Metering for Custody Transfer and Royalty Computations

METERING FOR CUSTODY TR!NSFER

AND ROYALTY COMPUTATIONS

by

R. E. CLAUSEN

ARABIAN AMERICAN OIL COMPANY

DHAHRAN, SAUDI ARABIA

MARCH 1961

(Revised May 1961)

77

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METERING FOR CUSTODY TRANSFER AND ROYALTY COMPUTATIONS

The oil industry has been interested for many years in the use

of meters for custody transfer and royalty computations rather than by the

generally accepted practice of hand gaging of tanks. The reasons for the

interest are; the savings of expendi'liures for installation of tankage,

which in turn reduces evaporation losses; provides for more flexible and

efficient operations, resulting from increased use of facilities such as

tankage, pipelines and ship loading facilities by reducing waiting time

necessary for manually taking opening and clOSing gages; labor savings

in those cases where metering can be made automatic and unattended.

Another reason is the possibility that metering is more acaurate than

-manual tank gaging, which benefits both parties where royalties are

involved •.

Prior to 1942, research on the accuracy of positive dis-

placement meters was done by the American Society of Mechanical Engineers.

Since then, guidance of research has been a joint venture by ASME and

American Petroleum Institute committees. Standard methods were developed

for design, research, testing and operation of meter measurement of liquid

petroleum hydrocarbons by positive displacement meters. These methods

were included in ASIvlE publications, National Bureau of Standards Handbooks,

the API Standard 1101 and other publications. Because of the need, about

the year 1956, high capacity turbin!3 type meters were developed and larger

positive displacement meters were built. It is understood 'that because

of the increasing use of turbine Illeters which are becoming more accurate,

the API is changing the name of their "liquid positive displacement

committee tl to "liquid measuremen'~ committee."

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DEFINITION OF TEIUAS USED FOR METERING

It may be well in our discussions of metering to give a

brief definition of terms used:

Meter - An instrument for measuring, usually for recording automat

ically the quantity measured.

Positive Displacement Meter - As shown in Exhibit 1, this is a device

installed in a piping system in which a flowing liquid is mechanically

isolated into segments of known volumes. These segments of liquid are

counted as they are displaced and their accumulated total are conti

nuously indicated in units of liquid quantity by the meter register in

gallons, barrels, tons, etc. In other words liquid is measured by volume

of displacement. This is done in several ways such as rotary vanes,

buckets, lobes, or helical rotor or o~cillating and reciprocating piston

or any combination of these.

Turbine-Type Meter - As shown on Exhibit 2 and 2a

this is a device that measures flow by velocity and utilizes a turbine

which turns with the passage of the liquid and registers units of measure

ment on a totalizer> t:...i. ther mechanioally or by eleotrical impl.lses induoed

from magnets on a shaft, or on the turbine blades.

Prover - A prover is a device for calibrating meters. This can be

an open or closed vessel, tank, a section of pipeline, or container

that is accurately measured. The prover can be either gravametric by

weighing the liquid or volumetric which accurately measures the volume.

Exhibit 3 shows a Seraphin tank type and Exhibit 4 a calibrated pipe

p~s~on type prover.

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Master Meter Prover - This is a meter whioh has been tested for

aoouracy by a prover of volumetric or gravametrio type.

The master meter prover is then used as a prover to cheok

and calibrate other meters in flowing liquid measurement

servioe.

Meter Accuracy - This is the per oent of volume, more or less,

measured by the meter as oompared to a prover or gaged

tank. Although standards of acouracy have not bee~

established an arbitrary ori teria is to have meter

accuracy within 1/4 of 1 peroent.

Meter Factor or Calibration Factor - This is a number whioh is

the ratio of actual quantity of liquid in a gaged tank· or .

prover as oompared to the ~tity shown on the meter

I'egister. It is obtained by dividing by quantity measured

in. the prover or gage tank by the meter l·sgistration and

is usually a number suoh as .9985 to 1.0015. In order to

get the actual liquid throughput, the IlUIllbers on the

meter registration are multiplied by the metel' fac·tor.

Repeatabilit:[ - Ability of a. meter to repeat reGi~tertition at a.

given flow with sustained aocuracy. This shows up by

oomparing the meter factors i.l.'om several runs of a meter during

operations is oompared to ga.ged~c;<.;:tks or prover systems.

Se~:':.'l:r~~.~n Tapk Prover - A tank with a gradi:Ul;!;ed neok of reduoed

or()m~ PJ~cf:! ')"1. h allow for more aocurate determination of

incremental volume.

