Low smoke zero halogen (LSZH) cables are made with a special thermoplastic jacket. The use of thermoplastic or thermosetting compounds makes this type of insulation exceptionally flame retardant. LSZH materials are most often used when both fire safety and reliability are critical. LSZH cables are ideal for confined spaces where poor ventilation could be a serious concern. HFFR or halogen-free flame-retardant cables, are cables with special ethylene copolymer blends for jacketing, which provide similar safety benefits as LSZH. For the purposes of this article, we will equate LSZH with HFFR materials.
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In dense urban areas with tunnels full of cable wiring, fire can pose a significant risk according to Science Direct. It is a well-known fact that the most dangerous component of a fire in its early stages is not the flame but the smoke. In areas with limited ventilation, rapid accumulation of smoke can quickly lead to casualties. Even if ventilating systems are present, heavy smoke greatly diminishes visibility and can conceal exits and escape routes.
LSZH is a low-smoke jacketing material that produces little to no smoke when exposed to fires. It is composed of thermoplastic compounds that give off no or minimal amounts of white smoke when exposed to high temperatures. LSZH cables provide excellent physical and electrical insulation properties, while also offering quality flame retardation.
The burning of common jacketing materials produces high amounts of toxic and/or corrosive gases. Most standard cables have halogens such as chlorine, bromine, and iodine in their jacketing. When this sheathing material burns, it produces toxic chemical gases that are dangerous to your health and can cause suffocation. These noxious gases can also combine with water, such as the extinguishing water used by firefighters or moisture within a persons airways, to form corrosive acids. Inhaling these toxic fumes can cause permanent damage to the throat and lungs and lead to complex respiratory problems.
On the other hand, LSZH cables do not contain halogens in their jacketing and therefore produce significantly lower amounts of harmful gases and chemicals when burning. While some gases are still released when the sheathing material is exposed to high temperatures, these are not toxic and do not produce corrosive fumes. Another benefit is that LSZH cables are composed of materials that are environmentally safe.
PVC (polyvinylchloride) jacketed cables are modified with plasticizers to add certain features and characteristics. While PVC generally has very good flame retardancy, it can still emit smoke and toxic gases upon burning. Because of the lack of standardization, there are variations in the fire retardation properties of PVC cables. Different manufacturers use a range of different additives or a combination of them to lower costs while meeting the installation requirements.
Low smoke zero halogen cables, as the name suggests, produce little to no smoke or toxic gases when exposed to heat or flames. LSZH jacketing materials also go through a robust battery of tests before they are approved for industrial or commercial use. These tests evaluate characteristics including electrical properties, flame propagation, smoke measurement, and halogen content measurement.
Additionally, LSZH cables are physically very different from PVC cables. LSZH cables are more rigid because of the flame retarding compounds in the sheathing, while PVC cables can be softer.
LSZH cables are particularly suited for use in confined spaces where people or sensitive electronic equipment are present. The classical examples of such spaces are submarines, aircrafts, tanks, and rail carriages, which is why the military was one of the first groups to take up the widespread use of LSZH cables. In addition to being the standard practice for cabling in the armed services, LSZH cables are also in demand for central offices and other sites with extensive cabling needs.
LSZH cables do not emit toxic gases and maintain visibility even in restricted spaces. They also ensure smooth functioning of electrical devices that may be susceptible to damage from corrosive gases and fumes. Moreover, LSZH cables are self-extinguishing and inhibit the spread of flames to a larger area.
The tests measuring these specifications are conducted under laboratory conditions. The particular values may not be replicated in commercial installations because of external factors.
It is also possible to order custom-made cables that improve on one or more of these properties based on project requirements.
LSZH cabling is routinely used in places with limited ventilation, a high concentration of personnel, or low air density. Mass transit facilities and underground tunnel systems also necessitate the use of LSZH cables. LSZH cables are routinely used in Europe, but their adoption in the U.S. has been slower due to stringent regulations. Locations that benefit the most from the installation of LSZH cables include:
LSZH jacketing can be used to fabricate nearly any type of cable or wiring. Cables that use LSZH insulation and sheathing most frequently include:
Another issue with jacketing materials is the abundance of insulating compounds available. Low-smoke insulation could produce toxic halogens, and zero-halogen insulation could give off heavy smoke on burning. LSZH cabling is, therefore, the most sensible option for applications where both safety and performance are important.
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Remee provides standard and custom cables to deliver specialized products that fit your particular needs. We offer LSZH jacketing solutions for a wide range of cables. Being one of the top wire and cable manufacturers in the country, we offer multiple configurations, composite constructions, and a variety of shielding and jacket coloring/striping options for our cables.
