Ammonium Phosphate-Based Semi-Rigid Intumescent Board – SA-3
SA-3 is an ammonium phosphate-based semi-rigid intumescent board engineered for passive fire protection around fire door hardware — latch cases, hinges, locks, and inspection windows. It expands 40x in volume at 280°C, forming a dense microcellular insulating foam with multidirectional expansion and negligible expansion pressure — critical for applications where mechanical force could damage precision hardware components. Thickness range 0.6–2mm. Available in custom strip widths and lengths with self-adhesive backing.
Technical Specifications
| Parameter | Value |
|---|---|
| Product Model | SA-3 |
| HS Code | 3920999090 |
| Base Material | Ammonium phosphate (inorganic) |
| Rigidity | Semi-rigid |
| Thickness Range | 0.6–2mm |
| Max Width | ≤2,100mm |
| Activation Temperature | 280°C |
| Free Expansion Ratio | 40x volumetric (350°C, 20 min, 2mm sample) |
| Expansion Direction | Multidirectional (foam formation) |
| Expansion Pressure | Negligible — no mechanical pressure generated |
| Water Resistance | Indoor use — avoid prolonged contact with water |
| Color | Standard available; custom colors on request |
| Asbestos Content | None |
Why Zero Expansion Pressure Matters for Hardware Applications
Standard graphite intumescent strips and sodium silicate boards generate significant expansion pressure when activated — useful for sealing pipe penetrations and door gaps, but potentially damaging to precision-machined hardware components installed in tight recesses.
SA-3’s ammonium phosphate chemistry expands into a soft, multidirectional microcellular foam without generating the directed mechanical pressure seen in graphite or sodium silicate products. This means:
✓ Latch cases and lock cylinders are not deformed under expansion force
✓ Hinge barrels and pivot mechanisms remain functional until temperatures require passive protection to activate
✓ The foam seals gaps between hardware surfaces and the door/frame assembly — blocking smoke and flame passage without damaging functional components
This characteristic makes SA-3 the standard solution for fire door hardware protection where other intumescent materials are unsuitable.
Typical Applications
✓ Latch case and lock body recesses in fire-rated doors
✓ Hinge rebates and pivot housing in timber and steel fire doors
✓ Inspection window frames and glazing bead gaps
✓ Narrow partition gaps and structural joints
✓ Any application requiring intumescent protection without expansion pressure on adjacent components
Processing & Supply
SA-3 can be processed into a variety of strip widths at room temperature. Self-adhesive backing is available for easy installation in hardware rebates without adhesive application on site.
Custom colors available on request — standard product is supplied in natural off-white; other colors can be specified for aesthetic matching with door hardware finishes.
Packaging:
– Cut strips and small pieces: packed in cartons
– Full boards: packed in wooden cases
Frequently Asked Questions
Q: Can SA-3 be used in the same door assembly as SF-7?
Yes. In a typical fire door assembly, SF-7 is used in the door leaf rebate for gap sealing, while SA-3 is used in hardware recesses for latch and hinge protection. Both products are complementary and compatible within the same assembly.
Q: Why does SA-3 activate at 280°C rather than a lower temperature?
Ammonium phosphate decomposition chemistry requires higher temperatures than sodium silicate to initiate foam formation. For hardware protection applications, the 280°C activation threshold is appropriate because the hardware itself provides a degree of thermal shielding before temperatures reach this level in a standard fire test.
Q: Is SA-3 suitable for outdoor or damp environments?
No. SA-3 is specified for indoor applications only. Prolonged exposure to water or moisture will degrade the material. Protective encapsulation is required for installation near wet areas.
Q: Can you supply SA-3 with custom color to match our door finish?
Yes. Custom color formulations are available. Please provide a color reference (RAL or Pantone) and your required quantity for a quotation.
Q: What is the minimum thickness available?
SA-3 is available from 0.6mm thickness — suitable for very narrow hardware recesses where thicker intumescent materials cannot be accommodated without modification to the door or frame.
[→ SF-7 Sodium Silicate Board – rigid board for door gap sealing]
[→ HGYY-BW710 Intumescent Strip – door & window gap sealing]
[→ View All Intumescent Insulation Boards]