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Temp!rature Compensator - A meohanism whioh automatioally ohanges

the meter registra-tion in response to temperature changes and

resulting volume ohanges in the flowing streams. This makes

it p?ssible for the register to read direotly in barrels or

tons at 60 deg. F.

Vi~cosity dompensator w This is a devioe automatioally oompensating

and adjusting registration for the effect of any changes o~

viscosity of the flowing liquid on the meter aoouraoy. An::!

signifioant o~s in visoosity have a pronounced effect on

the meter factor and accuracy.

OIL nmuSTRY EXPERIENCE WITH i,;;~TER]1f(j.

The oil industry experience wi,th metering for automatic oustody

transfer has generally been good. Positive displacement meters for royalty

have been used in southern USA. by many oil oompanies as far back as 1942.

Humble Pipe Line Co. in 1957 had run 100 million barrels of oil on,

automatio oustody transfer with oomplete satisfaction. There are m~

inst.allations for metering crude in the USA where data have been oolleoted

to assure acoeptable acoura.oy. However most of this metering was done

prior to 1956 with meters no larger than 2,800 barrels per hour. Sinoe_

there was a demand for higher oapaoity meters, two meter ma.nufa.oturers,

undertook to design and build meters of approximately 10,000 BPH. The

. test work was oarried out by Esso Researoh with four pipeline oompanies.

One meter wa.s of the turbine type with a oapacity of 15,000 BPH and the

other a positive displacement meter of 10,000 BPH which was later

,increased to 12,500 BPH. Results indicated an acouracy

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within .05% for the positive displacement meters by the prover tank

methods. Further developmen~ was done by the manufacturer on the turbine

t~ meter to provide for viscosity compensation and the results have

been encouraging.

Data from some oil companies indicate that on various metering

installations the acauracy of meters compared to statio tank gages has

ranged from .04% to 0.20%. Generally it was conoluded that orude metering

is as accurate as tank gaging.

ARAMCO EXPERJENCE WITH MIl1TERDfG

hamoo has tested positive displaoement meters of 2,500 BPH

oapaci ty in various services principally bunker fuel. Aramoo has also

tested turbine meters from two manufacturers, with and without visoosity

. compensation. Three sizes of turbine type meters without viscosity

compensation were used, a 2t"-600 BPH, a 6"-4,000 BPH capacity, and a

l2n·l7,OOO BPH capacity. ·There are two sizes of the turbine meter, with

viscosity compensation one 16" 15,000 BPH capacity, and a smaller 10" -

7.000 BPH capacity.

Sinoe ~", 6" and 12" meters were not visoosi ty or temperatUre

o ompensated, it was necessary to manually adjust the eleotronic totalizer

for temperature and viscosity by use of a meter or calibration fe.otor.

The 16" meter which inoorpora)ed both visoosity and temperature

oompensation integrated with the register to read out net barrels at

600, without bottom settings and water oorreotion.

Positive Displacement Meters - 8"-2,500 BPH

Twelve 2,500 BPH positive displacement me~ers are installed in

bunker fuel service on both the North and. South Piers at Ras Ta.:rmra.

Terminal. In addition there is one master and. OllS spare meter.

These meters are

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periodically calio .... rr.-t;ed with a master meter which is in ·mrn checked

at a volumetrio proving station using a 100 barrel seraphin neok proving.

tank.

As shown on the ohart in Exhibit 5, the accuracy of these

positive displaoement'meters in bunker fuel service is held within !O.2~

oompared to tank gages. Testing the PD meter in various servioes to

determine the effects of changes in loading rate and viscosity showed

an accuracy of t 0.25% at flow rates of 25 to 100% of the meter design

oapacity regardless of oil temperature and product tested. These positive

displacement meters have a built-in temperature compensator whioh Aramoo

fm~ necessary to preoisely reoalibrate for the flow oonditions to avoid

possibility of error. In general this positive displaoement meter was

more accurate for. the higher visoosity fuel oils which was +.05 to -.25%

as oompared to +.18 to -.;0% for the lower visoosity diesel oils based

on prover tank.

Positive Displacement - 4"-150 BPH

A positive displacement 4"-750 BPH capacity meter was installed

in Ain Dar GOSP-2 between the test trap and spheroid. The meter operated

~tisfaotory with an acouracy of better than 1.0% but had a limited life .

