WATER DRAWCERTIFICATION
C E R T I F I E D C A L I B R AT I O N SCopyright 2016 Certified Calibrations, Inc.
Copyright 2016 Certified Calibrations, Inc.
This presentation will explain:• What a water draw is • Why they are important• How they are performed
Copyright 2016 Certified Calibrations, Inc.
To understand what a water draw is, let’s begin by describing why it is required.
P R O V I N G A N D P R O V E R SH O W P R OV E R S C O R R E C T F O R A C C U R A C Y
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FLOW MEASUREMENT
Typical setup would include:
A. Pipe with flowing product
B. Pressure
C. Temperature
D. Flow Meter
E. Flow Computer
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AB C
D
E
FLOW MEASUREMENT
The flow computer reads information from the temperature transmitter, pressure transmitter and flow meter to calculate a corrected flow rate
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Calculate Flow= 3200/BBLs/Hr.
WHAT IS A PROVE?
A prove is a procedure that validates a measurement system against a known, calibrated volume.
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WHAT IS A PROVER?
A prover is a device with a precise, calibrated volume used to validate precision and correct for accuracy in a measurement system.
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WHAT IS A PROVER?
A prover is a device with a precise, calibrated volume used to validate precision and correct for accuracy in a measurement system.
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Calibrated Volume
WHAT IS A PROVER?
Detector switches are activated as a displacer passes through a calibrated section of the prover — enabling the flow computer to calculate the volume.
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WHAT IS A PROVER?
Detector switches are activated as a displacer passes through a calibrated section of the prover — enabling the flow computer to calculate the volume.
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DetectorSwitch
DetectorSwitch
Displacer
WHAT IS A PROVER?
When the displacer triggers the first detector switch a signal is sent to the flow computer to start counting meter pulses.
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E
WHAT IS A PROVER?
The second detector switch signals the flow computer to stop counting meter pulses and calculate the total volume between detector switches
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A B CD
E
Calculate Volume = 499.905 Gallons
WHAT IS A PROVER?
Any difference between the calculated volume and the known prover volume is used to generate a correction factor (Meter Factor)
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Prover Volume = 500 GallonsCalculated Volume = 499.905
Meter Factor = 1.0002
WHAT IS A PROVER?
This Process is then repeated 10 consecutive times or 5 roundtrips to establish a .050% repeatability between runs.
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A B CD
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WHAT IS A PROVER?
This Process is then repeated 10 consecutive times or 5 roundtrips to establish a .050% repeatability between runs.
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A B CD
E
WHAT IS A PROVER?
This Process is then repeated 10 consecutive times or 5 roundtrips to establish a .050% repeatability between runs.
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A B CD
E
WHAT IS A PROVER?
This Process is then repeated 10 consecutive times or 5 roundtrips to establish a .050% repeatability between runs.
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PROVER CALIBRATION
Because provers are mechanical devices –subject to wear and tear (as well as many other factors) – they need to be recalibrated and certified periodically.
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S O , W H AT “ P R O V E S ” T H E P R O V E R ?C A L I B R AT I N G P R OV E R S
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WAT E R D R AWWAT E R D R AW P R OV E R C A L I B R AT I O N A N D C E R T I F I C AT I O N
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THE FOLLOWING IS A SUMMARY.FOR MORE INFORMATION,PLEASE REFER TO
API CHAPTERS 4.9.1, 4.9.2
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WATER DRAW SYSTEM HARDWARE
A. Water Tank
B. Pump
C. Prover
D. Flow Meter
E. Pressure Gauge
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A
C
D
E
B
WATER DRAW SYSTEM HARDWARE
F. Bypass Valve
G. Test Measure Valve
H. NIST Certified Test Measure
I. Sight Glass
J. Discharge
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F
G
H
I
J
NIST CERTIFIEDTEST MEASURESConstruction: Built to N.I.S.T. 105-3 Standards and API Chapter 4.7
Calibration: Certified using standards traceable to the National Institute of Standards and Technology
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NIST CERTIFIEDTEST MEASURES
A.Fill Tube
B. Neck
C. Sight Glass and Scale
D. Spirit Level
E. Tank
F. Discharge
A
B C
E
F
D
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WATER DRAW SYSTEM CONTROL
A. Displacer
B. Prover Detector Switches
C. PLC
D. Bypass Solenoid
E. Test Measure Solenoid
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C
D
AB
E
WATER BYPASS
Water is circulated through the system (bypassing the test measure) to stabilize Temperature and remove all air before calibration.
