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Risk assessment for gases

Handling gases carries many dangers - but with the right knowledge, risks can be effectively minimized. People who work with gases in everyday operations should therefore be made aware of the different sources of danger.

Gases are extremely versatile substances with different properties. While flammable gases pose the risk of explosion, oxidizing gases are not themselves flammable, but promote the combustion of other substances. In addition, there are harmful, hazardous, toxic and corrosive gases, which pose health risks for employees. In addition, gases (all but oxygen themselves) reduce the oxygen content in confined spaces and can endanger persons present by lack of oxygen.

It is important to always assess the hazards of gases on an individual basis. In the following, we will give you an explanation of the approach to a risk assessment of gases.

What regulations apply to activities involving gases?

Gas bottles are commonly used in daily operations in many industries. Handling and storing these cylinders may seem like a mundane task, but if done carelessly, without safety in mind, gas cylinders can leak or explode, causing serious property damage and/or injury.

There are a number of regulations that apply to the safe storage and handling of pressurised gas cylinders. These include requirements for the quality of pressurized gas containers and their testing, rules for risk assessment and protective measures for gases, their storage and transport.

All of these regulations form the framework for the safe handling of gases in the commercial environment.

In our guide we answer some of the most important questions to ensure safe working with gas cylinders and offer best practice tips for carrying out your risk assessment and for safely storing and transporting your gas cylinders.

The following table (in alphabetical order) provides an overview of the most important regulations that affect the area of "activities involving gases" and contain corresponding specifications and protective measures:

Regulations Content
ADR Regulations and quantity limits for the carriage of gas cylinders by vehicles on the road.
Ordinance on Industrial Safety and Health (BetrSichV) Ordinance on safety and health protection in the provision of work equipment
Ordinance on Hazardous Substances (GefStoffV) Protective measures for employees during activities involving hazardous substances
Product Safety Act (ProdSG) Ordinance on making simple pressure vessels available on the market (6th ProdSV)
TRBS 1201 Inspections of work equipment and systems requiring monitoring
TRBS 2141 Determination and evaluation of hazards due to steam and pressure and corresponding protective measures
TRBS 2152 / TRGS 720, 721, 722 Identifying and preventing explosion hazards caused by substances that can form explosive atmospheres
TRBS 3145 / TRGS 745 Transportable pressurised gas containers - Filling, holding, internal transport, emptying
TRBS 3146 / TRGS 746 Regulations for stationary pressure systems for gases
TRBS 3151 / TRGS 751 Avoidance of fire, explosion and pressure hazards at filling stations and filling plants for land vehicles
TRGS 407 Risk assessments for activities involving gases
TRGS 500 Protective measures for handling hazardous substances
TRGS 510 Storage of hazardous substances in portable containers
TRGS 512 Special regulations and protective measures for fumigations
TRGS 513 Special regulations and protective measures for work on sterilisers with ethylene oxide and formaldehyde
TRGS 522 Special regulations and protective measures for room disinfection with formaldehyde
TRGS 525 Handling of hazardous substances in facilities for human medical care
TRGS 526 Special regulations and protective measures for activities in laboratories
TRGS 528 Special regulations and protective measures for welding work
TRGS 529 Activities in the production of biogas
TRGS 725 Measuring, control and regulating equipment in the context of explosion protection measures
TRGS 800 Fire protection measures

Why is a risk assessment for gases needed?

The risk assessment is the central element in occupational health and safety. It is the basis for systematic and successful safety and health management. According to the Occupational Health and Safety Act (ArbSchG) and the accident prevention regulation "Principles of Prevention" (BGR A1 or GUV-V A1), all employers - irrespective of the number of employees - are obliged to carry out a risk assessment. § Section 5 of the Occupational Health and Safety Act (ArbSchG) regulates the employer's duty to identify and assess hazards and specifies possible causes of hazards and subjects of the risk assessment. § Section 6 obliges employers to document the result of the risk assessment, the occupational safety and health measures they have defined and the result of their review.

Who carries out the risk assessment for gases?

The risk assessment must be carried out by a competent person. This person has sufficient knowledge of the hazardous properties of the hazardous substances used and is familiar with the work processes and the activities to be carried out. He knows the regulations, can assess the working conditions and evaluate the specified protective measures during an activity. In company practice, this task is usually performed by safety, waste, hazardous goods and fire protection officers. However, with regard to the storage and handling of gases, many of these responsible persons find it difficult to assess the situation correctly.