. due to over-speeding and oil and gas two-phase flow conditions.

Turbine Meters - Turbine-Tw

The 2t" turbine type meter without visoosi ty oompensation was

installed in Abqaiq Gas Oil Separating Plant No.2 in a line from a high pressure

test trap to a spheroid. This was for the purpose of determining well gas oil

ratio. The meter was not satisfaotory because of two-phase flow oonditions.

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The 6""4,000 BPI! meter without temperature or viscosity compensa

tion was installed in the Ras Tanura Terminal proving station. As shown

by the oharts, Exhibit 6, the meter wa~ tested with bunker fuels. The

accuracy with the relatively low viscosity black diesel oil (48 SSU or 6

centistokes) was t 0.25%. In heavier fuel oils the accuracy: varied as

muoh as .± 0.95% which is not acoeptable. Later this meter was relocated

to a gasoline line and. showed an accuracy of +.06 to -.6~ oompared to tank

gages. However the tank gages between the refinery and terminal varied as

muoh as 0.59%. The average meter faotor considering the plus and m.inu.s

factors for individual runs balancing out was .9999 or accuraoy of .01%

whioh was muoh better than the tank: gages.

The 12" 17,000 BPI! turbine meter without visoosity oompensation

was installed at Ras Ta.rDlra Terminal in a. by-pass off of a 22" ship loading

line. As shown by the chart, Exhibit 7, the oomparison was within ± 0.2~

of tank gaging with Arab· Zone orude of 5. to 10 centistokes 34 API from

80 to 115 deg. F. When testillg in the higher visoosity Safaniya c7Ude

(average 48 oentistOkes) the oomparison with tank gages was t l.25%.

On this basis the turbine type meter without a. visoosity oompensator is

not su.ffioiently accurate. The manu.faoturer has redesigned and built a

12" meter whioh will allow for viscosity variations. This will be tested - .

upon arrival in Saudi Arabia.

Turbine ~ Meter with Visoosity and Temperature Compensation

A 16"-15,000 BPH turbine-type meter of different ma.nufa.oturer,

with viscosity and temperature compensation was installed in the same bypass

off of the 22ft ship loading line used for the 12"-17,000 BPI! meter test. r.i~ S)'~ . ~ 4....1 f.l\.';:{irr"·¥'/v ry n.,;. -;;;;;,- ?{\;:;r;;:, J- 1Jt ~ '/~~",-' ~"""·,,,-",~(,,.1 As can be seen by tHe ohart , Exhibit 8, the comparison of the metering with

the gages w~s very favorable for both the lighter visoosity Arab Zone based , .

on six ship loadings and heavier Safa.:niya. Z.one orudes based on 14 ship

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loadings with temperatures ranging from 70 to 90 deg. F. The oomparison was

t 0.31% for Safaniya and ! 0.13% for Arab Zone. The ± 0.31% aoouracy for

Safaniya orude included all runs. The aoouraoy was: 0.24% when ~estion-

able runs were deleted. However the meter faotor averaged .9974 or an

acouracy of 0.18% with a total run for Safaniya orude in exoess of one

million barrels. The results of the several runs showed very good repeat

ability of .0028 from mean average. The meter factor varied from below unity

for Safaniya orude ~o above unity for both Arab Zone orude and gasoline indi

oating that a different ad~stment meter faotor should be made to the meter

for various visoosities. During these test runs the mioro adjustment was not

ohanged on the meter.; The meter factors obtained from meter register and tank

gages was very olose to the meter faotor oalibrated by the ma.nu£acturer at

their testing station in the USA. It is possible after the test runs to o~

the mioro adjustment suoh that the meter faotor for speoifio orudes will olosely

approach unity as oompared to t a.nk gages. If this meter faotor had been adjusted

to be unity the meter would have registered 22 barrels more than the tank ga.(!}aS

for a ,total for 14 runs of a million barrels oonsidering the plus and minus

factors offsetting each other for the ,individual loadings.

The tests on this 16" visoosity oompensated meter have not been

oompletely evaluated at this time. With oontinuing tests we will ha.ve more

data as to the assured acouraoy. At the beginning of the tests oonsiderable

trouble was encountered with a small ,gear assembly whioh aotuated the meohanioal

read out meohanism. The manufaoturer has oorreoted this diffioultyand we

have not experienced any further diffioul ty during a total throughpllt to

Maroh 25 of 1,720,000 barrels inoluding 1,056,000 barrels Safaniya and

664,000 barrels Arab Zone orude.

