Liquid Meter Proving

Transcription

Liquid Meter Provers
2015 RMMS
Dave Seiler
Daniel Measurement & Control
What is Petroleum Fiscal Flow
Measurement?



When ownership of petroleum is
transferred from one company to
another, a financial transaction
occurs.
Accurate measurement of the
transferred petroleum is critical to
ensure an equitable exchange of
money for petroleum.
Flow measurement equipment serves
as the “cash register” for this
exchange.
Q=$
For custody transfer
flow measurement
equals dollars
[File Name or Event]
Emerson Confidential
27-Jun-01, Slide 2
RMMS 2015
Page 2
Custody Transfer - Accuracy Requirements
Government
W & M requirements
Legal limit
Customer’s desired accuracy
275.5
Manufacturer’s specification
275.0
274.5
Calibration data
274.0
273.5
}
273.0
272.5
272.0
271.5
271.0
270.5
0
20
40
60
80
% of Maximum Flow Rate
Maximum flow Rate = 11,400 Bbl/hr
27-Jun-01, Slide 3
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100
}
}
Flow Meter Types
Differential Pressure
- Orifice
- Pitot-staticTube
- Venturi
- Nozzle
Momentum
Force
- Turbine
- Target
- Positive Displacement
- Coriolis
- Swirl
- Elbow
- Wedge
- V-cone
Variable Area
- Rotameter
Thermal
Other
- Hot Wire Anemometer
- Electromagnetic
- Vortex Shedding
- Ultrasonic- Doppler
- Ultrasonic – Transit Time
Most commonly used
in Custody Transfer
Measurement
27-Jun-01, Slide 4
- Laser
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Custody Transfer Measurement

All custody transfer measurement are contractual and
usually cover…..
– measurement performance/accuracies
– frequency for measurement validation
– dispute resolution

Validation of measurement usually involves agreement
into the proving method which are tied to known industry
standards
– API, ISO, NIST …etc

Field (in-situ) proving most common
– establishes meter factor at working conditions
27-Jun-01, Slide 5
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Legal Approval and Standards
Organisation Internationale de Metrologie Legale (OIML)
– Organization of individual country weights and measures. Issues recommendation for
legal trade worldwide. Countries follow recommendations when establishing specific
regulations.
National Conference on Weights and Measures (NCWM)
– Organization of individual state weights and measures officials and National Institute of
Standards and Technology (NIST) technical advisors
– National Type Evaluation Program (NTEP)
– NIST Handbook 44
International Standards Organization (ISO)
–
Publishes technology specific standards
American Petroleum Institute (API)
–
Publishes technology specific standards for Oil and Gas Industry
27-Jun-01, Slide 6
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API – Industry Standards
Chapter 1
Chapter 4
Vocabulary
Proving System
Chapter 5 Sect 5
Fidelity and Security of flow measurement pulsed-data
transmission systems
Temperature Determination
Manual Sampling of Petroleum and Petroleum Products
Automatic Sampling of Petroleum and Petroleum Products
Chapter 7
Chapter 8 Sect 1
Chapter 8 Sect 2
Chapter 8 Sect 3
Chapter 9
Chapter 11
Chapter 12 Sect 2
Chapter 13
Chapter 14 Sect 6
Chapter 20 Sect 1
Chapter 21 Sect 2
27-Jun-01, Slide 7
Mixing and Handling of Liquid samples of Petroleum and
Petroleum Products
Density Determination
Physical Properties Data
Calculation of Petroleum Quantities using dynamic
measurement methods and Volume correction factors
Statistical Aspects of Measurement and Samplings
Continuous Density Measurement
Allocation Measurement
Electronic Liquid Volume Measurement Using PD and
Turbine Meters
RMMS 2015
Page 7
Meter Proving
What is a Meter Proving
–
Meter proving is the physical test used to determine the
accuracy and performance of a liquid meter
Why is Proving performed
–
The need for proving arises because operating
conditions differ significantly from the conditions under
which the meter is calibrated
Why Prove
–
–
–
–
27-Jun-01, Slide 8
Establish reference point under operating conditions
(initial installation)
Accounts for changes in meter accuracy
Verify repeatability / linearity of meter
Contractual requirement for custody transfer
RMMS 2015
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Why Prove: Uncertainty versus Yearly
Product Losses
Improvement in measurement accuracy of 0.10% on a 12,000 BPH (2,735 m3/h)
flow stream will result in product savings of $10,512,000 per year
27-Jun-01, Slide 9
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Meter Proving
How to Prove
– By placing a liquid meter in series with a meter
prover, which has a known or base volume in
such a way that all the liquid measured by the
meter is also measured by the prover
Meter
27-Jun-01, Slide 10
Prover
RMMS 2015
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Basic Proving Principle
 Regardless of the prover or meter type,
the same basic proving principle
applies
Known Volume
_______________
Indicated Volume
27-Jun-01, Slide 11
= Meter Factor
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When Proving. . . .
Proving Conditions Should Match the
Operating Conditions

