Transcript Fluke Template - Color

A Comparison of Primary Gas Flow
Standards Spanning the Range of
10 sccm N2 to 10 slm N2
Casey Rombouts
Flow Metrologist
Fluke Calibration
July 30 2014
2014 NCSLI Workshop & Symposium
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Introduction – Overview
For ease of reference, mass flow units will be referred to as
sccm referenced to 0°C and 101.325 kPa absolute:
2.1 x 10-2 g/s N2 = 1 L/min = 1000 sccm
• Participant/Authors in the Comparison
• Overview of the transfer standard artifacts
• Overview of each participants flow reference standards
• Results
• Conclusions
July 30 2014
2014 NCSLI Workshop & Symposium
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Participant/Authors
• Jean Barbe, Engineer
Laboratoire National de Métrologie et d'Essais (LNE) – France
• Casey Rombouts, Flow Metrologist
Fluke Calibration – Phoenix (FCP) – USA
• John D. Wright, Ph.D.
National Institute of Standards and Technology (NIST) – USA
• Rainer Kramer, Ph.D.
Physikalisch-Technische Bundesanstalt (PTB) – Germany
• Zdenek Krajicek, Ph.D.
Český metrologický institute (CMI) – Czech Replublic
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2014 NCSLI Workshop & Symposium
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Transfer Standard Artifacts
Certain commercial equipment, instruments, or materials are identified in this presentation to
foster understanding. Such identification does not imply recommendation or endorsement by
NIST, LNE, PTB, or CMI, nor does it imply that the materials or equipment identified are
necessarily the best available for the purpose.
• Three laminar flow elements (molbloc)
with full scale flows in N2 of 100, 1000,
and 10000 sccm, covered three decades
of flow
• Pressure, temperature, flow calculation
(molbox)
• Using the same molbox reduced uncertainties rather
than each participant using different instrumentation
• Uncertainty contributed by the transfer
standard stability is estimated to be
0.042 % of reading @ k = 2 (all data)
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2014 NCSLI Workshop & Symposium
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Flow Reference Standards – dGFS
• dGFS - used by FCP, LNE, CMI
• Mass flow from the fundamental SI
units of mass (m) and time (t)
• Mass, time and ambient condition
measurements, flow control and data
collection
• Catenary connection to minimize
unaccounted forces on the balance
• Continuous compensation for
buoyancy and comparator drift
• FCP uncertainty: 0.10 % of reading
• LNE uncertainty: 0.20 % to 0.06 % of
reading (down from 0.37 % to 0.09 %)
• CMI uncertainty: 0.10 % of reading
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2014 NCSLI Workshop & Symposium
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Flow Reference Standards – NIST
• PVTt - Pressure-Volume-Temperature-time reference
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Flow Reference Standards – NIST
P
PVTt vs RoR
RoR
PVTt
t
• PVTt - Pressure-Volume-Temperature-time reference
• Additional features result in an uncertainty of 0.025 % or better
• RoR - Rate of Rise method
• In the range of 10 sccm to 75 sccm, the uncertainty ranged from 0.08 % to
0.07 % of reading
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2014 NCSLI Workshop & Symposium
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Flow Reference Standards – NIST
• WGFS - Working Gas Flow Standard (not shown)
• Larger expanded uncertainty (0.1 % to 0.15 % of reading), but faster
The dGFS owned by NIST is used for research with no stated uncertainty. From 10 sccm to 100 sccm the
dGFS was used as a flow source through the artifacts to the PVTt / RoR allowing three primary flow methods
to be used simultaneously for the calibrations.
July 30 2014
2014 NCSLI Workshop & Symposium
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Flow Reference Standards – PTB
• Mercury Sealed Piston Prover
• Center tube (d = 44mm) used, 33 sccm to 1160 sccm range
• PTB uncertainty 0.25 % of reading
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2014 NCSLI Workshop & Symposium
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Flow Reference Standards – PTB
• Dual Piston Prover
• 0.08 sccm to 112 sccm
• PTB uncertainty 0.08 % of reading
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2014 NCSLI Workshop & Symposium
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Flow Reference Standards – CMI
• CMI dGFS Vacuum Bell Jar
• Theoretical uncertainty 0.02 %
• Practical uncertainty 0.04 %
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Results of the Comparison
Fluke (1)
NIST
LNE (1)
LNE (2)
PTB
CMI
Fluke (2)
Lab - Reference Value (%)
0.20
0.10
0.00
-0.10
-0.20
10
100
1000
10000
Flow (sccm)
• Reference Values calculated by the
methods of Cox
• Uncertainty weighted mean of
participants data
• Only one data set used from each lab
July 30 2014
• Reference Value uncertainties, RSS of:
• Participants stated uncertainty
• Standard deviation of the mean of
Participants data
• Transfer Standard Uncertainty
2014 NCSLI Workshop & Symposium
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Results of the Comparison
Fluke (1)
NIST
LNE (1)
LNE (2)
PTB
CMI
Fluke (2)
1.0
0.8
0.6
En
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
10
100
1000
Flow (sccm)
10000
• En - Standardized degrees of equivalence
𝑥𝑖 − 𝑥ref
• U(xref ) is subtracted from the U(xi )
𝐸𝑛 =
2
2
𝑈 𝑥𝑖 − 𝑈 𝑥ref
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2014 NCSLI Workshop & Symposium
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Conclusions
• All Deviations from the
reference value were < 0.1%
Lab - Reference Value (%)
• Error bars (Uncertainty) all
cross the zero axis
Fluke (1)
NIST
LNE (1)
LNE (2)
PTB
CMI
Fluke (2)
0.20
0.10
0.00
-0.10
-0.20
10
100
1000
10000
Flow (sccm)
• En values less than 1
Fluke (1)
NIST
LNE (1)
LNE (2)
PTB
CMI
Fluke (2)
1.0
0.8
0.6
0.4
En
• Results within a participants
stated uncertainty
• All values in this comparison
were 0.8 or less
0.2
0.0
-0.2
-0.4
-0.6
-0.8
• Nine reference standards, six
different methods
July 30 2014
-1.0
10
2014 NCSLI Workshop & Symposium
100
1000
Flow (sccm)
10000
14
Thank You
[email protected]
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2014 NCSLI Workshop & Symposium
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