Description
PR-1764 Class B is an electrically conductive, corrosion inhibitive sealant. It has a service temperature range from -67°F (-55°C) to 250°F (121°C), with intermittent excursions up to 360°F (182°C).
The cured sealant maintains electrical continuity in aircraft applications. This material provides excellent long-term EMI/RMI protection. The product is also corrosion inhibitive and protects against the common causes of corrosion on aluminum alloys or between dissimilar metals.
The cured sealant is resistant to prolonged exposure to both jet fuel and aviation gas. PR-1764 Class B is a two-part, nickel filled, manganese dioxide cured, Permapol® P-3 polythioether compound. The uncured material is a low sag, thixotropic paste suitable for application by extrusion gun or spatula.
This sealant has excellent adhesion to common aircraft substrates when correctly primed with PR-148 Adhesion Promoter.
Surface Preparation
Immediately before applying sealant to primed substrates, the surfaces should be cleaned with solvents. Contaminants such as dirt, grease, and/or processing lubricants must be removed prior to sealant application.
A progressive cleaning procedure should be employed using appropriate solvents and a new lint-free cloth conforming to AMS 3819.
(Reclaimed solvents or tissue paper should not be used.)
Always pour solvent on the cloth to avoid contaminating the solvent supply. Wash one small area at a time. It is important that the surface is dried with a second clean cloth prior to the solvent evaporating to prevent the redeposition of contaminants on the substrate. Substrate composition can vary greatly.
This can affect sealant adhesion. It is recommended that adhesion characteristics to a specific substrate be determined prior to application on production parts or assemblies. After the surface has been cleaned, apply PR-148 Adhesion Promoter with a clean brush or a gauze pad.
Care must be taken to obtain a uniform thin coat. At standard temperature, allow the adhesion promoter to dry 30 minutes. It is not recommended to apply adhesion promoter below 45°F (7°C). The sealant must be applied within 8 hours of the application of the adhesion promoter. If this time is exceeded, the surface should be recleaned and the adhesion promoter reapplied.
Do not use adhesion promoter if it contains particles or precipitate.
