Ducts for gas or water pipes or cables passing through walls comprise circular frame divided into three by radial bars, into which compressible seals fit which consist of flexible pads between two plates fastened together by bolts

摘要

Ducts for gas or water pipes or cables passing through walls comprise a circular frame divided into three by radial bars. Compressible seals fit between these which consist of flexible pads (3.5 - 3.7) mounted between two plates (3.3, 3.4). These are fastened together by bolts (3.1) which compress the pads as they are tightened.