| 摘要 |
With reference to Figure 3, a pair of seats (1) for co-operation with a ball-shaped valve member (2) (Figure 4) in forming a ball valve unit (20) is shown, each seat (1) comprising a cup-shaped component of plastics material with a seating surface (3). Each valve seat (1) is provided with means (10) forming a signal path incorporated in a signal system (11), whereby interference with the signal path as a result of wear may be detected. The means (10) comprise a tortuously-disposed optical fibre (12) embedded close to surface (3), within the valve seat (1). One end of the fibre (12) is connected to a light source (13) and the other end to a light receiver (14). The signal system (11) comprises the fibre (12), the light source (13), light receiver (14), connections (15, 16) and alarm initiator (17) with a warning light (18). In operation, the source (13) transmits light signals through the optical fibre (12) to be collected by the receiver (14). In the event that undue wear of the valve seat surface (3) has taken place, (whereby leakage past the valve member (2) will occur), the wear will fracture or damage the optical fibre (12) sufficiently to interfere with the passage of light signals therethrough. This interference will be sensed by the alarm initiator (17) whereby a visible warning signal will be emitted by the light (18). |