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Maintenance

The test on the turbine type meters have not been of sufficient

duration to determine what maintenance difficulties can be expected.

In the case of positive displacement meters Aramoo has found these

meters to have a relatively short life in oil and gas two-phase flow service

owing to overspeeding and shock. In bunker fuel service the positive dis-

placement meters initially had problems with the plastic gears for the

read out register. This was corrected and no further difficulties have been

experienced so far. However these meters have not been in service long

enough to evaluate the maintenance problems.

Effect of Viscosity on Meter Calibration

As shown on Exhibits 9 and 10 the viscosity of the fluid being

metered has 90nsiderable effect on the calibration for both the positive

displacement and turbine meters. The manufacturer of the 16" turbine type

meter has developed a viscosity oompensator which is a great improvement.

A turbine meter to take care of viscosity variations is now being developed

by another manufacturer.

Comparison of Positive Displacement and Turbine ~eters

Exhibit 11 shows the comparison of positive displacement and

turbine meters. For purposes of illus·tration a 12,500 BPH positive displace

ment meter is compared with a 16"-15,000 BPH turbine type meter. You will

note that the positive displacement meter is much larger and weighs six times

as much. It is necessary to build the large oases for positive displacement

meters to keep the pressure drop down. The positive displacement meter has the

big advantage of having demonstrated good accuracy over the past several

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However it has only been in recent years that large capacity positive

displaceme~t meters have been built. Before 1956 it was necessary to·

use batteries of several positive displacement meters to obtain greater

capacity.

Positive displacement meters are manufactured in sizes from 24

to 8,750 gallons a minute or up to 12,500 barrels per hour. However,

we have recent advice that a 20" and 24" meter has been developed. These

have a capacity of 20,000 to 25,000 barrels per hour.

EXhibit 12 is a photograph that dramatically shows the rela

tively smaller size of a one 6" turbine meter replacing a battery of eight

positive displacement meters. Exhibit 13 indicates a direct comparison of

the same capacity turbine and positive displacement meters, both 10,000 BPH.

The main a.q.vanta.ge of the turbine meter is the small size and weight, lower

cost and fewer moving parts.

Turbine Type Meters

It is understood that there ·are as many as ten or twelve

ma.nu.f'acturers of turbine type meters. As mentioned above the turbine

type meter is basically a velocity meter whereas the positive displace

ment meter measares volume.

The original turbine type meter tested by Aramco did not

have viscosity or temperature com~nsators, therefore it was necessary to

correct the registered ~antities by ~anual means considering the gravity

and temperature at flowing conditions. However, .the manufacturer is now

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developing a J'!leter which will correct for viscosity changes. A 1211 size

will be tested by Aramco in the near future.

The 1611 - 15,000 BPH turbine meter tested by Aramco has a viscosity

and temperature compensator built-in. It has a mechanical register which

shows the net barrels after correction and two connections for read out on

electric registers, one for gross and the other for net barrels at 60 deg. F

without correction. for BS&W. The electrical connections make it possible

to have registers at remote control rooms or offices and the mechanical

register has the advantage ,of continued meter readings in case of a power

failure.

Meter Ldfe Expectancy

Ldfe expectancy of meters is dependent upon use at the maximum

and minimum rates. A general formula for positive displacement indicates

a life of 25,000 hours at minimum rate and 5,000 hours at maximum rate.

For a life expectancy in barrels for a meter with a 3,000 to 15,000 BPH

it would be expected to last for 75,000,000 barrels at maximum capacity.

Turbine meter manufacturers claim a three times longer life for their

meters. One turbine meter manufacturer indicated his 15,000 BPH meter

could last as long as one billion barrels or 66,000 hours. This might

be very optimistic since our recent test indicated the meter was used an

average cf 220 hours per month which would make the meter life 25 years.

At this rate of use a positive displacement meter would last from two

years at maximum rate to 10 years at minimum rate.

METER ACCURACY REQUIRED

Since past history with custody transfer and royalty has been

tank gaging, it follows that meter accuracJ'~uld be comparable. It is

our understanding that no standard has been established to date for meter

aocuraoy. As a guide Aramco has arbitrarily considered that accuracies

of meters should be + .25% as oompared to gage tanks and + .15% for - -

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The guide for ~ethods of proving meter accuracies is oontained

in API Standard 1101. Meter accuracy is dependable where properly and

frequently calibrated against provers for each grade of oil. Meters

have been tested against tank gages and found to be just as accurate and

in some cases may be more accurate than manual tank gaging.

