Flexible Metal Conduit, Interlocked Gal, LSZH (Low Smoke Zero Halogen) Jacket

LSZH stands for Low Smoke Zero Halogen. The PLTG23LSZH conduit uses an LSZH outer jacket that, when exposed to fire or high heat, produces minimal smoke and releases no halogenated gases such as hydrogen chloride (HCl). In a fire event inside a confined or poorly ventilated space — such as a subway tunnel, ship compartment, data centre, or equipment room — conventional PVC jackets generate dense black smoke and toxic halogen gas that impair evacuation and cause severe corrosion damage to sensitive electronics. An LSZH jacket significantly reduces these risks, making PLTG23LSZH the preferred conduit for life-safety-critical and enclosed environments.

No — LSZH and fire retardancy are two distinct and independent properties. LSZH describes the chemical composition of the jacket material (low smoke emission, no halogen release during combustion). Fire retardancy describes the material's ability to resist ignition and self-extinguish once the ignition source is removed. The PLTG23LSZH is not rated as fire retardant. However, its LSZH jacket ensures that when combustion does occur, the smoke and gases released are far less toxic and corrosive than those from a standard PVC jacket. For applications requiring both LSZH and fire retardancy, please contact Kaiflex at info@flexible86.com to discuss the appropriate product selection.

The PLTG23LSZH uses an interlocked (also called annular or helical) galvanized steel core, in which the metal strip is formed into interlocking rings. This construction provides a larger internal bore relative to outer diameter, making the conduit lighter and easier to bend over long runs. Square-lock construction (used in the PAG13LSZH series) forms the steel strip into a closed square profile, which provides better roundness retention after bending, higher crush resistance, and tighter pull-through characteristics. For most standard wiring runs — including subways, tunnels, and industrial panel wiring — interlocked construction provides sufficient mechanical performance at lower material cost. For installations with tight bending, high transverse load, or machine tool applications, square-lock is preferred.

The PLTG23LSZH conduit achieves two IP ratings depending on the fittings used:

• IP40 — when used with AZ52 or AZ62 series fittings. Protects against solid objects larger than 1mm; no rated water protection.

• IP64 — when used with AZ50, AZ51, AZ53, AZ60, AZ61, or AZ63 series fittings. Complete dust protection and splash resistance from all directions.

To achieve the IP64 system rating, both the conduit and the fittings must be correctly matched and assembled per Kaiflex installation guidelines.

The PLTG23LSZH is rated for operating temperatures from -30°C to +80°C. The lower cold-side limit of -30°C is wider than the -20°C rating of standard PVC-jacketed conduits in the same series (such as the PLTG23PVC), making the PLTG23LSZH suitable for cold storage facilities, outdoor installations in cool climates, and low-temperature industrial environments where standard PVC jackets may become brittle and prone to cracking.

The PLTG23LSZH is primarily specified in locations where low smoke and zero halogen performance is required by safety codes or project specifications:

• Rail and transit systems — metro, light rail, and mainline train wiring in tunnels, platforms, and rolling stock

• Tunnels and underground infrastructure — road tunnels, utility tunnels, and underground cable management

• Marine and shipbuilding — vessel interior wiring in enclosed compartments

• Hospitals and public buildings — areas with high occupancy and limited evacuation time

• Data centres and telecommunications — where halogen gases from combustion would cause severe damage to electronics

• Industrial plants — confined processing areas or equipment rooms where conventional conduit is permitted but LSZH is preferred for safety

The PLTG23LSZH is available in 7 sizes:

Both are interlocked galvanized steel flexible conduits from the Kaiflex AS series sharing identical dimensions, fitting compatibility, and IP ratings. The sole difference is the outer jacket material:

• PLTG23PVC uses a standard PVC jacket: self-extinguishing, UV-resistant, temperature range -20°C to +80°C. Cost-effective for general industrial and commercial wiring where LSZH is not required.

• PLTG23LSZH uses an LSZH jacket: low smoke emission, zero halogen gas release during combustion, wider cold-side temperature rating (-30°C). Preferred for confined spaces, public infrastructure, rail transit, and any environment where fire gas toxicity is a safety concern.

If your project specification or local fire safety regulation requires LSZH conduit, select the PLTG23LSZH. For general outdoor or industrial wiring without specific LSZH requirements, the PLTG23PVC is the standard choice.

The PLTG23LSZH conduit is compatible with the following Kaiflex AS series fittings:

• IP40 system: AZ52 (straight type EMT connector), AZ62

• IP64 system: AZ50 (straight, male NPT threaded), AZ51 (straight, female threaded), AZ53 (90° elbow), AZ60 (straight, quick assembly rotating), AZ61, AZ63

To achieve IP64 ingress protection for the complete wiring system, use the AZ50, AZ51, AZ53, AZ60, AZ61, or AZ63 series fittings. Ensure the fitting nominal size matches the conduit trade size for a correct sealed assembly.