| 摘要 |
An improved dosimeter designed for individual use that has a filter for collecting particles or vapors present in an air stream being pumped through the dosimeter, a variable drive pump that draws the air stream through the filter, an electric motor coupled to the variable drive pump, an electric power source for the motor, an air reservoir connected to the pump, an orifice position in a tube attached to the air reservoir which creates a pressure drop in the air stream, a differential pressure switch positioned before the orifice that is activated by a change in air pressure and creates a low voltage electrical input signal; an integrator circuit that uses the low voltage input signal of the pressure switch and integrates this signal, an amplifier circuit which amplifies the signal from the integrator circuit and feeds the signal to the electric motor thereby controlling the speed of the motor driving the pump in relationship to the signal generated by the pressure switch to maintain the air stream at a constant flow rate; the improvement that is used therewith is as follows: an accumulator positioned before the variable drive pump retains air and maintains an even flow of air of the inlet of the pump and a pulsation air pressure filter assembly positioned between the orifice and the pressure switch reduces pulsations in the air stream thereby limiting the activity of the switch to substantial changes in air pressure of the air stream.
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