Flow Rate

Temperature

Pressure

Liquid
Characteristics
Proving
Conditions
– API Gravity
– Viscosity
27-Jun-01, Slide 12
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Operating
Conditions
Measurement and Proving
S
P
T
P
D
Flowmeter
F
Coriolis Meter
Turbine Meter
API Chpt 5
covers Metering
Small Volume Prover
PD Meter
Liquid Ultrasonic Meter
Standards exist that outlines best practices for the
measurement technology as well as prover type
used
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API Chpt 4
covers Proving
Earliest of Provers
27-Jun-01, Slide 14
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Types of Provers Today
• Open Tank Prover
• Pipe Prover (Uni or Bi-Di)
• Small Volume Prover
• Master Meter Prover
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Types of Proving Systems

Pipe Provers
– Bi-directional
– Uni-directional
– Piston
– Reduced volume



Small Volume Provers
Master Meter Provers
Volumetric Provers
– Volume
– Mass
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Gravimetric Prover
Micro
Motion
27-Jun-01, Slide 17
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Four Basic Requirements
(1) Prove under normal conditions
The meter must be proved under the same conditions as it
is normally expected to operate.
(2) Adequate prover capacity
The meter prover must have a capacity large enough to
provide proving runs of adequate duration.
(3) Sufficient number of runs
A sufficient number of runs must be made to establish a
valid proving.
(4) Traceable results to National Institute of Standards and
Technology
Calibration of the meter prover must be traceable to
(NIST) calibrated test measures.
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Displacement Provers


Ball or Pipe Provers
27-Jun-01, Slide 19
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Meter Proving by Displacement
Pulses from Meter
Prover
Computer
START
STOP
Detectors
Flow from
Meter
Calibrated Volume
Displacer
Calibrated length
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Bi-Directional Prover
Pressure Gage and
Vent Connections
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Bi-Directional Prover
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Skid Package
Single U-bend
27-Jun-01, Slide 23
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Double Folded
Proving Provisions
Take-off / Block
Valves
Double Block &
Bleed Valve
27-Jun-01, Slide 24
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Conventional Pulse Counting
Discrimination
Stop Count
Start count
1
2
3
4
5
6
7
8
A
1
2
3
4
5
6
7
B
1
2
3
4
5
C
Actual 7.255 Pulses
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Page 25
6
7
8
Length Between Detectors

For Uncertainty ± 0.01%, at Least 10,000 Pulse
Should Be Collected During the Proving Pass

For Repeatability 0.02%, Calibrated Length Is
Dependent on Detector Switch Resolution (rd)
L
DT
rd
DT
rd
rd
L - 2rd
rd
L + 2rd
Max. Possible Difference in
Length for Round Trip is 4rd
For 0.02% Repeatability
(
L + 2rd
) -(
L = 4rd 0.0002
= 20,000rd
If rd = 1/32” Then L = 4 x 0.031 = 52 Ft.
.0002 x 12
27-Jun-01, Slide 26
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L + 2rd
)
= 4rd
Mechanical Detectors
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Length of Pre-Run (RP)
RP =
(
Tc-c
+
2
1
2
sec
) x Sphere Speed
Example:
Motor Operator Tc-c = 5.4 second
Sphere Speed = 4.97 fps
RP =
27-Jun-01, Slide 28
(
5.4
2
+
RMMS 2015
Page 28
1
2
)
x 4.97 = 15.9 ft.
Prover Volume


