calibration of pipe provers on location
TRANSCRIPT
Calibration of Pipe Provers in the field
Erik Smits, Senior Metrologist Liquid Flow & Volume at VSL
March 30th 2016
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Content
- Where and when are pipe provers used?
- Methods to calibrate pipe provers
- Measurement traceability (SI and/or USC)
- What uncertainty is achievable?
- Metering system accuracies and uncertainties
- Water draw method vs master meter method
- Some errors due to procedures
- Conclusions
Where and when are pipe provers
used?
- Initial (and re-) calibration and verification of
flow meters- At flow meter manufacturing site (calibration capabilities
preferred to be ISO/IEC17025 accredited)
- In flow calibration facility of a 3rd party. A National
Metrology Institute with CIPM MRA (e.g. VSL) , an
ISO/IEC17025 accredited company or a non accredited
company
- Field proving (calibration) of flow meters in a
metering system. Fixed and mobile units.
Calibration at real conditions
- Gravimetric method API MPMS 4.9.4 (2012)
- Water draw method API MPMS 4.9.2
- Master Meter method API MPMS 4.9.3
- Diameter and length measurements
What is an acceptable calibration method?
What are the advantage and disadvantage of
the different calibration methods?
Methods to calibrate pipe provers
Measurement traceability
SI measurement units or USC measurement units by conversion
- Water draw method API MPMS 4.9.20.02% to 0.05% in base (reference) volume
- Master Meter method API MPMS 4.9.30.03% to 0.07% in base (reference) volume
Measurement uncertainty for a pipe prover is not just the API range repeatability!
What uncertainty is requested for a metering system?
What uncertainty is achievable?
Metering system accuracies and
uncertainties (1)
Metering system accuracies and
uncertainties (2)
- Design (flow profile, upstream pipes etc..)
- Fluid properties (viscosity, density,
temperature, pressure etc..)
- Electrical connections (RTD, transmitters,
flow computer etc..)
- Calculations
- Use of standards (for example incorrect fluid
property data – made for general fluids)
- Etc…
Metering system accuracies and
uncertainties (3)
Meter Factor vs Pipe Prover API MPMS 12.2.3 section 12.3.1
Pipe Prover calibration uncertainty 0.02 0.05 0.07
Stability of Pipe Prover calibration 0.04 0.04 0.04
Flow meter calibration 0.05 0.05 0.05
Stability of flow meter 0.05 0.05 0.05
Design errors 0.02 0.02 0.02
Stability due to changing conditions 0.10 0.10 0.10
Other 0.07 0.07 0.07
Measurement uncertainty 0.149 0.156 0.164
Metering system accuracies and
uncertainties (4)
When the measurement uncertainty for the metering
system is large there is no need for a pipe prover
calibration with low measurement uncertainty
Not real measurement data!
Metering system accuracies and
uncertainties (5)
When the impact is small one can select the
calibration method that suits the location of the
pipe prover best. (provided that the service
company executing the calibration can perform
both methods!)
What are the advantages of the different
methods?
Water draw method:
- Method is described in API MPMS 4.9.2 (calculation in 12.2.4)
- Method with possibly the lowest measurement uncertainty
- Traceability direct to test measures (proving tanks) however, always at very low flow rate!
- Pipe prover needs to be cleaned before filling it with water
- A solid transfer point needed
- Only one pair of detectors per calibration run
Water draw method vs Master meter
method (1)
Water draw method vs Master meter
method (2)
Master meter method:
- Method is described in API MPMS 4.9.3 (calculation in 12.2.5)
- Traceability is indirect via a master meter. Directly before and after the calibration runs the master meter is calibrated with a master prover or proving tank
- The pipe prover does not need to be cleaned in when the liquid of the metering system can be used (big advantage)
- Calibration is done by counting pulses between detectors
- More pairs of detectors can be calibrated per run
- Repeatability requirements for runs, for calibration results of master meter before and after runs etc…
Water draw method vs Master meter
method (3)
Water draw method vs Master meter
method (4)
Water draw method vs Master meter
method (5)
- Stopping the sphere just behind the detector
will result in an incorrect temperature
measurement in the pipe prover
- Using grease on the sphere only to produce
smooth movement of the sphere through the
pipe. Not to fill up holes, scratches and other
defects on the sphere or the pipe wall
- Make sure the calibration unit is as close as
possible to the pipe prover. The connection
can cause all kinds of challenges
Some errors due to procedures
Conclusions
When the required measurement uncertainty of
the metering system is medium to high there is
no need for a pipe prover calibration with low
measurement uncertainty
In the field choose a calibration method that
meets your needs not of the needs of the
service provider
VSL
PO Box 654
2600 AR Delft
The Netherlands
T
F
E
I
Erik Smits
E
+31 15 269 15 00
+31 15 261 29 71
www.vsl.nl
Erik Smits:
http://lnkd.in/K3Hbya
VSL group:
http://lnkd.in/Bif3Sy
VSL Fluid Flow Metrology group:
http://lnkd.in/DF2zJx
@Erik_VSL
Questions ?