| 摘要 |
Steam leaks in a steam raising boiler are detected by microphones 13a-13f connected to the combustion space of the boiler via long narrow listening tubes 10a-10f. The signal from each microphone is amplified and filtered (14e-14f, 15 and 16) so that there is selectively passed a signal of frequency 4-8 KHz. The resultant signal is supplied to a display 17 with bar charts 18 whose range and bias is set so that (a) at a signal level of less than 74 dB corresponding to normal background noise no signal shows on the display, (b) a signal level of 74-94 dB operates to a first portion of the display range to indicate an abnormality, (c) a signal level of 94-114 dB operates a second portion of the display to indicate the presence of a steam leak and (d) a signal beyond 114 dB exceeds the range of the display and indicates that serious secondary damage is occurring. A colour change indicates the change from (b) to (c). <IMAGE> |