Pre-Run
Calibrated Volume to
allow 10,000 Pulses
Distance Between
Detectors
Prover Volume (30 ft)
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Displacer Velocity
Max. V = BPH x 0.286
(I.D.(in))2
5 fps for Bi-Di
10 fps for Uni-Di
Min. Velocity 0.5 fps
Example:
Max. Flow Rate = 2,500 BPH
Pipe Diameter = 12” (12” Sched. 40)
2,500 x 0.286
Max. V =
= 4.97 fps
2
(12)
27-Jun-01, Slide 30
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Uni-Directional Prover
27-Jun-01, Slide 31
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API Definition:

Old definition: A Small Volume Prover (SVP); is a
prover that will collect less than 10,000 meter pulses in
a prover pass.
27-Jun-01, Slide 32
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Small Volume Prover??
27-Jun-01, Slide 33
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API Definition:



Old definition: A Small Volume Prover (SVP); is a
prover that will collect less than 10,000 meter pulses in
a prover pass.
The new API Chapter 4.2 refers to a SVP as
“unidirectional piston pipe provers with external optical
switches.”
Reason: 10,000 pulse per pass is to generate the
mathematical precision necessary to calculate a four
decimal place meter factor accurately
27-Jun-01, Slide 34
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Compact Prover





Better than 1,000 : 1 Turndown
Small size / Light weight
Utilizes precision optical detectors
Pulse interpolation reduces pulse collection
Volumetric and/or Mass proving
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Size Comparison – ball vs. compact
27-Jun-01, Slide 36
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Small Volume Prover or Compact Prover
Pneumatic
27-Jun-01, Slide 37
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What Made Small volume provers
possible?

Precision optical volume detection switches

The double chronometry pulse interpolation
technique

The advent of modern computers and precision
timing techniques

Modern computers ability to average multiple
pass prover runs to statistically attain meter
pulses per run
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Mechanical vs. Optical Detectors
27-Jun-01, Slide 39
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Compact Prover Detector Switches
•A “flag” attached to a detector
shaft actuates switches by
interrupting a thin beam of light
•Switches are positioned by two
Invar rods which have an
extremely low coefficient of
thermal expansion
•Greatly Reduces effects of
temperature
changes on the volume
27-Jun-01, Slide 40
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Page 40
Materials of Construction

Flow Tube

– 17-4 ph stainless steel
– 304 stainless steel
– Carbon steel
Teflon Seals
Piston / Poppet Valve
 300 series sst
 Viton, Kalrez, or
Nitrile poppet valve
O ring
Rulon Rider Rings
Compatible with most hydrocarbon applications
27-Jun-01, Slide 41
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Main Piston Assembly
–
–
Internal poppet - designed so that flow is never stopped
soft o-ring seated to prevent product leakage and ensure
accurate calibration
–
Note dual piston rings with dual Rulon Ryders which wipe fhe
flow tube clean during piston retraction
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Proving Mode: Start Position
27-Jun-01, Slide 43
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Proving Mode: Start Pulse Collection
27-Jun-01, Slide 44
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Proving Mode: End of Pass (Stop Pulse
Collection)
27-Jun-01, Slide 45
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Conventional Pulse Counting
Discrimination
Stop Count
Start count
1
2
3
4
5
6
7
8
A
1
2
3
4
5
6
7
B
1
2
3
4
5
C
Actual 7.255 Pulses
27-Jun-01, Slide 46
RMMS 2015
Page 46
6
7
8
Pulse Interpolation

Definition
– Process of determining some value between two
known values through the use of a procedure or
algorithm.

Uncertainty requirement
– +/- 0.01% or 1 part in 10,000
• must be able to distinguish time to at least 0.00001 of a
second

Methodology
– Double Chronometry
27-Jun-01, Slide 47
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Double Chronometry

 A(Time)
C (Pulses)

