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 person&#;s 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.
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.
Introduction:
&#; LSZH is the short form of Low Smoke Zero Halogen.
&#; These cables are constructed with jacket material free from halogenic materials such as chlorine and fluorine as these chemical have toxic nature when they are burned.
&#; LSZH cables are used mainly in Europe.
&#; It is used in shipboard applications and computer networking rooms where toxic or acidic smoke and fumes can injure people and/or equipments.
&#; Examples of Halogens include fluorine, chlorine, Bromine and Iodine.
&#; These materials when burned produce acidic smoke that can cause harm.
&#; These cables will self extinguish.
Following are the benefits or advantages of LSZH cable:
&#;They are used where people are very near to cable assemblies where they do not get adequate amount of ventilation in the event of fire or there is poor ventilated areas.
&#;They are very cost effective.
&#;They are used in railway systems where high voltage signal wires are used in underground tunnels. This will reduce possibilities of accumulation of toxic gases when cables get fire.
&#;They are constructed using thermoplastic compounds which emit limited smoke with no halogen.
&#;They do not produce dangerous gas when they come in contact with high sources of heat.
&#;LSZH cable jacket helps in protection of people in the event of fire, smoke and dangerous gas due to burning of cables.
Following are the drawbacks or disadvantages of LSZH cable:
&#;LSZH cable&#;s jacket uses high % of filler material in order to offer low smoke and zero halogen. This makes jacket less chemical/water resistant compare to non-LSZH cable counterpart.
&#;Jacket of LSZH cable experiences cracks during installation. Hence special lubricants are needed to prevent it from damage.
&#;It offers limited flexibility and hence it is not suitable for robotics.
If protection of equipment or people is a design requirement, consider low-smoke zero-halogen (LSZH) jacketed cables. They emit fewer toxic fumes than standard PVC-based cable jackets. Typically, LSZH cable is used in confined spaces such as mining operations where ventilation is of concern.
What is the difference between LSZH cable and common cables?
The function and technique parameter of LSZH fiber optic cable is just like common fiber optic cables, and inner structure is also similar, the basic difference is the jackets. LSZH fiber optic jackets is more fire-resistant compared with common PVC jacketed cables, even when they are caught in fire, the burned LSZH cables provide low smoke and no halogen substances, this feature is not only environment protective but the low smoke when it got burned is also important to people and facilities in the fired place.
LSZH jacket is made up of some very special materials which are non-halogenated and flame retardant. LSZH cable jacketing is composed of thermoplastic or thermoset compounds that emit limited smoke and no halogen when exposed to high sources of heat. LSZH cable reduces the amount of harmful toxic and corrosive gas emitted during combustion. This type of material is typically used in poorly ventilated areas such as aircraft or rail cars. LSZH jackets are also safer than Plenum-rated cable jackets which have low flammability but still release toxic and caustic fumes when they are burned.
Low smoke zero halogen is becoming very popular and, in some cases, a requirement where the protection of people and equipment from toxic and corrosive gas is critical. This type of cable is ever involved in a fire very little smoke is produced making this cable an excellent choice for confined places such as ships, submarines, aircraft, high-end server rooms and network centers.
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Every coin has two sides. Since LSZH cables have so many benefits listed above, what are the Cons of the cable?
1. LSZH is more susceptible to jacket cracking. Special lubricants have been made to minimize damage during installation.
2. LSZH jacket has a high filler content, around 50% to provide the required flame and smoke performance. This results in a lower mechanical, chemical resistance, water absorption and electrical properties then non LSZH compounds.
3. The current generation of LSZH cables has not yet established a proven history of long time performance.
The LSZH cables are available with 1, 2, 12, 24 fibers, and variable sub-cable dimensions that support specific termination and routing requirements. They are suitable for halogen free and many international installations. LSZH cable contains no flooding gel and is OFNR Riser rated, is perfect for installation in conduits between buildings and run directly thru risers to a convenient network or dome fiber optic splice closure without a separate point of splice at building entrance.
There are also LSZH fiber optic patch cords available. Both LSZH fiber optic cables and LSZH fiber optic patch cords are required for the Rosh compliant cable assemblies, but Rosh standard is more strict besides it require the cables to be LSZH type. LSZH fiber optic jumper are used widely used in the places where expensive equipment would be damaged if exposed to corrosive gases, and they are also used in crowded areas like commercial centers and sports centers.
The European market is demanding that cables used in LANs, WANs, etc. meet LSZH specification. The IEC -1 governs the Flame Retardant Grade specifications in reference to LSZH cables.Reduction of dangerous/poisonous gases
Essentially, the compound used in manufacturing cables meeting the above specification reduces the amount of dangerous/poisonous gases in case of fire. The main difference in specifications between IEC -1 versus UL® , UL and UL 910 is that the cable under the IEC spec can continue to burn while still emitting very low gases. The UL specs demand that the flame be extinguished, but it can still emit dangerous/poisonous gases.IEC specification
Today virtually all medium and large installations in Europe must meet the IEC specification. Many public authorities are already demanding that new installations must meet IEC -3 which is a more demanding flammability specification for LSZH.
What&#;s the difference between PVC and LSZH cables
Physically, PVC and LSZH are very different. PVC patchcords are very soft; LSZH patchcords are more rigid because they contain the flame retardant compound, and they are aesthetically more pleasing
A PVC cable (made of polyvinyl chloride) has a jacket that gives off heavy black smoke, hydrochloric acid, and other toxic gases when it burns. Low Smoke Zero Halogen (LSZH) cable has a flame-resistant jacket that doesn&#;t emit toxic fumes even if it burns.
LSZH more expensive and less flexible
LSZH cables usually cost more than the equivalent PVC cable, and certain types are less flexible. LSZH cable does have some restrictions. According to CENELEC standards EN, , , screened cables must be halogen free. However, no similar regulation yet applies to unscreened cables.
Where do you run the cable?
Whether you choose a riser (PVC), plenum or LSZH jacket depends on where you&#;re going to run the cable.
PVC cable is commonly used for horizontal runs from the wiring centre. You can use it for vertical runs between the floors &#; but only if the building features a contained ventilation system running through the duct work.
LSZH cable is used between floors in a building. It has a special flame-retardant coating.
A plenum is a space within the building created by building components, designed for the movement of environmental air.
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