DIN EN 45545-2:2013-08, which emerged from the technical specification DIN CEN/TS 45545-2:2009-07 and has been ratified since March 2013 and converted to national law, specifies the “Requirements on fire behavior of materials and components”.
To qualify plastics for certain operating and design classes of rail vehicles, the standard describes testing methods for determining hazard levels (HL) based on different requirement sets (R). In this case, HL 3 corresponds to the highest requirements.
The following tests are performed in order to qualify the plastics for electrotechnical applications:
The un-reinforced polyamides used for Phoenix Contact terminal blocks with flammability rating UL 94 V0 meet the most stringent requirement of HL3 in accordance with the tests described in the requirement sets R22, R23, R24, R25, and R26.
In section 5.2.2.4, DIN 5510-2 “Preventive fire protection in railway vehicles – Fire behavior and fire side effects of materials and parts” requires the insulating materials that fix the energized parts in their position and are not tightly molded must meet the requirement V0 according to DIN EN 60695-11-10, which is comparable with UL 94. As an alternative, an oxygen index OI ≥30% according to DIN EN ISO 4589-2 is required for areas that are not accessible to passengers.
Both requirements are met by the un-reinforced polyamides used for Phoenix Contact terminal blocks with flammability rating UL 94 V0.
To evaluate the surface inflammability of plastics, a “flame spread index” is devised according to ASTM E 162 to provide information on flame propagation under given test conditions.
For this purpose, a sample (152 x 457 x 25.4 mm) is irradiated with a heat source (815 °C) at an angle of 30° and ignited with a naked flame at the top end. During the 15-minute duration of the test, the time in which the flame front reaches two measuring points that are 76 mm apart is determined. The product of this flame propagation time and a calculated heat development factor yields the flame spread index.
In the American railroad sector, the maximum limit value is 35. In this test, the drip behavior of the plastic is evaluated. The terminal blocks from Phoenix Contact achieve a flame spread index of 5, drip without burning, and are therefore well below the maximum permitted values of the Federal Railroad Administration (FRA) of the US Department of Transportation.
The standard ASTM E 662 specifies a procedure for evaluating the specific optic density of the smoke during an open fire or a smoldering fire. For this purpose, the percentage of light transmitted in relation to the burning chamber volume is observed.
A sample (76 x 76 x 25 mm) is placed in a smoke density chamber as defined by the NBS (National Bureau of Standards). The test object is irradiated with a heat of 2.5 W/cm². The following processes are then simulated for 20 minutes:
There are special limit values for the optical smoke density of both processes that are recorded after 1.5 and 4 minutes:
The polyamides used for Phoenix Contact terminal blocks fulfill all the requirements of the Federal Railroad Administration (FRA) of the US Department of Transportation in accordance with ASTM E 662.
SMP 800 C describes the maximum permissible values of poisonous smoke gases when a plastic is burned. In comparison with BSS 7239 (Boeing standard), this standard specifies more precise measuring methods for the qualitative and quantitative determination of toxic smoke gases that result when a test object is completely burned. For this purpose, 6 liter of smoke gas is removed from the NBS chamber during the ASTM E 662 test between the 4th and 19th minute and fed to the analysis.
SMP 800 C limit values of toxic smoke gases in ppm:
The polyamides used by Phoenix Contact are many times below the critical concentrations.
Halogens are, among other things, the chemical elements fluorine, chlorine, bromine, and iodine. One
property of halogen compounds, particularly those containing bromine, relates to the reduction in the degree of inflammability when used in plastics. In the event of fire, poisonous corrosive smoke gases are formed, which can also lead to secondary damages.
For this reason, Phoenix Contact does not use any flame protection systems which contain halogens or other additives. Polyamide, polycarbonate, polycarbonate/acrylonitrile butadiene styrene (PC/ABS) and polyolefines feature halogen-free flame protection systems.
Terminal blocks from the CLIPLINE complete system are made of polyamide 6.6 (PA 6.6) with the fire protection classification UL 94 V0. According to state-of-the-art technology, these polyamides are used halogen-free, with melamine cyanurate as flame protection agent.
Phoenix Contact terminal blocks are therefore, without exception, entirely free of halogens.
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