FlexiFire HP, HS and HE: Which grade to use when

FlexiFire is a highly flexible, versatile graphite-based intumescent material, manufactured by Vanquish in the UK for a broad and growing range of passive fire protection applications. It first made its name protecting rebated hardware in timber fire doors, but the same properties that make it so effective there – powerful expansion, a stable insulating char, and a flexible material that can be extruded, cut and shaped – make it a strong candidate wherever a gap, void or opening needs to be sealed against fire. 

With over 30 years in the manufacture of graphite intumescent products, and significant investment in new extrusion and conversion machinery, Vanquish is at the forefront of intumescent technology and ready to help you find the right solution for your application. 

What is FlexiFire?

FlexiFire is a graphite-based, extruded flexible-PVC intumescent. At 180°C the intercalated graphite begins to expand with pressure in multiple directions, filling any voids and forming a stable insulating char. The expanded graphite foam resists the passage of hot gases and flame, helping to reduce the spread of fire across a wide variety of applications. The material is inert and, thanks to its PVC composition, has an expected lifespan of over 100 years. 

Why FlexiFire works across so many applications

• Multi-directional expansion – fills irregular gaps and voids rather than expanding in one direction only. 

• Stable insulating char – resists hot gases and flame once activated. 

• Flexible and easy to fit – conforms to recesses, profiles and uneven surfaces. 

• Multiple formats – profiles, strips, sheet up to 1000mm wide, full rolls and bespoke CNC-cut kits. 

• Three levels of expansion – so the grade can be matched to the size of the gap or opening. 

• Long service life – an inert material designed to last for the life of the building. 

Three grades, many applications

Vanquish manufactures three grades of graphite-based intumescent under the FlexiFire® brand – HP, HS and HE. Graphite content rises from HP to HE, and expansion rises with it. The applications below are typical examples rather than a complete list: each grade can be adapted to suit many other fire protection requirements. 

FlexiFire HP

FlexiFire HP is an extruded flexible PVC compound designed to fill small cavities, joints and voids. It has the lowest graphite loading in the range and expands more than six times its original thickness. It is available in a range of profile sizes and in thicknesses up to 5mm. Typical uses include: 

• Specialist linear gap sealing for construction projects 
• Graphite-only perimeter seals 
• Hinge protection, with square and radius profiles to suit different hinge styles 
• Door viewer protection 

FlexiFire HS

FlexiFire HS is a sheet-extruded flexible PVC compound that expands more than 15 times its original volume. It is available in widths up to 1000mm and thicknesses up to 2mm, supplied in full-size rolls or as bespoke pre-cut kits. Because it can be CNC cut to almost any shape, HS is ideal for lining recesses and cut-outs of all kinds. It is widely used for hardware protection in fire-rated timber and composite doors, including: 

• Mortice sashlocks and deadlocks 
• Tubular latches 
• Concealed door closers and concealed hinges 

The same sheet can be converted into custom kits for other components, housings and enclosures. 

FlexiFire HE

FlexiFire HE is the highest-performing graphite intumescent in the range, suited to the most onerous applications and larger openings. It expands over 20 times its original volume and creates a strong, stable insulating graphite char. It is available in various profile sizes and thicknesses up to 5mm. Typical uses include: 

• Penetration sealing 
• Light fittings 
• Fire-resitant Letterplate liners 
• Larger apertures and openings that need high expansion to close 

Is FlexiFire third-party certified? 

Yes. FlexiFire is certified by International Fire Consultants (IFC), part of the Kiwa group, under the SDP20 scheme for intumescent hardware protection in 30 and 60-minute timber applications. Third-party certification requires ongoing auditing to assess the consistency of production, giving the end user peace of mind that the product will perform as specified by the manufacturer. 

Every piece carries a traceability print, so specifiers and inspectors can confirm exactly what has been fitted. For applications outside the scope of this certification, our team can advise on suitability and the supporting evidence that may be required. 

FlexiFire grade comparison at a glance

Have an application that isn’t listed here?

The applications above are the most common, but they are far from the only ones. If you are working on a product, project or detail where a gap, joint, void or opening needs to resist the passage of fire, FlexiFire may well be suitable – even if your application isn’t mentioned in this blog. 

Our technical team works with manufacturers, specifiers, contractors and installers to explore new uses for FlexiFire. We can help you: 

• Choose the right grade and thickness for the gap or void you need to seal 

• Develop custom profiles, shapes or CNC-cut kits for your components 

• Discuss samples for trial fitting and evaluation 

• Understand what testing or assessment may be needed to support your application 

Talk to the Vanquish team now

View the full FlexiFire range, or contact the Vanquish team on 01725 578020 to discuss your application, whether it’s listed here or not.