HFFR (Halogen Free Flame Retardant) materials are mainly campaunds containing Ethylene Vinyl Acetate (EVA), Aluminum Tri Hydroxide (ATH) and Polyethylene (PE). Although some products use Magnesium Oxide instead of ATH as flame retardant, these products are generally not preferred by Turkish material manufacturers since they are very expensive.
It is developed to protect human life, valuable materials and important documents during the fire especially in company buildings, hospitals, shopping malls, hotels, cinemas, underground subway, power stations and fire-related centers, which do not transmit halogen-free flame. During the fire, fire alarm systems, ventilation systems, elevators, warning and directional lights and doors in these buildings should be operating for at least a while. Therefore, the supply and control cables of these systems should be halogen free (HFFR), safety cables.
When we consider reducing the effects of fire for people and objects, we have to calculate the halogen-free, low-smoke density, flame-retardant, flame retardant properties of the material. Thus, we can design an economical material structure according to location and usage.
They do not contain halogen elements such as fluorine, chlorine, bromine and iodine.
When HFFR materials burn, no toxic gas is produced, only water and carbon dioxide are produced.
They do not transmit flame. Polyethylene (PE) and polypropylene (PP) are halogen-free but easily combustible materials.
May extinguish on its own. This is achieved by using special compounds containing aluminum or magnesium hydroxide.
During the fire, the smoke density is very low. Therefore, it is used especially in places where human life may be in danger.
In addition, the function of the cable can be increased to the FE 180 / E90 / PH 180 level using glass fibers, mica and similar tapes and materials.
Although PVC materials provide more flame resistance with additional additives, they produce toxic gases that are harmful to human health when exposed to flame.
Antimony Oxide based materials used in the past are replaced by Aluminum Hydroxide (Al (OH) 3) and Magnesium Hydroxide (Mg (OH) 2) based materials due to their carcinogenic effect.
As it is now known that safer energy and control cables can protect people and buildings, European Union fire regulations regulators are trying to set new safety standards through the upcoming Construction Products Directive (IU).
Halogens are fluorine, chlorine, bromine and iodine. Cables made of polymeric materials such as PVC, NR, SBR, PVDF, PTFE, FEP are materials containing halogen elements. Cables made of materials such as PE, PP, EPR, EVA, SR (Silicone) are halogen-free cables. However, PE, PP, EPR materials can easily catch fire. Flame retardant materials are added to this type of materials to form HFFR (Halogen Free Flame Retardant) type cables.
The following information is intended to give an idea of the basics of HFFR extrusion.
1- Due to the ATH it contains, HFFR materials have a high sensitivity to moisture. Therefore, the original packaging should be opened just before use and the material should be stored in a dry environment.
2- The thermoplastic HFFR material, which is suspected of dehumidification, can be used in the oven, dryer or dehumidifier in the 60-70 C range for up to 4 hours. Thermoset (xlink, crosslinked) materials are not recommended as long-term drying process will evaporate the silane contained.
3- Any masterbatch with EVA or PE carrier can be used to color the material. There are 2 issues that need to be considered when using Masterbatch. The first is that the color masterbatch is moisture-free, and the second is to use the masterbatch at a maximum rate of 1% to reduce the flame retardant properties of the material. It is therefore recommended to use a masterbatch with a high pigment content, rather than using more masterbatches to achieve the desired color.
4oC is the critical temperature threshold for extrusion of 170-HFFR material. 170oC decomposes ATH, a flame retardant additive at heat and releases water. It is this feature of ATH that makes the material flame retardant. ATH, which is exposed to high temperatures during fire, releases water and either extinguishes the flame or prevents its progression. When you burn an HFFR-insulated cable, the bubbles observed on the surface are water that is released. If the critical threshold, 170 C, is exceeded during extrusion, the evaporating water forms a pore and foams in the material, thus adversely affecting the mechanical values and flammability of the material.
5 - You can control the pore in the 2 way; The second method, either by isolating or cutting the sheath horizontally by eye or microscope, is to control specific gravity via the isolate / sheath. The specific gravity 1,50 in the granule should be measured in the isolated / sheath 1,46-1,48 g / cm3. Lower values indicate microfoaming.
6 - There are several reasons why the temperature may rise above 170 C.
6A - Thermocouple, resistance or improper operation of the fans.
6b- High compression ratio of the screw (we recommend compression in 1: 1.12 to 1: 1.20)
6c- Sleeve-throat-head transitions are too narrow or angled
6d- Torpedo (plastic dispenser-heart) channels shallow and narrow
6e- Using strainer
6f- Pressure rise in the head due to non-use of the appropriate extrusion tool.
6g- Using a very large extruder for small sections.
The basic principle of 7-HFFR extrusion is that the pressure and therefore the temperature do not rise uncontrolled in any part of the extruder. The increased pressure causes the material to return to the barrel by the barrier effect, thereby causing an uncontrolled increase in heat due to friction.
8- Non-contact infrared thermometer with mirror temperature
control.
9- Especially during winter months, the first zone of the pond is not heated (30-40 C must be between) and causes shock of the material and sudden decrease in mechanical values.
10 - Keeping the thermal profile low (under 150oC in the head) also leads to a reduction in mechanical values, in particular the elongation at break.
11 - Wet or damp masterbatch will again lead to pore formation.
12- PVC residues in the extruder, or the use of a masterbatch with PVC bearing inadvertently refutes the HFFR material.
13- The performance expected from HFFR insulation and sheath in cable standards is usually 9-10 N breaking strength and 125% elongation and when they reach these values, cable manufacturers generally do not try to improve. Our recommendation is to continue trials and improvements until the mechanical values (11-12 N breaking strength & 150-200% elongation) given in the technical information form published by the manufacturer of the material used. If you accept the limit values as habitually enough, mechanical values will decrease by 10% as a result of a small malfunction during extrusion
the cable produced does not meet the standard and thus leads to scrap. However, the technical data sheet
If you catch 10-15 performance loss due to such failures, your cable will still meet the required standards in the standards.
One of the biggest problems of 14-HFFR cable manufacturers is to pass the vertical burning tests, also called “ladder test başarıyla. The IEC 332-3-C vertical combustion test is as important as the material itself, as well as the cable construction, extrusion conditions and the compliance of the combustion chamber with standards. Because of incorrect construction (such as inter-insulating or gaps between insulation and sheath as a result of the geometry disturbance caused by not using a filler), the gaps extending along the cable will act as a chimney during the test, causing the internal combustion of the cable. Or degradation of ATH as described above due to unfavorable extrusion conditions reduces the flammability values of the cable. Under normal circumstances, every HFFR ladder test with a LOI of 34 or higher is good.
Used to use high compression screws and extrusion tools for 15-XLPE (Crosslinked Polyethylene)
cable manufacturers may think that XLPE extrusion conditions also apply to the thermoset HFFR, as it is “cross-linked.. But this is a mistake. The extrusion conditions of thermoset (cross-linked, x-link) HFFR materials are identical to those of thermoplastic ones.
Fire subject; neglect, accident, ignorance, failure to take protection measures, even as a result of natural phenomena is a life fact. In the event of fires, cables that easily ignite and emit poisonous gases are undoubtedly causing great losses. For cables to be used in areas where fire is likely, flame retardancy, halogen free property, fire resistance property and low smoke density are required. When all these features are evaluated, the use of halogen free type cables in installations is of great importance for life and property safety.