The drum friction test simulates a belt slipping over a jammed pulley, or a pulley rotating under a stationary conveyor belt. This measures whether the surface temperature remains under a required maximum after a specific time and under a specific tension. Generally a rubber conveyor belt can produce a pulley surface temperature of up to 500°C (930°F). The visual appearance of flame or glow is not permitted.
An electrostatic charge may build up on the conveyor belt surface and iginite a mixture of flammable gases and air. Therefore the surface resistance of the conveyor belt covers has to be below 300 MOhms.
Conveyor belts must not propagate fire. In order to determine whether a conveyor belt fulfills this requirement, it is ignited by a propane burner. After the ignition source has been removed, the flames must self-extinguish within a certain time frame or within a certain distance. A typical sample for this test is 2 m long at full width.
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 flame and glow has to be within a specified time limit.
Some countries have even more stringent requirements, for instance regarding the belt's toxicity, hygiene or cover roughness.
The exact specifications can be found in the relevant standards.
It is obvious that not every single belt can be tested as per the above procedures. Therefore a kind of finger print method was developed in Europe:
This method is an effective and inexpensive quality control. It determines the minimum concentration of oxygen that will support combustion of a specific belt sample. The result of the approved belt must comply with any supplied belt of the same type..
The requirement in the United States, in foce until the end of 2009, is quite simple
A small piece of a belt is held over a Bunsen burner flame and the duration of the belt's afterglow must be less that a specified maximum time.
This test, which was implemented as per the 1969 Federal Coal Mine Health and Safety Act, is similar to a standard that was in force in Europe until the mid 1970's for underground conveyor belts (fire resistant, grade K or S). Later, these conveyor belts have only been allowed to be used in above ground applications.
The new test apparatus as per MSHA 30 CFR 14.
The belt sample size is 9 x 60 in (229 x 1524 mm).