Apparatus for determining the pulse repetition rate of a fluidic oscillator through which a test gas is flowing

Claim 1

Apparatus for determining characteristics of a test gas comprising: (A) a fluidic astable oscillator having a supply port and alternative state output ports; (B) supply means for applying the test gas as the working fluid to said oscillator supply port, said supply means including: (i) a surge tank coupled between a source of the test gas and said oscillator supply port; and (ii) regulating means for regulating the pressure of the test gas applied to said oscillator supply port; (C) a first pressure transducer for electrically sensing pressure pulses at one of said output ports; (D) a second pressure transducer, said second pressure transducer being disposed in communication with the test gas in said surge tank; (E) a first voltage-to-frequency converter connected to receive the output signal from said second pressure transducer such that the frequency of pulses issued by said first voltage-to-frequency coverter is responsive to the pressure of the test gas within said surge tank; (F) timing means defining a predetermined time period; (G) first counter means for accumulating pulses from said first pressure transducer during said predetermined time period such that, at the end of said predetermined time period, the accumulated count is representative of the pulse repetition rate of said fluidic astable oscillator; (H) first record means for recording the pulse repetition rate at least temporarily; (I) second counter means for accumulating pulses from said first voltage-to-frequency converter during said predetermined time period such that, at the end of said predetermined time period, the accumulated count is representative of the pressure in said surge tank; and (J) second record means for recording the pressure of the test gas in said surge tank at leat temporarily.