K-Flex ST Tube Pipe Insulation 25mm Wall

K-Flex ST Tube 25mm Wall is a flexible closed-cell elastomeric foam pipe insulation — also known as AC pipe lagging, refrigerant pipe insulation, or HVAC pipe wrap — manufactured by K-Flex in Italy to EN 14304 standards. The 25mm wall thickness is suited to commercial and high-specification HVAC applications where enhanced thermal resistance is required.

Key Specifications:

• Wall thickness: 25mm
• Material: Closed-cell elastomeric foam (NBR/PVC)
• Thermal conductivity (λ): ≤ 0.040 W/(m·K) at 0°C
• Operating temperature: -50°C to +105°C
• Fire rating: Class 1 (BS 476 Part 7)
• Standard: EN 14304
• Colour: Black
• Country of origin: Italy
• Sold per metre length

Available bore sizes: 12mm, 15mm, 18mm, 22mm, 28mm, 35mm, 42mm, 48mm, 54mm, 60mm, 67mm, 76mm, 89mm, 92mm, 108mm, 114mm, 133mm, 140mm, 160mm, 170mm

Compatible Systems:

• Commercial VRF/VRV refrigerant pipework
• Large-bore chilled water distribution pipework
• Industrial refrigeration pipework
• High-specification HVAC installations requiring enhanced thermal performance

Compatible Brands: Suitable for use on Daikin, Mitsubishi Electric, Fujitsu, Panasonic, Samsung, LG, and all other VRF/VRV and commercial AC systems using copper ACR pipework.

When to Use 25mm Wall Insulation:

• Use where enhanced thermal resistance is required beyond standard 13mm or 19mm wall — typically commercial VRF systems, large chilled water distribution, or industrial refrigeration.
• Prevents condensation on suction lines and heat gain on liquid lines in high-ambient or long pipe run installations.
• The built-in vapour barrier eliminates the need for additional vapour barrier tape on most applications.
• UV-resistant surface suitable for short exposed sections, though aluminium cladding is recommended for long-term external exposure.

Choosing the Right Wall Thickness:

• 9mm — tight spaces, short runs, domestic AC
• 13mm — standard AC and HVAC (most common)
• 19mm — refrigeration and low-temperature systems
• 25mm — commercial and high-specification applications
• 32mm | 40mm | 50mm — industrial and heavy-duty applications

Frequently Bought With:

• K-Flex K-420 Contact Adhesive 250ml — recommended adhesive for joining and sealing K-Flex ST insulation to maintain vapour barrier integrity
• 50mm Self-Adhesive Aluminium Foil Tape — for sealing joints and protecting exposed external sections
• 75mm Premium Aluminium Foil Tape — for wider joint coverage on larger bore insulation

Frequently Asked Questions:

What wall thickness do I need for a VRF/VRV system?

25mm wall is recommended for VRF/VRV long pipe runs and commercial systems where heat gain and condensation control are critical. For standard domestic split AC, 13mm wall is the most common specification.

Is K-Flex ST suitable for outdoor use?

K-Flex ST has a UV-resistant surface suitable for short exposed sections. For long-term external exposure, protect with aluminium foil tape or cladding. For fully external applications, K-Flex Solar is the recommended grade.

What bore size do I need for 3/4" copper ACR pipe?

3/4" (19mm OD) copper ACR pipe requires 22mm bore insulation. Select the 22mm bore variant from the size selector above.

Is K-Flex ST Class O rated?

K-Flex ST carries Class 1 fire classification to BS 476 Part 7. For Class O (BS 476 Part 6 and 7 combined), specify K-Flex ST Class O grade — contact us for availability.

Can K-Flex ST be used on chilled water pipework?

Yes. K-Flex ST is suitable for chilled water systems operating within the stated temperature range. Ensure all joints are fully glued with K-420 adhesive to maintain vapour barrier integrity.