For more information on how Remee can help with your wiring and cabling requirements, browse our selection of products or get in touch with our experts.
Today's growing awareness of the negative effects of halogens releasing large amounts of smoke and toxic gases when exposed to flames has led to a growing demand for low smoke zero halogen cables (LSZH) in many industries. So what exactly is low smoke zero halogen cable?
Low smoke zero halogen (LSZH) ethernet bulk cable is constructed with a halogen-free jacket material, providing a flame-retardant solution well-suited for safety-conscious environments. LSZH ethernet bulk cables come in extensive lengthscommonly up to 500 or feet. The LSZH jacket ensures minimal emission of toxic gases in the event of combustion. In particular, they release less than 0.5% hydrochloric acid (HCl) gas when exposed to fire. Additionally, the absence of polyvinyl chloride (PVC) in cable construction not only enhances fire resistance but also greatly reduces the potential for smoke production.
Benefiting from the characteristics of halogen-free, LSZH ethernet bulk cables are popular in Europe, since the European market requires cables used in LANs, WANs, etc. meet LSZH specifications. These cables indeed comply with IEC and the European flame retardant standard CPR, and their compliance solves customers' worries. So how exactly do LSZH ethernet bulk cables perform better than other ethernet bulk cables?
The following four main advantages prompt us to choose low smoke zero halogen bulk cables.
Good safety performance: Adopting a new type of special coating material that is non-polluting to the environment, almost no acid gases like HCL and less smoke are released when LSZH cables burned, so in those important application scenarios like data centers, they will effectively prevent damage to equipment that is susceptible to corrosion and smoke damage to a certain extent. Moreover, the smoke concentration is low and the visibility is high, thereby reducing the risk of fire hazards.
Good fire resistance: LSZH cables have good flame retardancy and high fire resistance. In addition, LSZH cables are self-extinguishing. When they are used in cabling scenarios such as data centers, their self-extinguishing characteristics can inhibit the spread of flames and protect the scene to a certain extent.
Environmentally friendly: LSZH cables use an environmentally friendly insulating layer, sheath, and special oxygen barrier materials, with no halogen elements nor heavy metal elements such as lead, cadmium, chromium, and mercury that are harmful to the human body and the environment. They will almost not cause environmental pollution and are healthy and relatively environmentally friendly.
Easy maintenance: LSZH cables have a lower friction coefficient than some non-low smoke and halogen-free sheaths, making subsequent maintenance and replacement easier.
Now that we learned the above advantages of low smoke zero halogen cables, benefiting from these advantages, what are the appropriate application scenarios of LSZH ethernet bulk cables?
To leverage their intrinsic properties, the most notable of which is their low emission of toxic gases and smoke, LSZH cables are ideally being implemented in environments where ventilation is scarce, population density is high, or air circulation is notably poor. In such scenarios, the dispersal of smoke and toxicants is hampered, rendering the use of cables containing halogenated compounds (such as those with PVC or FEP insulation) inappropriate and potentially hazardous.
Their elevated safety performance and reduced environmental impact render them exceptionally suited to enclosed public spaces, substantial commercial edifices, and data centers where network reliability and human safety are of utmost priority. LSZH ethernet bulk cables are a conscientious commitment to safety and sustainability in densely populated or poorly ventilated constructions.
Halogen elements constitute Group 17 of the periodic table and are comprised of fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). These elements are characterized by their highly reactive nature due to their ability to gain an electron to achieve a stable noble gas electronic configuration. Halogens are excellent low-cost flame retardants, so sometimes halogenated flame retardants are added to cable polymers to reduce their flammability, the most common of which are PVC ethernet bulk cables.
LSZH bulk cables are conventionally not recommended for use in outdoor environments. Since they are not UV-resistant, waterproof, and weatherproof. When exposed to sunlight, moisture, and extreme temp, LSZH cables will become brittle and will largely shorten their lifespan. If there are outdoor application requirements, you are recommended to choose outdoor-rated ethernet bulk cable jacketed with a double-layer PVC and LEDP.
The main differences between LSZH and low smoke and fume cables (LSF) are materials, safety performance, and cost. LSZH cables use a halogen-free sheath and will not release toxic gases when burned. LSF cables use a resistant coating and modified PVC that still contain halogen elements and release toxic gases when burned. So LSZH cables have better safety performance. Given all this, it is recommended that you choose the appropriate cable based on your actual needs.
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