Sikaflex®-821 FR
Fire-rated interior sealant for rail applications
Sikaflex®-821 FR is an elastic 1-component polyurethane fire-retardant sealant that cures on exposure to atmospheric humidity. It is used for internal joints in the rail industry where the hazard level HL1 or HL2 of the European rail fire standard EN 45545-2 is required.
- Fire-retardant
- Passes EN 45545-2 / R22, R23 HL2
- Free of solvents and PVC
Overview
PRODUCT BENEFITS
- Fire-retardant
- Passes EN 45545-2 / R22, R23 HL2
- Free of solvents and PVC
Areas of Application
Sikaflex®-821 FR is designed for interior sealing applications in the railway industry where special fire-protection requirements acc. EN45545-2 apply. It can be used on a wide variety of substrates and is suitable for permanent elastic seals. Suitable substrate materials are metals, metal primers and paint coatings (2-component systems), ceramic materials and plastics. Seek manufacturer’s advice and perform tests on original substrates before using Sikaflex®-821 FR on materials prone to stress cracking. This product is suitable for experienced professional users only. Test with actual substrates and conditions have to be performed to ensure adhesion and material compatibility.Product Details
| Chemical base | 1-component polyurethane | |
| Color (CQP001-1) | Grey, black | |
| Cure mechanism | Moisture-curing | |
| Density (uncured) | 1.5 kg/l | |
| Application temperature | 10 ─ 35 °C | |
| Skin time (CQP019-1) | 60 minutes A | |
| Curing speed (CQP049-1) | (see diagram 1) | |
| Shrinkage (CQP014-1) | 2 % | |
| Shore A hardness (CQP023-1 / ISO 48-4) | 45 | |
| Tensile strength (CQP036-1 / ISO 527) | 2 MPa | |
| Elongation at break (CQP036-1 / ISO 527) | 250 % | |
| Tear propagation resistance (CQP045-1 / ISO 34) | 9 N/mm | |
| Tensile lap-shear strength (CQP046-1 / ISO 4587) | 1.8 MPa | |
| Service temperature (CQP513-1) |
4 hours 24 hours | -50 ─ 70 °C 120 °C 100 °C |
| Shelf life | 6 months B |
| CQP = Corporate Quality Procedure | A) 23 °C / 50 % r.h. | B) storage below 25 °C |
CURE MECHANISM
Sikaflex®-821 FR cures by reaction with atmospheric moisture. At low temperatures the water content of the air is generally lower and the curing reaction proceeds somewhat slower (see diagram 1).
Diagram 1: Curing speed Sikaflex®-821 FR
CHEMICAL RESISTANCE
Sikaflex®-821 FR is generally resistant to fresh water, seawater, diluted acids and diluted caustic solutions; temporarily resistant to fuels, mineral oils, vegetable and animal fats and oils; not resistant to organic acids, glycolic alcohol, concentrated mineral acids and caustic solutions or solvents.
Application
Surface preparation
Surfaces must be clean, dry and free from grease, oil, dust and contaminants.
Surface treatment depends on the specific nature of the substrates and is crucial for a long lasting bond. Suggestions for surface preparation may be found on the current edition of the appropriate Sika® Pre-treatment Chart. Sikaflex®-821 FR must not to be used with Sika® Primer-207. Consider that these suggestions are based on experience and have in any case to be verified by tests on original substrates.
Application
Sikaflex®-821 FR can be processed between 10 °C and 35 °C (climate and product) but changes in reactivity and application properties have to be considered. The optimum temperature for substrate and sealant is between 15 °C and 25 °C.
Consider the viscosity increase at low temperature. For easy application, condition the adhesive at ambient temperature prior to use.
Sikaflex®-821 FR can be processed with hand, pneumatic or electric driven piston guns.
Tooling and finishing
Tooling and finishing must be carried out within the skin time of the product. It is recommended using Sika® Tooling Agent N. Other finishing agents must be tested for suitability and compatibility prior the use.
Removal
Uncured Sikaflex®-821 FR can be removed from tools and equipment with Sika® Remover-208 or another suitable solvent. Once cured, the material can only be removed mechanically. Hands and exposed skin have to be washed immediately using hand wipes such as Sika® Cleaner-350H or a suitable industrial hand cleaner and water. Do not use solvents on skin.