DesignThe Hallite 455 double acting piston seal provides the designer with a premium quality product to fit the industry standard NFPA (T3.19.18-1973) housing.It comprises a bronze filled PTFE face ring, which is pre-loaded by a square section NBR ring. The cap ring is precision machined from a compression moulded billet. Compression moulding of the material offers consistently superior physical properties as compared to automatic moulded products. The machined face ring has chamfered corners for easy installation and a surface finish free from the orange peel effect associated with automatic moulded products. As only the PTFE face ring is in contact with the sliding surface, friction is very low and stick slip movement is eliminated. The housing width allows the designer to use a narrow width piston, but it is recommended that an adequate bearing be mounted on either side of the seal as shown.The Hallite 455 seal is not recommended for applications where it is necessary for the pressurized cylinder to maintain the load in a set position.MaterialsStandard materials are bronze / PTFE with a NBR square section energizer. Contact your Hallite technical representative for special applications and materials.