摘要 |
<p>In order to determine the nature of fluid passing through a pipe (6), for example whether material being pumped through a pipe is sludge or liquid phase, high frequency ultrasonic pulses from a generator (16) are caused to propagate around a peripheral wall of the pipe to produce ringing in the pipe, and the characteristics of the ringing are measured and compared in a controller (18) with stored data to determine the nature of the fluid content of the pipe. A sludge pump (8) may be controlled according to whether the data obtained shows that the material passing through the pipe is sludge or liquid tunnelling through the sludge.</p> |