Glossary

P

PVC

Poly Vinyl Chloride – a thermoplastic material, commonly used in seal assemblies, which may be in varying degrees of hardness or softness as required.

PVCu

Hard “unplasticised” PVC material, widely used in the housings for intumescent seals.

Perimeter seal

A seal located on the long edges and across the head of a door assembly.

Pile seal

A flexible smoke or weather seal element made from short polypropylene fibres and generally incorporated in a rigid PVC or aluminium holder. See also brush seal.

Polymer

A synthetic mouldable material of either rubber or thermoplastic.

Polypropylene

A thermoplastic material widely used in the manufacture of fibres for flexible pile (brush) seal elements.

Pressure Differential

In order to create air movement through any ventilation system it is necessary to create a pressure differential from one end of the system to the other. Though this can be achieved by natural phenomena in the building such as “stack effect” it is more usual to incorporate motor driven fans.