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Method and apparatus for measuring mass flow

  • US 5,214,966 A
  • Filed: 04/29/1991
  • Issued: 06/01/1993
  • Est. Priority Date: 10/31/1988
  • Status: Expired due to Fees
First Claim
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1. Method for measuring the mass flow M of a fluid flowing through a pipe having a cross-sectional area A, said method comprisinga) causing an ultrasonic pulse (U1) to traverse a distance (L) in the cocurrent direction of the fluid N times, where N is greater than or equal to 1;

  • b) measuring the time (T1) it takes the ultrasonic pulse (U1) to traverse said distance (L) in the cocurrent direction of said fluid N times;

    c) causing an ultrasonic pulse (U2) to traverse said distance (L) in the countercurrent direction of said fluid N times;

    d) measuring the time (T2) it takes the ultrasonic pulse (U2) to traverse said distance (L) in the countercurrent direction of said fluid N times;

    e) determining the flow velocity (v) of said fluid as
    
    
    space="preserve" listing-type="equation">v=L (N/T.sub.1 -N/T.sub.2)/2 cosθ

    where θ

    is the angle between the longitudinal axis of the pipe and the direction of propagation of said ultrasonic pulse (U1 or U2),f) determining the sound velocity (c2) in said fluid as
    
    
    space="preserve" listing-type="equation">c.sub.2 =L (N/T.sub.1 +N/T.sub.2)/2g) causing an ultrasonic pulse (U1, U2) to traverse a distance x0 in a first material having a density ρ

    0 and thereafter a distance x1 in a second material having a density ρ

    1, before being caused to traverse said fluid;

    h) determining the sound velocity c0 and c1 in said first and said second material, respectively;

    i) measuring the amplitude Ar1 of a part of said ultrasonic pulse (U1, U2) which is reflected in a boundary between said first and said second material and which thereafter again traverses the distance x0 in said first material;

    j) measuring the amplitude At2r1 of a part of said ultrasonic pulse (U1, U2) which is reflected in a boundary between said second material and said fluid and which thereafter again traverses the distance x1 in said second material and the distance x0 in said first material;

    k) determining the density ρ

    2 of the fluid as ##EQU10## l) determining the mass flow M of said fluid as M=v×



    ρ

    2.

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