| 摘要 |
The present invention is concerned with a controlled sampler device which draws a gas through a contaminant collection device. The controlled sampler comprises an inlet to the sampler; a pump adapted to draw a gas through the inlet; a reference element that provides a reference signal; a feedback element with an output; a differential pressure transducer to compare the reference signal with the feedback signal to provide an error signal that is linearly related to selected and measured values; an integrator with an input connected to the output of the differential pressure transducer and to a summer; and means between the differential pressure transducer and the summer to provide a signal to the summer which is proportional to the error signal, which is passed to a driver which regulates the speed of an electric motor to change the flow rate to reduce the error signal to a null.
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