Thermal Stability Test Apparatus, as per IEC:60811-405.
Model No.: D1013
Thermal stability tests (essai de stabilité thermique, essai de stabilité thermique, prova di stabilità termica) are conducted on PVC, EVA etc. based materials to obtain the behavior of thermal degradation at high temperatures.
During extrusion process many times the changeover takes longer than expected and the previous batch of raw material stays in the screw getting heated by the hot heaters up to a mx temp of 170 deg cel sometimes. As a result of this, cable manufacturers find burnt particles or fish eyes, or contamination on insulation/jacket after the extrusion of cable. This is actually caused by the quick degradation of the compound that was left in side the extrusion screw.
At elevated temperatures, such as those that would be experienced in an indirect fire scenario, the process of degradation Material containing HCL, give off hydrochloric acid (HCl), that consequently accelerates the degradation process. The thermal stability test determines how stable these plastic materials are.
Tests are conducted not before 16 hours after the extrusion of the insulating or sheathing compounds. Thermal stability tests are conducted in accordance with the international standard IEC 60811-1-2 now covered by IEC 60811-405. Test methodology requires glass test tubes 110 mm long, with an outer diameter of roughly 5 mm and an inner diameter of (4,0 ± 0,5) mm, universal indicating paper (pH range of 1 to 10), and a thermostatically controlled heating apparatus for the temperature per the quality of the cable type being tested. The temperature is controlled by heating a solid aluminum block with a digital temperature controller to take care of constant uniform heat throughout the testing. Three samples, of 50 ± 5 mg, are be taken from the jacket or the insulation or directly from the compound granules be tested. Each sample consists of two or three small strips of between 20-30mm. These samples are placed into a glass tube together with a strip of dry universal indicating paper measuring about 15mm long by 3mm wide. The pH paper must protrude out of the highest of the tube by about 5mm. The test samples then placed within the thermal heating equipment (already at the required temperature) and heated for the desired time. Thermal stability testing measures either the time it takes for the universal indicating paper to vary color from a pH value of 5pH to a price between 2- 3pH, or for a specified duration without pH color change, whichever is soonest. the color change point is taken into account to possess been reached when the red coloring of the universal indicating paper characteristic of a 3pH value has just appear. Towards the top of the expected test time, the pH paper is replaced every 5 min to 10 min so the instant of change is best visible. For a cable to fulfill the wants of Thermal Stability Testing, the typical value of the three samples shall not be less than the worth laid out in the quality for that sort of cable.
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