Sep. 30, 2024
Low smoke zero halogen (hereafter referred to as LSZH but also called LSOH, LS0H, LSFH or OHLS) is a material classification that is common to cable and wire casings.
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When exposed to flames and high levels of heat, LSZH materials produce very little visible smoke (compared to PVC and other similar materials) and no halogens, which can be harmful to humans.
There are several similar classifications such as low smoke and fume (LSF) and low smoke varieties of PVC and cross-linked polyethylene (XLPE). Materials with these classifications have similar properties, but often fail to meet prescribed specifications.
This article deals with:
The halogens are a group of elements that can be found in the second column from the right in the periodic table.
Chemically, they are one electron short of having a full shell. This makes the non-metal elements highly reactive. They constantly try and gain an extra electron by reacting with other things &#; including organic matter.
The halogens, displayed in yellow on the below periodic table, can be harmful or lethal to humans.
The main cause of death in a building fire is smoke inhalation, not the flames themselves. Toxic smoke containing halogens is particularly dangerous.
PVC is often advertised as being fire resistant. This means that a high temperature is required for it to start burning. But the problem with PVC is that as it is heated, it gives off more than half of its weight as fumes.
Cable jacketing made of PVC can be dangerous because, when burned, it releases a toxic hydrogen chloride gas &#; chemically like mustard gas. Not only is this harmful to humans but it is also corrosive, and can damage electrical equipment.
Other products of PVC burning, such as dioxin, can cause more &#;slow burning&#; health problems, with the effects staying with victims a lot longer.
Aside from the health effects, the thick acrid smoke that is released by burning PVC can reduce visibility in emergency situations. This can be devastating if, for example, the smoke obscures a pilot&#;s vision during an emergency landing.
PVC cabling can also help fire spread more easily. If lots of PVC wires are bundled together, for example in a group of network cables, travelling between rooms this can help spread flames easily throughout a building and accelerating the destruction.
Regulations have governed the use of PVC in wire and cabling for some time. In certain places, it is ill-advised to use PVC, but it is still common in certain safer settings.
See the difference in combustibility between an LSZH cable and standard cable in the video below.
The first commercial thermoplastic LSZH material for cables was patented by Raychem in . Initially, the material was slow to catch on. But some specifiers saw its value sooner than others &#; notably those in military and transport sectors.
When HMS Sheffield was hit by an Argentine Exocet missile during the Falklands conflict in , the projectile failed to explode when it hit a control room, but a ferocious fire ripped through the ship, killing 20.
The thick poisonous smoke that emitted from electronics on the ship proved far deadlier than the flames.
A fire at King&#;s Cross Underground station in killed 31 when a stray match started a fire underneath a wooden escalator. Again, the thick smoke made it harder for passengers to evacuate and made life more difficult for the emergency services.
These tragedies helped crystallise the need for non-smoking, less toxic wiring in the minds of specifiers. Especially in enclosed spaces such as on war ships and in rail stations, but also more widely across society.
In the UK, low fire hazard cables are used widely, even though there are few statutory requirements for their use.
One important regulation comes from the Construction Products Regulation, introduced last year. From the 1st of July , all cables that are intended for permanent installation in buildings must be accompanied by a Declaration of Performance (relating to the cable&#;s fire resistance) and have a CE marking.
These factors must be considered by building specifiers, who will factor the cable's properties into any risk assessments they carry out. This forms the basis of most regulations in the UK.
More prescriptive regulations govern the use of LSZH cable jacketing in specific industries. Fire resistant cables are widely used in aircraft, trains, ships, submarines, tunnel systems, nuclear power stations and much more. EU regulations require their use in a wide variety of network cables.
Advancements in thermoplastic LSZH made it available to create other accessories for cable management, including LSZH heat shrink tubing, labelling and fixtures.
This meant that more extensive cable management systems could be made from safer materials. Many LSZH cables are ineffective, because although the cables are made from low-smoking, non-toxic materials, other materials used in a cable management system are harmful. This includes things like heat shrink tubing, labels and cable trunking.
Where these cable management systems travel through a whole building it can enable the much faster travelling of fire.
With competitive price and timely delivery, SUNUA sincerely hope to be your supplier and partner.
As with LSZH cables, LSZH heat shrink is low smoking and has no harmful halogens. It is perfect for insulating and protecting sensitive cables, as well as for lightweight harnessing and electrical components in enclosed spaces such as marine, mass transit systems and other sensitive environments.
The most important thing to bear in mind when you are purchasing LSZH products is to know what specifications you are trying to meet. A member of our expert accounts team will gladly offer advice in line with your requirements.
If you have any questions please don&#;t hesitate to get in touch. Call: 723 101.
