bi-directional flow provers - readyflo systemswhat is meter factor? a meter factor is the ratio...
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BI-DIRECTIONAL FLOW PROVERS TRUTH IN MEASUREMENT WITH DIRECT TRACEABILITY TO INTERNATIONALLY ACCEPTED STANDARDS
WHAT IS A PROVER? An open or closed vessel of known volume that is used as a volumetric reference standard for the calibration of meters in liquid petroleum service.
– API Chapter 4 Section 1
WHAT IS ITS PURPOSE? In order to eliminate bias, the calibrated volume of a prover is used to determine a meter factor.
WHAT IS METER FACTOR? A meter factor is the ratio obtained by dividing the actual volume proven by the indicated volume registered by the meter. – API Chapter 4 Note: Factors that can influence the meter’s meter factor are flow rate, temperature, viscosity, wear, and contamination. Proving conditions should match operating conditions in order to maintain the most accurate results possible.
Meter Factor = Prover Volume Meter’s Indicated Volume _________________
BI-DIRECTIONAL PROVER
Launch Chamber Sphere Displacer
Detector Switch
Four-Way Valve
Valve Actuator
Detector Switch Receiving Chamber
PROVER DESIGN REQUIREMENTS • Pipe Size, Schedule & Flange Rating • Sphere Displacer Velocity
• Volume Between Detector Switches
• Four-Way Valve Sizing
• Four-Way Valve Actuator • Pre-Run Length
SPHERE DISPLACER VELOCITY
Note: Minimum Velocity to be no less than 0.5 fps
Max. V = BPH x 0.286 (I.D. [in])
___________ 2 < 5.0 fps _ =
Example: Max. Flow Rate = 3,960 BPH Pipe Diameter = 16”
Max. V = 3,960 x 0.286 (16) 2 = 4.42 fps
PROVER VOLUME • Pre-run length • Distance (volume) between detector switches
Pre-Run Length
Distance between Detector Switches
LENGTH BETWEEN DETECTORS • In order to maintain an
uncertainty of +0.01%, at least 10,000 meter pulses should be collected between detector switches.
Distance between Detector Switches
Example: Meter K-Factor = 2,000 pulses/bbl Min. volume to achieve 10,000 pulses (VBS) = 210 gallons Measuring section pipe inside diameter = 16” Pipe cross sectional area (A) = 1.396 ft Distance between detector switches (VBS/A) = 20.11 ft.
2
FOUR-WAY VALVE SIZING
FOUR-WAY VALVE SIZING
Example: Max. Flow Rate = 3,960 BPH Pipe Diameter = 10”
Max. V = BPH x 0.286 (I.D. [in]) 2 < 15.0 fps _ =
Max. V = 3,960 x 0.286 (16) 2 = 11.33 fps
FOUR-WAY VALVE ACTUATOR • Mechanical • Electrical • Hydraulic Note: The actuator is sized to maintain a reasonable Four-way valve cycle time, or Closed to Closed time (T c-c). This will be used to determine the required prover pre-run length.
LENGTH OF PRE-RUN (RP)
T C-‐C ( ) RP= ___ 2 + 2
1 SEC x Max V __
Pre-Run Length
LENGTH OF PRE-RUN (RP)
T C-‐C ( ) RP= ___
Example: Actuator Speed (T c-c) = 4.9 Seconds Sphere Velocity (Max V) = 4.42 fps
2 + 2 1 SEC x Max V
RP= ( ) + 2 __ SEC x 4.42 1 4.9
2 ___ = 13.03 ft
__
LENGTH OF PRE-RUN (RP)
RP=
Pre-Run Length
13.03 ft