| 摘要 |
A process fluid flow-rate sensor adapted to actuate a control circuit or an alarm when the sensed rate falls below or exceeds the critical limits of a predetermined range. The sensor includes a leak chamber operating in conjunction with a main drain line, in an arrangement in which the fluid to be sensed first flows into the leak chamber. The leak chamber has an orifice through which fluid passes therefrom through a leak tube into the main drain line. The arrangement is such that should the flow rate be above a critical minimum value, the filling rate in the chamber will exceed the leakage rate thereof whereby after the leak chamber is completely filled, the fluid then directly passes into the main drain line, whereas when the flow rate falls below the critical minimum value, the leak chamber empties. Mounted for vertical movement in the leak chamber is a float provided with a switch actuator. The float, when the leak chamber undergoes depletion as a result of a flow rate below the minimum critical value, drops to a point at which the switch actuator trips an associated switch to actuate an alarm or control circuit. To sense a flow rate exceeding the maximum critical limit, the switch is arranged to respond to an elevated float position reflecting this condition.
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