Electronic square root error indicator

• US 4,654,813 A
• Filed: 03/09/1984
• Issued: 03/31/1987
• Est. Priority Date: 03/09/1984
• Status: Expired due to Term

• Current Assignee: Southern Gas Association Pipeline And Compressor Research Council
• Original Assignee: Southern GAS Association
• Inventors: Edlund, Carl E., Sparks, Cecil R.
• Primary Examiner(s): Krass, Errol A.
• Application Number:
  US06/588,113
• Time in Patent Office: 1,117 Days
• Field of Search: 364/510, 364/558, 364/571, 364/752, 73/861, 73/861.02, 73/861.03, 73/195, 73/196, 73/861.42, 73/861.43, 73/861.44, 73/861.48
• US Class Current: 702/198
• CPC Class Codes: G01F 1/50 Correcting or compensating means

Abstract

An apparatus for determining a square root averaging error for a differential pressure orifice meter while measuring volumetric fluid flow in a closed medium including input circuitry that provides an input signal corresponding to the instantaneous differential pressure measured at the orifice plate and logic circuitry connected to receive the signals from the input circuitry for computing the square root averaging error for the orifice meter over a selected time interval. Also disclosed is an apparatus for measuring volumetric fluid flow in a closed medium that includes input circuitry for providing an input signal corresponding to a differential pressure at an orifice located within the closed medium and logic circuitry connected to receive the input signal, compute a square root of the corresponding differential pressure and provide an output signal corresponding to this square root.

Claims

1. An improved square root error indicator apparatus comprising:

(a) a differential pressure transducer means for producing analog signals representative of differential pressures of fluid flowing through a closed medium orifice;

(b) an analog to digital converter means operatively connected to the differential pressure transducer means for converting the analog signals to digital signals; and

(c) a digital computing means responsive to the digital signals for producing square root error signals, said digital computing means including a data processing means and an instruction means, said processing means responsive to instructions of the instruction means for;

producing signals representative of the square roots of the differential pressure signals;

accumulating the differential pressure values and the square root values of the digitized signals for a preselected time;

averaging the accumulated differential pressure values and the corresponding square root values thereof;

determining the square root value of the average differential pressure;

determining the difference between the square root of the average differential pressure and the average of square roots of the differential pressures; and

dividing the difference by the average of the square roots of the differential pressures whereby the square root error is produced.

2. An apparatus according to claim 1 wherein said apparatus further includes display means connected to said digital computing means for displaying the square root error.

3. An apparatus according to claim 2 wherein said apparatus further includes a time interval and sample rate input means connected to said digital computing means for providing external control of the computation of the square root error.

4. An apparatus according to claim 3 wherein said time interval and sample rate input means is for inputting a time interval longer than any pulsation frequency time interval of fluid flow.

5. An apparatus according to claim 3 wherein said time interval and sample rate input means is for inputting sample rate signals at a frequency greater than twice any fluid flow pulsation frequency.

6. An apparatus according to claim 1 wherein said apparatus further includes a self-contained power means for supplying electrical power to said apparatus.

7. An apparatus according to claim 1 wherein said differential pressure transducer means is a wide band differential pressure transducer.

8. An apparatus according to claim 1 wherein said data processing means is further responsive to instructions of the instruction means for multiplying the square root error signals by 100 whereby the square root percentage error is determined.

9. An apparatus according to claim 1 wherein said digital computing means further includes first and second accumulators for accumulating, respectively, the differential pressure and the square roots thereof over a preselected interval of time.