Fire resistance requirements for conveyor belts intended for underground use are summarized in DIN EN 14973 while belts for general purpose use are described in DIN EN 12882. Belts are distinguished according to their intended application area into five classes for DIN EN 14973 (A to C2) or ten categories for DIN EN 12882 (1 to 5C). For example, class B1 is explained as „general use, only hazard being limited access and means of escape, plus a potentially flammable atmosphere. No secondary devices necessary“. The actual class or category is chosen on basis of a hazard assessment done by the end user – test specifics and test requirements then depend on the intended class. Up to four different tests need to be passed to fulfill fire safety requirements.

According to DIN EN 12881-1 method A, a test sample with 2 m length and full width is put on a frame and is then impinged with an 80 kW propane burner from beneath. If tested according to method B, a sample with 2.5 m length and full width is impinged parallel from top and bottom. The reason for this being that DIN EN 12881-1 evaluates the fire spread. This means that a belt has to fully ignite on the one hand and on the other hand flames have to decrease by itself until they are eventually self-extinguished. That is why method B has to be conducted if a full ignition could not be achieved with method A. An alternative to method B is method C: a sample (1,500 mm x 230 mm x thickness) is put in a laboratory scale fire testing tunnel (1,676 mm x 460 mm x 460 mm) and is impinged with a six parts gas burner over 50 minutes. The undamaged remaining length serves as evaluation criteria. Finally, method D is very similar to method C, the differences being other dimensions of the test rig (2,100 mm x 350 mm x 350 mm) and the sample (1,200 mm x 90/120 mm x thickness) as well as using the burner for 15 minutes only.

DIN EN 14973, class C2

In addition, to achieve class C2 according to DIN EN 14973 a large scale fire test with an 18 m specimen (full width) is mandatory. The belt is exposed to a 300 kg wood fire (power output approx. 3.3 MW), so that it will ignite eventually. The requirement is for the flames to not spread more than 15 m leaving at least 3 m of belt undamaged. Class C2 is only required by German coal mines in order to keep the safety level of a former German DIN standard.

The belt’s electrical conductivity is assessed according to DIN EN ISO 284. Although this does not directly have anything to do with fire, static charges need to be avoided so that there is no threat of sparks. With two circular electrodes the conductivity is measured and it needs to be below 300 MΩ.

The objective of this Australian standard is to contemporize requirements for fire resistant and antistatic conveyor belting to ensure safe belting is supplied to industry. It was initially developed for the underground coal mining industry and has been contemporized to reflect requirements for fire resistant and anti-static conveyor belting and accessories as may be required for use in potentially explosive atmospheres.

The standard requires five tests in order to classify individual belts or belt ranges: AS 1334.9 gives a test method to determine antistatic properties. AS 1334.10 describes the so-called finger burn test during which a 150 mm x 13 mm specimen is mounted horizontally and impinged with a Bunsen burner for 60 seconds. Any afterflame times are registered. Values are determined with and without belt covers.

The drum friction test according to AS 1334.11 evaluates the belt’s properties (glowing, flames) when objected to friction. The maximum drum temperature is recorded and assessed.

The so-called gallery test is described in AS 1334.12. Here, 2 m belt samples are impinged by an 80 kW gas burner and the belt’s property to self-extinguish is determined.

Lastly, the belt’s oxygen index according to ISO 4589-2 has to be identified as well. The value describes a general material property (fingerprint). A high oxygen index correlates to a high ignition resistance. Values are determined with and without belt covers.

For conveyor accessories (e. g. scraper blades, ploughs or splicing materials), the finger burn test (AS 1334.10), the oxygen index test (ISO 4589-2) and an antistatic test (e. g. AS 1334.9) have to be passed.

In order to issue a belt for registration, e. g. with New South Wales Department of Industry, any belt has to pass an initial type testing. Those tests have to be repeated every 5 years.

Additional to the test report a so called certificate of conformance has to be supplied for a belt registration. This verifies the belt’s conformity to AS 4606.

DMT holds an approval from New South Wales Department of Industry to carry out above tests and to issue the certificate of conformance.