DIN 22118 Textile Layer Conveyor Belts for Use in Coal Mining - Fire Test

The standard “DIN 22118 Textile laminated conveyor belts for use in coal mining - Fire test”, developed by the German Institute for Standardization (DIN), describes fire test methods for textile laminated conveyor belts used in coal mining.

Conveyor belts are a high risk because they have the ability to spread fire long distances. Fires on belt conveyors are most often ignited by mechanical failures such as frozen rollers, and this creates an even greater risk when combined with coal dust.

Several testing methods performed in this context include:

• Drum friction test: This test method simulates a belt sliding over a stuck pulley or a pulley rotating under a stationary conveyor belt. This measures whether the surface temperature remains below a required maximum value for a specified period of time and under a specified tension. Typically a rubber conveyor belt can produce a pulley surface temperature of up to 500 degrees. No visual appearance of flame or glow is permitted in this method.
• Surface resistance test: Electrostatic charge may accumulate on the surface of the conveyor belt and ignite the mixture of flammable gases and air. Therefore, the surface resistance of the conveyor belt covers should be below 300 MOhm.
• High energy propane burner test: Conveyor belts must not spread fire. To determine if a conveyor belt meets this requirement, it is ignited by a propane burner. Once the ignition source is removed, the flames must self-extinguish within a specified time period or a specified distance. A typical sample for this test is 2 m long at full width.
• Propane burner test: The test rig and burner are described in the DIN 22118 standard. Fire protection systems for metallic structures are developed, tested and qualified using constant heat flux tests involving hydrocarbon combustion. During this test, the propane burner produces a large, constant heat flux to simulate a severe fire situation.
• Spirit flame burner test: A small piece of the conveyor belt is held over a spirit burner flame. After a certain time, the burner is removed. The duration of the flame and glow must be within a certain time limit. In some countries, there are more stringent requirements, for example, regarding the toxicity of the belt, its hygiene or the roughness of the coating.
• Limiting oxygen index: It is clear that in practice not every belt can be tested. However, this method is an easy and effective way to check whether the supplied belt complies with the agreed fire safety requirements. This method is an effective quality control. It determines the minimum oxygen concentration that will support combustion of a given sample of belt. The result of the approved belt should be consistent with any belt supplied of the same type.

A mining conveyor belt is one of the most basic components of a conveyor system. It transports ore and other materials from the mining site to processing facilities or loading areas. Conveyor belts are powered by a motor powered by electricity or other power sources.

In coal mining, depending on the application and several other considerations, the composition of the belt may include plastic or rubber compound, fabric materials and steel cables. These belts are supported by rollers that allow them to safely and efficiently transport ore and other materials at a predetermined speed.

Traditional conveyor belts are mainly composed of three layers:

• The top layer or cover on which the product rests during transport.
• The middle layer, also known as the carcass (this layer helps support the belt and the carcass is usually made of metal or woven fabric).
• Bottom cover (part that completes the band structure).

Choosing the right type of conveyor belt is critical to ensuring safe operation. Using the wrong belt can lead to disastrous results and unplanned downtime. The different types of conveyor belts available include:

• Multi-ply: Consists of several layers of fabric separated by rubber that helps reduce impact. Tends to be longer lasting and is used for underground applications.
• Flat warp: Ideal for tunneling applications, mostly used in rock quarries and rock crushers. Impact and tear resistance are two important features with yarn and polyamide on both sides. Flat warp belt can achieve higher groove ability at narrower belt widths and higher values.
• Steel cord: Steel cables running along the entire length of the belt secure these types of conveyor belts used for underground applications.
• Solid woven tapes: These are more popular in Europe and Asia, not used as often in the US.
• Heat resistant: Designed to withstand high temperatures.

In mining operations, it is necessary to first decide on the tensile strength requirement, coating thickness and coating type depending on the material being transported and loaded. In addition, the working environment in which the conveyor carries the material is also particularly important.

Conveyors that move packaging or lightweight materials in temperature-controlled warehouses must have different requirements than conveyors that move heavy products underground in mines and quarries. Therefore, the application and environment should be the two most important considerations when selecting a mining conveyor belt.

Our organization has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also test services in accordance with the standard "DIN 22118 Textile layer conveyor belts for use in coal mining - Fire test".