| 摘要 |
An electric air admission controller (17) ("EAAC") for automatically opening and closing an air control valve (46) connected to a vacuum sewage transport conduit (15) with a sewage control valve (20), independently of the level of accumulated sewage upstream of the sewage control valve (20), in order to inject additional air at atmospheric pressure into the vacuum transport lines to apply additional fluid pressure to a mass of sewage therein, and to avoid a waterlogged condition by supplementary transport. In its simplest form, the EAAC system (12) consists of a timer unit (100) which, when activated, causes a solenoid valve (80) to deliver vacuum/subatmospheric pressure or atmospheric pressure to the air control valve (46) to open or close it, respectively by application of differential pressure. Rather than rely upon the timer unit (100) to determine a valve cycling frequency which will, on average, prevent waterlogging, however, a timer-delay module (105) and pressure switch (110) may be added to the system. The EAAC unit (17) cycles the air control valve (46) only when the pressure switch (110) detects an inadequate level of differential pressure in the transport conduit, and the timer-delay unit (105) provides a delay cycle before and after the air transport cycle to avoid unnecessary cycling of the air control valve (46). Finally, the EAAC system (17) may be combined with the sensor-controller module (25), which normally cycles the sewage control valve (20), thereby making special air control valves (46) unnecessary for delivering air to the sewage transport conduit to prevent waterlogging. <IMAGE> |