Factors that Affeot Accuracy in a Meter

Temperature Variations - An error of one degree in the readillg

of thermometer oa.n make a difference of .05% whioh is a large part of

0.25% normal accuracy limitation.

Visoosity - Viscosity ohanges from Arab Zone crude from six

oentistokes to 48 centistokes for' S8.fa.niya Zone crude oa.n make a

difference of ± .15% in accuracy unless automatically compensated or

manually oorrected.

Two-Phase Flow - There cannot, be 81lY free gas in orude oil

when metering.

Meohanioal Drag - For either P.D. or turbine meters with

meohanioal registers, ticket printers, eto. 81lY excessive meohanioal

drag oan oause slippage and affect the. acouracy.

Factors that Affeot Acouracy in Tank Ga.g;i.ng

The inacouraoies in metering that might result from these

faotors can be off-set by oertain inacouraoies in tank gaging, suoh aSI

(1) Errors in taking temperatures whioh is the same as for metering.

(2) Use of the ASTM-IP tables for oorreoting to 60or. These tables

were prepared from averages of various orudes, therefore a

partioular orude being gaged oould be inaoourate.

(3) Encrustation on inside wall of tanks.

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(4) Errors from tank bottom flexture.

(5) Tolerance in gaging to the nearest ± 1/8" or a total of 1/4" for

opening and closing gages. As an example, for the tests with

the 16"-15,000 BPH turbine meter, the average loading was 75,000 bbls

and the 1/4" amounts to 78 bbls or an error of 0.10%.

(6) Changes in thickness of BS&W under the gage hatch.

(7) Tolerances for strapping the circumference of tanks plus errors due

to temperature differences in the steel during the strapping.

(8) Tolerance in measuring dead wood.

(9) Variation of the tank shell due to out of roundness.

METERING FOR CUSTODY TRANSFER AND ROYALTY COMPUUTIONS

Customer and Government Acceptance

We wish to acknowledge and thank the representatives of the

Saudi Government Petroleum 1tinistry for their interest and assistance

during the meter studies over the past ,two years. They have encouraged

us and have been very helpful on the meter testing. In fact, their

engineers have assisted in the actual work and evaluation of the results

for some of the tests.

We anticipate that Aramco people Viill continue to work closely

with the Petroleum }tlnistry on meter studies and test work until it is

finally resolved and assured that meters are sufficiently accurate and

reliable for custody transfer and royalty computations.

The Petroleum 1timstry has agreed since May 1960 to aocept positive

displacement metering with a prover tank installation for Safaniya on shore

wellE which for three wells up to the end of May 1961, has amounted to

approximately 3,950,000 barrels estimated value about $5,500,000.

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Agreement has also been reached on metering crude to tank cars for a

customer, which over six months December 1959 thru Ma.y 1961 amounts

to an estimated 96,000 barrels valued at about $170,000. In addition,

since July 1959 through end of May 1961 the customers have aocepted

positive displacement meter tickets for about 24 million barrels of

various kinds of bunker fuel, estimated value $41,000,000. A battery

of three 3,000 BPH positive displacement meters has been installed for

trial purposes in the Arabia-Bahrain pipeline. The runs are being checked

by a fourth meter used as a master meter calibrated by a prover tank and

by tank gages. In addition,for test purposes a 10" - 7,000 BPH viscosity

and temperature corrected turbine type meter is installed in series with

the positi~e displacement meters. We will have the results later in the

year.

In conclusion it appears that with the encouraging results so

far,there is a good possibility that agreement can be reached and larger

meter installations be installed, based on the justification from savings

in tankage and manpower plus the inoreased effioiency for pipeline deliveries,

pier operations and tanker loading.

REC:maz 3/25/61

Revised: 5/31/61

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Exhibit 1

2

~a

3

4

5

6

7

8

APPENDIX

Photograph of a Positive Displacement ~leter

Photograph of a Turbine Type Meter (cut away)

Photograph of a Turbine Type Meter

Photograph of a Prover Tank (Seraphin)

Photograph of a Pipe and Piston Type Prover

Chart showing Positive Displacement Meter Accuracies with Bunker Fuel Oil

Chart showing 6" Turbine Meter Accuracies Bunker Fuel and,Gasoline

Chart showing 12" .Turbine Meter Accuracies Crude Oil

Chart showing 1611 Turbine Meter Accuracies Crude Oil

Photograph of 16" - 15,000 BPH Turbine Type Test Meter Installation

9 Chart showing Effect Viscosity Positive Displacement Meter

10 Chart showing Effect Viscosity Turbine Meter

11 Tabulation - Comparison Positive Displacement and Turbine Meters

12 Photograph - Comparison One Turbine Meter with Battery of Positive Displacement Meters required for same capacity

13 Photograph - Comparison Turbine and Po~ltive Displacement Meters - Same capaCity

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(A'!

