Spark extinguishing systems are designed for the detection and extinguishing of sparks.

Sparks and embers can act as ignition sources for a fire or explosion.

One spark that is allowed access to a dust collector that handles combustible dust is enough to trigger a dust explosion. Using the transport system, embers and sparks can be quickly transported from process machines to a storage warehouse or filter and start a violent fire. Instead of trying to contain and deal with fires and explosions, the purpose of fire extinguishing systems is to intervene early, by detecting and extinguishing ignition sources before they develop.

Spark extinguishing systems mainly consist of; spark detectors, a control unit, alarm module and switch off automatics with pressure boosting systems.

Avoidance of ignition sources

If a dangerous explosive atmosphere cannot be prevented from forming, ignite this dangerous explosive atmosphere. This can be done by means of protective measures, which aim to prevent the presence of ignition sources or reduce the likelihood of such being present. In order to be able to determine effective protection measures, one must have knowledge of the different types of ignition sources and their function. The likelihood of a hazardous explosive atmosphere and a source of ignition occurring at the same time and place must be assessed and the extent of protective measures derived therefrom.

The most common sources of ignition of an explosive atmosphere are:

Open flames such as welding, use of cutting torch, roofing torch and tobacco smoking

• Static electricity
• Warm surfaces
• Mechanical sparks
• Electrical installations
• Chemical reactions (self-ignition)

Open fire

Open fire such as welding, tobacco smoking, use of cutting torches and the like. and is an effective ignition source. Arcs from welding and larger glowing solid particles are also effective sources of ignition.

Static electricity

Charging takes place when there is contact and relative movement between the materials, eg with solid materials rubbing against each other, rubber conveyors running, flow, stirring and bottling of liquids and powders.

Hot surfaces

If the surface temperature of equipment reaches the ignition temperature (MIT), the substance ignites, typically 100-800 ° C. Hot surfaces occur partly during normal operation, eg on an electric motor, partly during equipment failure, eg a ball bearing that runs hot, or parts that tear against each other, eg in defective conveyors.

In fact, we are talking about two kinds of MIT (Minimum Ignition Temperature): MITlayer and MITcloud

A resting layer of dust on a hot surface can ignite at temperatures around 200-400 ° C. (MIT Layer), which is the temperature that can start an ember fire in a dust layer. Pay attention to electrical installations, heating systems, lamps, machines and equipment that can become hot. The temperature is usually stated at 5 mm layer thickness. With dust layers above 5 mm, the temperature drops drastically.

The minimum ignition temperature (MITcloud) is the lowest temperature on a hot surface that will cause a dust cloud instead of a dust layer to ignite and scatter flame

For plant parts, such as dryers, testing the minimum ignition temperature is important to prevent a dust explosion that may occur through contact with a hot surface. The maximum internal temperature is generally limited to two-thirds of MIT. For example, a dust with a MIT of 450 ˚C would require a maximum operating temperature in the drying process of 300 ˚C, giving a safety margin of 150 ˚C.

Mechanical sparks

Mechanical sparks are actually glowing metal tiles that are torn off by, for example, impact, friction, tearing, grinding or the use of cutting discs. Rusty iron and certain light metals such as aluminum, magnesium, titanium and zirconium have an easy time forming sparks by friction, whereas e.g. steel, stainless steel, cast iron and copper have difficulty forming sparks. However, certain types of stainless steel can tear against each other, forming sparks. When cutting and grinding with eg angle grinder, most materials can form dangerous sparks.

Mechanical sparks can originate from the system itself, eg parts that tear against each other, from foreign bodies in the material being handled, eg stones or metal pieces, or from the use of hand tools and the like. Sparks from hand machines – such as an angle grinder are a possible source of ignition. At sawmills and mills, one must be aware of sparks that can lead to smoldering particles, which are passed on to dust filters and silos.

Electrical installations

Electrical installations can cause sparks and hot surfaces that can act as ignition sources. Electric sparks occur in connection with the closing and breaking of circuits and are very effective ignition sources. Even at low voltages, such as in measuring instruments and mobile phones, dangerous sparks can form.

Chemical reactions (self-ignition)

Some products can be stored in silos or the like. develop so much heat that it can lead to self-ignition. Here it is important to know the properties of raw materials and finished products, so that you can avoid temperature and pressure conditions as well as fat and water content, which leads to risky heat development.

Cereals, flaxseed / linseed oil, soybean meal, rapeseed, sawdust containing organic oils, fishmeal and coal dust are examples of known substances that can ignite spontaneously at normal ambient temperature.

Gases and dust mixed with air are only explosive within certain concentration limits. Under certain operating and ambient conditions, it is possible to remain outside these explosion limits.

In the case of dust, it is more difficult to avoid explosive mixtures by limiting the concentration. If the dust concentration in the air is below the lower explosion limit, dust deposits are formed by the dust particles sinking if there is not sufficient air movement. These deposits can be swirled to create explosive mixtures.

Particularly in filters, dust particles are excreted and dust accumulations are formed, which can be associated with a significant fire and explosion potential.

Spark extinguishing systems are designed for the detection and extinguishing of sparks.

Sparks and embers can act as ignition sources for a fire or explosion.

One spark that is allowed access to a dust collector that handles combustible dust is enough to trigger a dust explosion. Using the transport system, embers and sparks can be quickly transported from process machines to a storage warehouse or filter and start a violent fire. Instead of trying to contain and deal with fires and explosions, the purpose of fire extinguishing systems is to intervene early, by detecting and extinguishing ignition sources before they develop.

Spark extinguishing systems mainly consist of; spark detectors, a control unit, alarm module and switch off automatics with pressure boosting systems.