K  


 D(Volume) B(TimeforPulses) 
K=Meter Factor
A=Time required to displace Volume D
B=Time required to accumulate whole flowmeter pulses, Count C
C=Whole flowmeter pulses counted during Time B
D=Calibrated volume of the prover flow tube between detectors
A
Interpolated meter pulses =
C
X
B
27-Jun-01, Slide 48
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Double Chronometry Example
A (TIME)
X
K=
D (VOLUME)
C (PULSES)
B (TIME FOR PULSES)
Time Counter 5 Mhz
A = Time for known displaced volume
in seconds
0 0 0 .5 8 3 7 7
Time Counter 5 Mhz
B = Time for whole meter pulses
0 0 0 .5 8 3 2 9
Pulse Counter (from meter)
C = Accumulated whole meter pulses
0 0 0 0 0 3 6 4
D = Known displace volume (by water
draw certificate)
0.58377
K=
0.35714 BBL
14.99988 Gal (.35714 Bbl)
364
X
1020.0468 pulses / bbl
0.58329
0.58377
Interpolated Meter Pulses = 364 X
27-Jun-01, Slide 49
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Interpolated Meter Pulses =
0.58329
364.2995
Setup Configuration for Calibration
27-Jun-01, Slide 51
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Waterdraw Diverter Valve System
27-Jun-01, Slide 52
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Calibration of Coriolis Meters
Prove like any volumetric flowmeter
Flow Direction
Prover
Computer
Block and Bleed Valve
Connection Valves
Test
Meter
Compact
Prover
27-Jun-01, Slide 53
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Prover Volume Conversion to Mass
Prover
Density determined from
densitometer
Flow Direction
T
P
27-Jun-01, Slide 54
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Page 54
Master Meter Proving
Flow Direction
27-Jun-01, Slide 55
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Transit Time Liquid USM – How it works?



Transducer locations placed for optimum measurement accuracy
Transducers act alternately as transmitter and receiver
Downstream pulses traverse stream more quickly than upstream
pulses
Q  Vaverage  A
where
Q = flow rate
Vaverage= mean velocity of the fluid in the pipe
A = area of the pipe
For multipath Liquid USM
n
Vaverage   wi vi
Multipath Liquid USM
27-Jun-01, Slide 56
1
RMMS 2015
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How do we Prove
Liquid Ultrasonic
Meters
27-Jun-01, Slide 57
RMMS 2015
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Earliest of Provers
27-Jun-01, Slide 58
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Proving Liquid Ultrasonic Meters
Differences exist in flow dynamics between
Turbine and Ultrasonic technology
 Turbine Meter
 Ultrasonic Meter
– Sees all of the flow
– Local turbulence is
averaged by the rotor
– The rotor can turn at only
one rate
– Little data scatter due to
inherent inertia of the
measurement element
– Uniform pulse train
27-Jun-01, Slide 59
RMMS 2015
Page 59
– Samples the flow at mutiple
chord locations
– Local turbulence is
averaged by many samples
– Short term repeatability is a
function of turbulence
– Data scatter due to ability to
measure minute variations
in velocity ie: turbulence
– Non-uniform pulse train
Proving Liquid Ultrasonic Meters

Coriolis and Liquid Ultrasonic Meters are
“manufactured pulse” type meters

There are two factors which can affect proving results.
– Proving accuracy can be affected by any delay in
pulses due to processing speed of the transmitter
– Ultrasonic meters produce a non-uniform pulse
output and has a varying frequency. This can cause
difficulty in obtaining acceptable repeatability while
proving

Proving run repeatability is used as an indication of
whether the proving results are valid

Proving run repeatability may not fall within the typical
5 run, 0.05% span of repeatability, however proving
runs shall repeat within the API Ch 4.8 guideline
27-Jun-01, Slide 60
RMMS 2015
Page 60
Uniform pulse output – Turbine meter
Frequency normally very constant
Non-uniform pulse output – Ultrasonic meter
Frequency variation due to ability to measure
minute variations in velocity
API Guideline to Proving Runs
Table B-1 – Proving an Ultrasonic Flow Meter

