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© Copyright 2007, FMC Technologies Measurement Solutions, Inc. PR0A028I Issue/Rev. 0.0 (7/07) - Slide 1

API Review


API MPMS Chapter 5, Section 1General Considerations

for Measurement by Meters


Introduction5.1.1 The advantages of metering:

Increases the availability of tanks

Leads to display of instantaneous flow rate and volume

Delivers a volume taken from several sources at the same time into one receptor

Delivers a volume taken from a single source into multiple receptors

Can be checked against standards

Simplified Temperature averaging & sampling


1 Block Valve*

2 Differential Pressure Device*

3 Strainer and/or Air Eliminator*

4 Flow Conditioning Element

5 Inferential Flow Meter

6 Straight Pipe

7 Pressure Measurement Device

8 Temperature Measurement Device

9 Temperature Test Well

10 Positive Shutoff Double Block and Bleed Valve

11 Control Valve*

12 Check Valve*

13 Densitometer*

14 Detector Switch

15 Prover

*If Required

API Design ConsiderationsTypical schematic diagram of single Inferential flow meter installation

5.1.4 The installation should provide for proving each meter and should be capable of duplicating normal operating conditions at the time of proving

Note: All sections of line that may be blocked between valves shall have provisions for pressure relief (preferably not installed between the meter and prover).


Meter Performance

5.1.8For custody transfer applications, meters with the highest inherent accuracy should be used and should be proven on site


Meter Proving5.1.9.4.2

•The optimum frequency of proving depends on so many operating conditions that it is unwise to establish a fixed timeor throughput interval for all conditions

5.1.9.4.3 • Proving should be frequent (e.g. every tender or every day) when a meter is initially installed

• After frequent proving has shown that the meter factors for any given liquid are being reproduced within narrow limits, the frequency of proving can be reduced if the factors are under control and the overall repeatability of measurement is satisfactory to the parties involved


API MPMS Chapter 5, Section 8Measurement of Liquid Hydrocarbons

by Ultrasonic Flow Meters Using Transit Time Technology


8.1 – Introduction• This document describes methods for the installation and operation of ultrasonic flow meters (UFM’s) when they are used to measure liquid hydrocarbons

• Ultrasonic meters are inferential meters that derive the liquid flow rate by measuring the transit times of high-frequency sound pulses


8.3 – Field of Application• The field of application of this standard is the dynamic measurement of liquid hydrocarbons

• While this document is specifically written for custody transfer measurement, other acceptable applications may include:

Allocation measurementCheck meter measurementLeak detection measurement


1 Block Valve*

2 Differential Pressure Device*

3 Strainer and/or Air Eliminator*

4 Flow Conditioning Element

5 Ultrasonic Flow Meter

6 Straight Pipe

7 Pressure Measurement Device

8 Temperature Measurement Device

9 Temperature Test Well

10 Positive Shutoff Double Block and Bleed Valve

11 Control Valve*

12 Check Valve*

13 Densitometer*

14 Detector Switch

15 Prover

*If Required

8.6 – Design ConsiderationsTypical schematic diagram of single ultrasonic flow meter installation

Note: All sections of line that may be blocked between valves shall have provisions for pressure relief (preferably not installed between the meter and prover).


8.9.1 – Flow Conditioning• Flow conditioning elements intended to reduce swirl or velocity profile distortion may be required

• The design shall ensure appropriate flow conditioning upstream and downstream (same requirements as turbine meters) unless the meter manufacturer’s recommendations or flow research support different lengths


8.10 – Meter Performance• Meter factor shall be determined by proving the meter at stable operating conditions

i.e., essentially constant: flow rate, density, viscosity, temperature and pressure

•Chapter 4.8.2.1 “Operation of Proving Systems”


8.10 – Proving (cont’d)

• Questions often arise concerning the differences between proving or calibrating a meter in a laboratory (bench) versus in-situ (field)

• These two proving locations can produce different results and cannot necessarily be interchanged without introducing measurement error


8.10.2.1 – In-situ Proving• In-situ proving is normally preferred because it verifies themeter's accuracy under actual operating conditions

Operating conditions can affect a meter's accuracy andrepeatability

• In-situ proving at stable operating conditions compensates for variations in performance caused by flow rate, viscosity, density, temperature, pressure, as well as flow conditions, piping configurations and contaminants


Conclusion From API Field Tests1

• The batch volumes measured by the UFM’s agree very well with the batch volumes measured with the referee meters… the conclusion to be drawn is that the test meters and referee meters compare well so long as current meter factors obtained at operating conditions are used for each meter

• This simply reinforces the long held axiom that a custody transfer meter needs to be proved at conditions that are close to the conditions at which the meter will be used to measure custody transfer quantities

1. Ultrasonic Flow Meter Performance Evaluation of Field Test Data, Wesley G. Poynter, Ph.D., August 12, 2001


10.2.2 – Laboratory Proving• Laboratory proving is normally not preferredbecause laboratory conditions may not duplicate the operating conditions

• While there are more measurement uncertainties associated with laboratory proving, under certain conditions, it may provide the best alternative