Important definitions of terms according to TRGS 407

TRGS 407 contains numerous special specifications for carrying out a risk assessment for gases. Basically, TRGS 407 "Risk assessment for gases" is a supplement to TRGS 400 "Risk assessment for activities involving hazardous substances". However, it contains some definitions important for the assessment of gases, such as:

Term Definition
Gases Gases in the sense of TRGS 407 and according to the CLP Regulation as well as dangerous goods legislation are substances or mixtures/preparations which have a vapour pressure of 300 kPa (3 bar) at 50 °C or are completely gaseous at 20 °C and a standard pressure of 101.3 kPa. Gases are heavier than air in relation to their state after discharge, i.e. at the respective temperature of the gas and the pressure of the ambient atmosphere, if their density is > 1.3 kg/m3 or equal to air if their density is ≤ 1.3 kg/m3 and ≥ 1.2 kg/m3 or lighter than air if their density is < 1.2 kg/m3. In TRGS 407, the term "gas" is used in the sense of "gas and gas mixture", otherwise it is explicitly referred to, e.g. by using the term "pure gas" or by using the term "gas mixture" alone.
Refrigerated liquefied gases Refrigerated liquefied gases are gases whose liquid state is maintained at a temperature lower than the ambient temperature by cooling, evaporation or thermal insulation.
Gas mixtures Gas mixtures are mixtures which meet the definition of gases in the CLP Regulation and which consist of two or more gases or possibly also liquids. They have a vapour pressure of more than 300 kPa (absolute) at 50 °C or are completely gaseous at 20 °C and a standard pressure of 101.3 kPa. They may also contain one or more condensable substances. Any gas with a critical temperature Tk ≥ - 50 °C and any liquid are considered condensable.
Pressurised gas containers Pressurised gas containers are pressure containers for gases, regardless of pressure. The pressurised gas container includes the equipment parts that can influence its safety. A distinction is made between mobile and stationary pressurised gas containers.
Pressure systems Pressure systems within the meaning of this TRGS are pressure systems in accordance with TRBS 2141, insofar as they are intended for gases.

Risk assessment for gases - what to consider

All gas cylinders contain gases under pressure that may present a risk of explosion if not safely handled and stored. The Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) requires employers to carry out a site specific risk assessment for each gas cylinder store.

The risk assessment must be carried out by a qualified person who has sufficient knowledge of the hazardous properties of the substances being used and is familiar with the work processes involved in order to correctly assess the working conditions and evaluate the protective measures required.

The first step is to identify the hazardous properties of the gases used in your facility. The safety data sheet will provide you with all the necessary information as it will highlight all dangerous properties of the stored substance.

The following must also be considered during the risk assessment:

  • Explosion limits (OEG / LEL can be shifted at elevated temperature / pressure)

  • Temperature (can lead to pressure increase in the compressed gas tank)

  • Chemical properties (eg, instability)

  • Self-igniting (increased risk of fire / explosion)

  • Corrosion (eg, sulfur dioxide, can attack containers)

  • Toxic gases (eg, chlorine)

  • Suffocation

  • Gases heavier than "air" (can collect near the ground)

  • Polymerization

It should be noted that the hazards associated with the handling of gases are so varied that only a few of the effects can be stated here. A detailed analysis of the hazards of the gas must be made on a case-by-case basis.

Once the risks have been analyzed, the handling must then be considered. This includes internal transport and processing and handling by employees. The following situations describe specific hazards as examples:

  • Unintentional release (eg. leaky connections to valves)

  • Mixing gases (eg. when welding with acetylene / oxygen)

  • External effect on the compressed gas container

  • Improper maintenance (eg. pressure regulator on the valve is defective)

  • Deviation from the prescribed purpose


Important: It is not possible to create a "standard risk assessment" for all gases. Each gas must be considered individually and evaluated according to the hazards arising from it. A cause analysis can provide further support here. In addition, when assessing the risk of gases, the technicians, users or operators should be included in the report.

Labeling of Gas Cylinders

Whether as a basis for the risk assessment or immediately before use, it is essential for the user to know exactly what is in a gas bottle.

As required by law, each individual gas cylinder has to have a label which identifies its contents and provides basic safety information on the hazard(s) associated with the product. The labeling of gas cylinders has been regulated by EN 1089 since 1997. Amongst other things, this specifies a uniform colouring (EN 1089-3), which serves as additional information about the properties of the gases contained.

It is the responsibility of the person filling the gas cylinder to affix a label.

Board 1 – General labelling rule for gases and gas mixtures

Board 2 - Special marking for common gases

Board 3 – Special labelling for inhalation mixtures

Board 4 – Special labelling for protective mixtures

Attention: The colour coding according to EN 1089-3 only refers to the cylinder shoulder, not to the jacket colour. The standard does not apply to bundle and trailer cylinders, fire extinguishers and gas cylinders for liquid gas. During the transitional period until the end of 2006, a large "N" (= Neu, New, Nouveau) was additionally printed on the cylinders to avoid confusion with old cylinders.

The bottle colour does not replace the hazardous goods label! This is the only binding identification of the bottle contents.

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The specialist information on this page has been compiled carefully and to the best of our knowledge and belief. Nevertheless, DENIOS Ltd cannot assume any warranty or liability of any kind, whether in contract, tort or otherwise, for the topicality, completeness and correctness either towards the reader or towards third parties. The use of the information and content for your own or third party purposes is therefore at your own risk. In any case, please observe the locally and currently applicable legislation.

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