| 摘要 |
<p>Settled sludge 20 is drawn from the bottom of a settling tank 10 by a pump 18, which is controlled by pressure sensing means 26, which effectively monitors the viscosity, and therefore the solids content, of sludge passing through pipe 16, and either stops the pump or diverts the sludge flow when the viscosity falls to a predetermined level. If the level in tank 10 is constant, then a single pressure sensor 26 is sufficient; otherwise two sensors monitor the pressure drop along pipe 16. Only the peak pressure is monitored if pressure varies over the pump cycle. Timers may control the restarting of the pump after it has been stopped. <IMAGE></p> |
