_07_08/EP/vorlesung/vorlesung14.pdf
[10]: https://www.zchl.uni-sb.de/ueberuns/laborgase/plakat-farbkennzeichnung-von-gasflaschen