True low smoke, zero-halogen cables must adhere to stringent smoke density tests (see: BS EN -2) and zero halogen tests (in accordance with BS EN -2-1). Cables that do not pass these tests cannot be classified as LSZH.
Here are some additional tips:
LSZH cable is low smoke halogen free cable. low smoke emission, namely, reduces the production of harmful objects during combustion. Halogen is a toxic gas for humans. Halogen free means no toxic gases are released in the event of a fire.
The LSZH cable can be referred to as environmental protection cable. It is suitable for the rated voltage of 450/750V and below with requirements of high safety and environmental protection of the place.. For example, are suitable for tall buildings, seasons, metros, airports, hospitals, great libraries, gyms, schools, shopping malls and other crowded places.
All or part of the sheath of the LSZH cable, the cover, outer shell and auxiliary materials (lining and padding) are composed of flame retardant material of polyethylene, so it has excellent flame retardant characteristics.
When an ordinary cable burns, releases large amounts of smoke and halogenated acid gases. Halogen acid gas will cause corrosion damage to surrounding electrical equipment. It will also have an adverse effect on rescuers and will not be conducive to rescue work in the event of a fire., which in turn will lead to more serious secondary damage.
Nevertheless, low-smoke zero-halogen cables are manufactured from flame-retardant halogen-free polyethylene material for all or part of the outer jacket and supplemental material. This makes it not only more fire retardant, but also free from halogenated acid gases when burning.
If we want to know where low smoke zero halogen cables should be used, we must know its types and characteristics.
The tensile strength of LSZH flame retardant cables is higher than that of PVC wires and cables usually. In the case of PVC cables, the tensile strength is 1,05 kGF/mm2. While, the tensile strength of low smoke halogen-free cables is greater than 1,2 kGF/mm2.
The LSZH cable has good climatic adaptability, can withstand temperatures from -30°C to 105°C. Besides, It has excellent flexibility due to its hardness. 80 a 90. LSZH cables have high volume resistivity. Y at ω/cm3 is for PVC cables and over ω/cm3 is for Low Smoke Halogen Free cables.
LSZH cables have good resistance to high cable tension. They can withstand voltages greater than 15kV. They also have good elasticity and adhesiveness.
Low smoke zero halogen cables are becoming more popular in military applications, aircraft, railway and maritime. This is because in these areas it is often difficult to ventilate in the event of a fire..
Besides, Low smoke halogen free material is also widely used in high pressure underground tunnels or track marking lines in railway system. when using them, reduces the possibility of harmful gases accumulating in the event of a fire. In case of fire, LSZH cable jacket helps protect personnel from flames, smoke and noxious gases emitted.
Use of LSZH CableLow smoke halogen free cables do not release halogenated acid gases. Nevertheless, ordinary cables contain halogens in their insulating sheath. When a fire breaks out, large amounts of halogenated acid gas. This gas is very corrosive and can increase the spread of a fire..
When the LSZH cable burns, the smoke produced is very small. Instead, ordinary cables emit a lot of smoke during combustion. This hampers the work of the personnel involved and pollutes the environment.. Compared to normal insulated cables, low smoke halogen free cables emit only a very small amount of smoke. The amount of smoke emitted should also be recognized as a low smoke level.
To further improve the electrical performance and mechanical power of the cable and ensure better power transmission quality, the bending radius of LSZH cable is larger than that of ordinary cable during laying construction.
1.Free of halogens: Low Smoke Zero Halogen cables are made with environmentally friendly insulation, coating and special materials. This means that it not only has good electrical and physical-mechanical properties, but also avoid secondary pollution by toxic combustion gases.
2.Low smoke emission and low toxicity: This type of cable uses special new sheathing materials. So, no toxic gases are produced during its production and use and it does not pollute the environment. The use of low-smoke, zero-halogen cables is essential in areas with special needs and where there is a high concentration of people.
3.Environmentally friendly: LSZH cable insulation and sheath do not contain heavy metals harmful to human, like lead and cadmium. And the cable is disposed of without contaminating the soil or water. It is more environmentally friendly than conventional cables. So, also known as green cable.
4.High flame retardancy: Green cables can meet the high fire requirements of buildings. The LSZH wires and cables are not easily combustible and prevent the spread of fire and the spread of disasters.. Especially in high-rise buildings, the use of LSZH cables can increase the rescue time and reduce the danger of harmful gases to people.
The disadvantages of Low Smoke Zero Halogen cable are mainly price and popularity of use.. Although LSZH cables are environmentally friendly, its raw material and technical costs are more expensive than conventional PVC cables. Besides, due to excellent electrical conductivity, the mechanical properties and some other special properties of the ordinary wires, LSZH cables cannot completely replace ordinary cables. Nevertheless, as environmental requirements increase and technology advances, LSZH cables will develop strongly.
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