Compliance with directives of the European Union (E.U.), including Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE), has been the driving force behind restricting the use of heavy metal substances used to produce certain electrical and electronic equipment, such as IT and telecommunications equipment, lighting, electrical and electronic tools (with the exception of large-scale stationary industrial tools), and monitoring and control instruments. Although limited to the E.U. at this point in time, RoHS compliance affects the global supply chain even for products not seemingly impacted by the legislation — and the likelihood that the United States will follow suit with similar directives at some point is probable.
As RoHS goes into effect July 1, 2006, more attention is also being paid to products made with halogenated compounds (i.e., fluorine, chlorine, bromine, iodine, and/or astatine). The concerns of governments, companies, and individuals are to ensure the safety of persons and equipment from toxic and corrosive gases in the event of fire. From an environmental standpoint, there are concerns that some halogenated materials have potential to harm the environment if not disposed of properly at the end of a product's life.
To eliminate or reduce these risks, alternative non-halogenated products are available from electrical and electronic product manufacturers. However, as the need for these “halogen-free” products grows, confusion exists among those who want to specify their use. Questions that commonly arise as halogen-free materials are discussed include:
- Why are halogenated materials common in many electrical products today?
- What are the issues with halogens, and why use a halogen-free product?
- What does the environment have to do with halogens?
- How do I really know if a product is halogen free?
As an individual involved in the design, specification, or construction of electrical or networking equipment, you should understand the significance of halogen-free materials and be aware of your options for wire and cable management because what you do not know can harm you — and your customers.
Halogenated materials. Halogens are five non-metallic elements found in Group 7 of the periodic table. Halogen means “salt former,” and compounds containing halogens are called “salts.” One of the most common halogenated materials used in plastic product manufacturing today is poly vinyl chloride (PVC). General-purpose electrical applications often use PVC or other halogenated material products because many are inherently flame retardant, a wide range of material grades are available to affect product performance characteristics, and these materials are often lower in cost compared to alternatives.
More specialized halogenated materials can also serve more demanding applications. As an example, fluorine-derived fluorinated ethylene propylene (FEP) provides extremely high heat resistance when used in the insulation of plenum-rated communications cabling, which limits its combustion in a fire. FEP can withstand temperatures up to 800°F before it begins to break down and is also an extremely efficient electrical insulation, which is important for data cables. FEP has largely replaced PVC products in building risers.
Halogenated compounds are the materials of choice today for cabling insulation and electrical components due to the abundance of raw materials on the market, relatively low material cost, and desirable product properties.
Fire safety concerns. The concern over halogenated plastic materials is that these materials can release corrosive and toxic gases if they are ignited in a fire. The corrosive element of these gases has the potential to damage electronics in nearby areas and can be hazardous to persons if they cannot easily evacuate from the fire area.
Equipment corrosion is of particular concern in enclosed environments with a significant amount of expensive electronic devices such as semiconductor manufacturing facilities or phone switching stations.
The toxicity of smoke is of highest concern within spaces occupied by persons where means of escape are limited or hampered. This typically includes mass transit rail cars, large ships, and offshore oil and gas platforms.
With these heightened safety concerns in mind, consideration may be warranted for these two material choices, when available:
1) Use specialized halogenated material products with an extremely high ignition temperature to prevent or limit the amount of gases released in the event of fire.
2) Use non-halogenated material products (a.k.a., halogen free, zero halogen, no halogen, 0H, or ZH) that may ignite in a fire but will not release any toxic or corrosive gases.
With regard to fire safety, another key specification factor to consider is the flame rating, or a material's ability to sustain and spread fire. A typical test method for electrical components is UL94, which provides a rating of the material at a specified thickness, based on performance characteristics (rating scale is from HB to V-0). A halogen-free wiring duct (or other product) with test results at the optimal test rating, would be classified as V-0.
It should be noted that based on the application, other factors often play a role in material selection. An example with wiring duct is when the product is used in an uncontrolled temperature environment. This is especially true in outdoor utility enclosures, where the interior temperature may rise above the continuous use temperatures of most general-purpose PVC products. In this specific case, halogen-free wiring duct has an advantage of higher continuous use temperature ratings than PVC, typically up to 95°C (203°F).
The use of halogen-free products will continue to be directed by industry initiatives and legislation aimed at protecting the environment and at enhancing fire safety and fire damage prevention. When specifying products, remember to consider the installed environment and the selection of products available on the market. Taking this action can ensure the protection of your equipment and improve life safety for those around it.
Michael Berg is a business development manager at Panduit Corp., Tinley Park, Ill.
Typical Applications Using Halogen-Free Wiring Duct
Oil, gas, and petro-chemical facilities
- Offshore petroleum and gas platforms
- Land-based facilities
- Floating production storage operations (FPSO) ships
- Merchant ships
- Mass transit rail cars and stations
Telco, CATV, electric utilities
- Power generation facilities, machinery
- Outdoor utility enclosures
- Data centers