Explosions can occur in all operations where flammable liquids, gases and/or dusts are handled. Often, explosions occur unexpectedly.
Explosion protection: The most important in brief
- It is about preventing such events safely and where this is not possible, to limit their effects. This is done by:
- Risk assessment
- Risk evaluation
- Reduction of risk through appropriate measures
- Unwanted explosions pose a danger to people, the environment and technical equipment.
- Explosions generally spread very quickly.
- Whoever handles flammable or explosive substances must deal with explosion protection.
Creation of an explosion
Explosions are characterized by a sudden increase in pressure and temperature. Depending on the speed of propagation, such events are divided into deflagrations and detonations:
- Deflagration: propagate at velocities below the speed of sound (< 1'000 m/s)
- Detonations: propagate (eg. in pipelines) spread with velocities around 2'000 m/s
In general, three factors must interact to obtain an explosion:
- presence of a fuel
- presence of an oxidizer (usually air)
- presence of an effective ignition source
In the case of explosives, both the fuel and the oxidizer are present in chemically bound form, so that ignition without atmospheric oxygen can be triggered by an effective ignition source alone. In a reaction in air, the fuel may be present as a gas or vapor, in the form of droplets, or as a fine solid (dust)
What does explosion protection involve?
The subject area of "explosion protection" aims to ensure compliance with all legal requirements - but above all to prevent events that lead to damage to people, equipment or the environment.
Explosion protection defines:
- Measures to prevent the formation of an explosive atmosphere
- Measures that prevent the ignition of an existing explosive atmosphere
- Measures that limit the effects of an explosion
Why is explosion protection needed?
- Legal requirements: In Switzerland, various standards explicitly or implicitly require dealing with the topic of explosion protection. These are, for example, the Ordinance on Accident Prevention (VUV), the Ordinance on Product Safety (PrSV), the Ordinance on Equipment and Protective Systems for Use in Potentially Explosive Atmospheres (VGSEB), the Low Voltage Installation Ordinance (NIV), the Machinery Ordinance (MaschV) or the Major Accidents Ordinance (StFV).
- More than the purely legal aspects is to weigh the human suffering that an event can entail.
- In addition, there are operating losses, costs for repair or replacement of equipment and bad press.
The protection of people, nature and equipment from explosions is in the elementary interest of every company. If it cannot be safely ruled out that an explosive atmosphere will form, appropriate precautions must be taken.
Risk assessment includes:
- Recognizing explosion hazards
- Risk assessment
- Reducing the risk by defining suitable measures
What does explosion protection consist of?
A distinction is made between primary explosion protection, secondary explosion protection and constructive explosion protection.
Primary explosion protection (prevention of the formation of explosive atmospheres)
- Substitution of the explosive substance
- Dilution or removal of the explosive substances
- Passivation of the explosive Atmosphere
- Isolation (technically tight construction)
Secondary explosion protection (avoidance of effective ignition sources)
Constructive explosion protection (Control of the risk of an explosion by the selection of suitable equipment, z.E.g. pressure shock resistant design, pressure relief, etc.)
How can explosions be avoided?
By safely preventing conditions that could lead to explosions.
- The simplest measure starts with the fuel. Can the fuel be substituted with a non-combustible or low flammability substance?
- Can the concentration of fuel in the atmosphere be safely limited below the lower explosion limit? Here, effective ventilation or superposition with a non-oxidizing gas (e.g. nitrogen), i.e. inerting, can be achieved.
- Can it be ensured that no ignition sources are present? This is done by appropriately designed electrical equipment, avoidance of elevated temperatures, avoidance of electrostatic charging, avoidance of sparking and avoidance of hot surfaces due to friction.
- Further technical measures such as flame arresters, flame monitors and quick-acting devices or extinguishing devices are used as individual solutions.
Who needs to deal with it?
Whoever handles flammable or explosive substances must think about explosion protection. Anyone who is unsure should consult an expert. Explosions are rather rare in Switzerland, but the consequences of an explosion can be devastating.
How does SBIS support?
The specialist staff of SBIS AG has many years of experience in an industrial environment and has in-depth knowledge in the field of explosion protection.
We support you with analyses and advice:
- Do you have to take steps regarding explosion protection?
- What explosion risks exist and how are they to be evaluated?
- Which alternative measures for explosion protection are available and which measure is the optimal one for a concrete problem?
- Which documents must be prepared and submitted?