11 – Proving Accuracy and Repeatability• Proving accuracy can be affected by the delayed manufactured flow pulses from a UFM

• These delayed manufactured flow pulses can lead to a bias error in the calculated meter factordepending upon the magnitude of the flow rate change that occurs during the proving run and the duration of the prove run


12.5 – Zeroing the Meter• Zeroing an UFM is a procedure that involves checking the output while the meter is blocked-in

• Under these conditions, and if the output of the meter does not indicate zero flow, then the manufacturer’s (re-) zeroing procedure shall be followed

• Whenever the meter is re-zeroed, it shall be re-proved


14 – Diagnostics• Certain parameters can be monitored based on the specific application. The parameters below are typical of those that may be accessed via a serial data interface or other means

• Comparing lab determined diagnostic parameters to the same parameters when installed in the field may help identify field installation effects or other parameter changes


Appendix B Verification and Validation of Meter Performance

• The turbulent flow field in a pipe is complex and contains numerous turbulent eddies and non-axial velocity components

• Turbine meters and other mechanical flow measurement devices integrate this field through mechanical convergence and are not particularly influenced by minor changes in flow stability


Meter Verification (cont’d)

• Ultrasonic flow meters take snapshots of the fluid velocity along one or more sample paths

• Real time integration of the flow field, including both axial and non-axial components, results in a less well-behaved output and inherently more scatter. However, this scatter, because it is random, will be evenly distributed around the mean meter factor


Meter Factor UncertaintyUFM performance verification can be ascertained byconventional means and to a level consistent withAPI MPMS, Ch. 4.8, Table A-1 which is:

±0.027% uncertainty at 95% confidence level


What Does This Mean?• Based on field data LUFM’s may require a larger

prover volume to achieve this same level of meter factor uncertainty

• More than 5 proving runs may be required to verify the meter’s performance


Appendix C Manufactured Flow Pulses and Their Impact on the Proving Process

Because the UFM uses an electronic sampling methodology to determine flow rate, the manufactured pulse train obtained from a UFM at any instant in time will represent flow (or volume throughput) that has already occurred (i.e., the manufactured flow pulses lag the measured flow).


Increased Sampling• In order to optimize the flow measurement, and accommodate unique installation effects, some UFM's can be configured to process a larger…number of measurement samples.

• Increasing the number of measurement samples…increases the time delay between the flow or volume represented by the manufactured flow pulses


Time Delay in Proving• In normal operation, delay between flow pulses and the actual measured flow has little impact on measurement accuracy if the correct meter factor has been used

• However, during the proving process, delayed flow pulses may cause poor run to run repeatability and/or introduce a bias error in the calculated meter factor


Flowrate vs K-FactorUltra6 10B - Groups Proving

30K Test System

988.000

990.000

992.000

994.000

996.000

998.000

1000.000

0 2000 4000 6000 8000 10000 12000 14000

Flowrate (BPH)

K-F

acto

r (P/

BB

L)

10B NO FC 10B HPFC

No FC:11.2:1 Turndown

Linearity = +/- 0.070%HPFC:

10.4:1 TurndownLinearity = +/- 0.062%

- Performance Data


Flowrate vs RepeatabilityUltra6 10B - Groups Proving

30K Test System

0

0.01

0.02

0.03

0.04

0.05

0.06

0 2000 4000 6000 8000 10000 12000 14000

Flowrate (BPH)

Gro

ups

Rep

eata

bilit

y (%

)

Repeatability Criterion 10B NO FC Repeatability Data 10B HPFC Repeatability Data

- Performance Data


Flowrate vs. K-FactorLUFM 8B - Ellerbek Testing July 2005

1000.00

1002.00

1004.00

1006.00

1008.00

1010.00

1012.00

1014.00

1016.00

1018.00

1020.00

0.0 1000.0 2000.0 3000.0 4000.0 5000.0 6000.0 7000.0 8000.0 9000.0

Flowrate (BPH)

K-F

acto

r (P/

BB

L)

8B with HPFC 8B with NO FC

Linearity:(11:1 Turndown)With HPFC: +/- 0.140%No FC: +/- 0.104%

- Performance Data


Flowrate vs. RepeatabilityLUFM 8B - Ellerbek Testing July 2005

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

0.160

0.180

0.0 1000.0 2000.0 3000.0 4000.0 5000.0 6000.0 7000.0 8000.0 9000.0

Flowrate (BPH)

Tota

l Rep

eata

bilit

y (%

)

8B w HPFC 8B Acceptance Criteria (HPFC) 8B w NO FC 8B Acceptance Criteria (NO FC)

- Performance Data


RecommendationsTo minimize any meter factor bias error, and/or to obtain the best possible span of repeatability results, it is important to ensure that:

The flow rate remains constant just before the first detector and throughout each prove run.

The time delay between the manufactured pulses and the actual measured flow is minimized in accordance with the manufacturer’s recommendations.

proa028i api review [לקריאה בלבד] - energy.org.il · api mpms chapter 5, section 8...

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