Repeatability = Counts – Low
((High Counts) /
API Chapter 5.8, Table
B-1 recognizes that an
increase in proving runs
may be needed in order
to achieve a ±0.027%
uncertainty of meter
factor
Low Counts) X 100
Runs
Repeatability *
Uncertainty
3
0.02%
+/- 0.027%
4
0.03%
+/- 0.027%
5
0.05%
+/- 0.027%
6
0.06%
+/- 0.027%
7
0.08%
+/- 0.027%
8
0.09%
+/- 0.027%
9
0.10%
+/- 0.027%
10
0.12%
+/- 0.027%
11
0.13%
+/- 0.027%
12
0.14%
+/- 0.027%
13
0.15%
+/- 0.027%
14
0.16%
+/- 0.027%
15
0.17%
+/- 0.027%
16
0.18%
+/- 0.027%
17
0.19%
+/- 0.027%
18
0.20%
+/- 0.027%
19
0.21%
+/- 0.027%
20
0.22%
+/- 0.027%
* per API MPMS Ch. 5.8, Table A-1 to achieve +/- 0.027%
uncertainty of meter factor.
27-Jun-01, Slide 61
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Page 61
Proving Volume is Important

The number of pulses
generated during a prove is
not the issue

The proving volume is
important in order to achieve
a successful prove on a LUSM

The critical issue is the
volume, not the prover

Use Master Meter – Prover
combination or a prover with
sufficient volume
27-Jun-01, Slide 62
From API Chapter 5.8 2005 edition
Removed from 2011 edition
Prover Volume vs. Meter Size
5 Runs
8 Runs 10 Runs
0.05%
0.09%
0.12%
Meter Size (in.)
Prover Size (bbl)
4
33
15
10
6
73
34
22
8
130
60
40
10
203
94
62
12
293
135
89
14
399
184
121
16
521
241
158
Table B-2 – Suggested Prover Volume to obtain
+/- 0.027% Uncertainty of Meter Factor
RMMS 2015
Page 62
RMMS 2015
Page 63
48” 600# Meter Prover for Crude Oil Service
27-Jun-01, Slide 63
Proving Manufactured Pulse Meters
Master Meter – Prover Method

In-situ prover – master meter combination is accepted and
recognized as a valid method to prove Liquid Ultrasonic
Meters
– Small volume Prover or Ball Prover used in combination
with a master meter
– Master Meter is calibrated against prover in-situ under
actual operating conditions



Master Meter proving is recognized by API and described in
the standard API MPMS Chapter 4.5
This methodology allows for longer proving cycle to improve
meter repeatability
Eliminates uncertainties due to laboratory calibration of
master meter on different fluids at different operating
conditions
27-Jun-01, Slide 64
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Page 64
Small Volume Prover Configured to
prove Coriolis or Ultrasonic Meters

Densitometer and Master
Turbine Meter
incorporated to prove
Ultrasonic and Coriolis
meters

Prover proves the master
meter which proves the
pipeline meters
27-Jun-01, Slide 65
RMMS 2015
Page 65
Master Meter Proving Using Small Volume
Prover

24” high temperature Small
Volume Prover configured to
prove Liquid Ultrasonic
Meters (6” to 10”) on crude oil
pipeline in Canada
27-Jun-01, Slide 66

RMMS 2015
Page 66
10” Multi-Viscosity Turbine
Meter as master meter
34” SVP w/master meter proving liquid USM
27-Jun-01, Slide 67
RMMS 2015
Page 67









Do not require 10,000 meter pulses per prover pass
Great fluid compatibility
Low pressure drop
Faster meter proving
Less product loss during proving operation, flush
from one product to another
Requires less space ( less real estate )
Lower transportation cost for portable provers
Field Replaceable volume switches
High accuracy waterdraw calibration
27-Jun-01, Slide 68
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Page 68
In Situ Proving – Cryogenic Prover






Concepts evolved from bidirectional piston provers
Free floating piston
Honed prover barrel
Piston prover well established
and commonly used on liquids
operating at -45 DC
Meet API repeatability criteria
Special design details applied
for LNG for operation at
approximately -260⁰F (-162 ⁰C)
27-Jun-01, Slide 69
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Fully insulated for LNG Service
27-Jun-01, Slide 70
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Summary

Although Displacement Provers operate on the
same basic concept, a prover is a complex piece
of equipment and may have widely differing
arrangement and operating features.

Each application for a prover should be studied
carefully so that optimum choices can be made
for equipment, installation and operation
Proving methodolgy must be carefully
considered and agreed upon by all parties when
using Manufactured Pulse type meters.

27-Jun-01, Slide 71
RMMS 2015
Page 71
Liquid Meter Provers
2015 RMMS
Dave Seiler
Daniel Measurement & Control

Liquid Meter Proving

Transcription

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