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WATER BYPASSThe main bypass valve is closed and a solenoid controlled valve is opened as the displacer is moved into position just before the 1st detector switch .
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PROVER PRESSURE READING
A prover pressure reading is taken before calibration begins.
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33 PSI
WATER BYPASS
When the prover detector switch is activated, the solenoid valve instantly closes—stopping all flow.
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X
FILL TEST MEASURE
The main test measure fill valve is opened to start the calibration process.
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FILL TEST MEASUREAs the displacer makes its way through the prover pipe, the test measure is filled with water until it reaches the sight glass.
A prover temperature reading is made 1/3 of the way during the calibration.
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TemperatureReading:69.0 F
FILL TEST MEASUREAs the displacer makes its way through the prover pipe, the test measure is filled with water until it reaches the sight glass.
A prover temperature reading is made 1/3 of the way during the calibration.
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FILL TEST MEASURE
The main test measure fill valve is closed allowing only the solenoid controlled valve to flow.
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FILL TEST MEASURE
When the displacer triggers the second detector switch, the solenoid instantly stops flow into the test measure.
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X
FILL TEST MEASURE
When the displacer triggers the second detector switch, the solenoid instantly stops flow into the test measure.
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INTERFACE INVENTORYAfter the fill solenoid stops flow into test measure. The displacer continues into the launch chamber for temperature stabilization.
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FILL TEST MEASURE
Using the sight glass and scale. The total volume delivered to the test measure is recorded.
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Read bottom of meniscus
FILL TEST MEASURE
Using the sight glass and scale. The total volume delivered to the test measure is recorded.
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500 Gallons+ 5 in3
TEMPERATURE READING
A temperature reading on the test measure is taken as water is discharged from the measure.
An average temperature sample of at least 1/3 of the total measure volume is required.
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70.1F
FINAL DRAIN TIME
The drain valve must remain open a full 30 seconds after main flow has discharged from a bottom drain measure before closing the drain valve.
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BI-DIRECTIONAL PROVERS
The process is repeated in the reverse direction for bi-directional provers providing a round-trip volume.
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E S TA B L I S H I N G R E P E ATA B I L I T Y
The process is then repeated again at a different flow rate to check the integrity of the prover.
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E S TA B L I S H I N G R E P E ATA B I L I T Y
The process is then repeated again at a different flow rate to check the integrity of the prover.
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E S TA B L I S H I N G R E P E ATA B I L I T Y
Finally the process is completed a third time at the original flow rate to establish repeatability.
API requires all collected values to vary less than 0.020% for a valid water draw calibration
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E S TA B L I S H I N G R E P E ATA B I L I T Y
Finally the process is completed a third time at the original flow rate to establish repeatability.
API requires all collected values to vary less than 0.020% for a valid water draw calibration
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C A L C U L AT I O N S
BMVA in3-Base Measured Volume (Adjusted)
CTDW- Corrected Water Density Effect
CCTS- Corrected compositional Temperature of Steel
WD-Water Draw
WDZB-Water Draw with Prover Dimensional Variation Effects
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BMVA in3 CTDW CCTS WD WDZB
115505.0000 .999976 1.000084 115511.9301 115494.4899
Prover Volume= 499.976 Gallons
(one way)
TEST MEASURES500 Gallon (X2)
Tolerance = 5.0in3
200 Gallon
Tolerance = 1.0in3
100 Gallon
Tolerance = 1.0in3
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5 Tbsp. 1Tbsp. 1Tbsp.
TEST MEASURES50 Gallon
Tolerance = 0.5in3
30 Gallon
Tolerance = 0.25in3
15 Gallon
Tolerance = 0.1in3
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½ Tbsp. ¼ Tbsp. 1/10 Tbsp.
TEST MEASURES5 Gallon
Tolerance = 1.0in3
2 Gallon
Tolerance = 0.5in3
1 Gallon
Tolerance = 0.1in3
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1 Tbsp. ½ Tbsp. 1/10 Tbsp.