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The ROCKWELL

UPSTREAM DIFFUSER SECTION

VISCOSITY MECHANICAl COMPENSATOR COUPLING

ROTOR ELEMENT

TYPE IS M

MAGNETIC COUPLING

DOWNSTREAM DIFFUSER SECTION

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11

I 'F'

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/NORMALLY OPEN MOMENTARY CONTACT SWIT/,S

.~ ~DETECTOR SWITCHES 1ti 1 ...... ---

. - .... ___ CALIBRATED PIPE

0 I -I IXZ XI -c: l ' I· -, -PLUG ..... ..J

1 1 'H '±p t ~T - ~ J. ---+ F G I I EAST RUN __ - - 0 f _WEST RUN .;A ..... ..

l I fi PULSE GENERATING I TACHOMETER •

~ :I.e ~ "'e I

--1.01 ~

iIo

L - OIL FLOW ((» A 'OPERATING SYSTEM

METER

I I I ELECTRONIC RELAY I I

SUPPLY VOLTAGE

115 V 60'\., AC , I ELECTRONIC COUNTER

N MAINTENANCE MECHANICAL CORP.

HOUSTON. TEXAS.

wtE SCHEMATIC· DIAGRAM OF CALIBRATED PIPE

S . METER PROVING SYSTEM DATa SCALa DRWG. NO.

, REV. DIIecR.I"T.ON .v DATE

DftN. CHK •• APOR. Bulletin P-I04, Fig.1 ~

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+.3

8 INCH POSITIVE DISPLACEMENT METER

COMPARISON OF METER REGISTRATION

TO

PROVER TANK TANK GAUGIN G

+.2 BLACK DIESEL ..".,.,.,""'" + . I 8 %

..,..,..,.,.,..,. + . 20 %

+ .1

01---1::

- .1

--2

--3 ~",,_·3 %

FUEL OIL FUELOIL A-951 +.05% A-933+. 04 % I

~oua-.20%

AVERAGE METER

REGISTRATION

IiELD WITHIN

+. · 20%

~~----------------------------------------------------~

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+.6 +.4 +.2

+1.0 +.8

Z +.6

6 INCH TURBINE METER (NOT VISCOSITY COMPENSATED)

COMPARISON OF METER REGISTRATION TO PROVER TANK

BLACK DIESEL

I 'FUEL OIL COMPARISON OF FUEL OIL A-933 METER REGISTRATION

A-95r +-95% TO ,TANK GAUG IN'G +.8% .

Q +.4 L- 2 FUEL OIL GASO LIN E ~ +. A-933 ...... +-06%

O~·--------------------~----~~-------~::~~-------~~~---------------~~-----,~ ;".:.2 .FUEL OIL > A-951 _.4

~ -.6 _ .8

-1.0 _.2 __ 4

-.6 -.8

--2.0

ACTUAL METER REGISTRAT. ON

1 .1 METER FACTOR CORRE. CTED

BY MANUAL ADJUSTMENT

FOR EACH TYPE OF PRODUCT

_.60%

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-..J

.4

.2 +1.0 +.8 +.6 ..... 4 +.2

12 INCH TURBINE TYPE METER (NOT VISCOSITY COMPENSATED)

COMPARISON OF METER REGISTRATION TO TANK GAUGING

I SAFANIYA CRUDE.

SAFANIYA CRUDE ARAB ZONE

CRUDE +·2%

~r:::R + 1.25 %

z o .() t-------~ ~. t-· <I: -.4 a::: -.6 ~ -.8

-laO o-e -.2

-.4 -.6 _.,8 ...

-2.0 _.2 _.4

ARAB ZONE CRUDE

ACTUAL METER REGISTATION I

_1.25 ~

METER FACTOR CORRECTED

BY MANUAL ADJUSTMENT

FOR EACH TYPE OF CRUD·E ..

~------------------------------------------------------~

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+.4

+ .3

+ .2

+ .1

z, o -.1 ~ =-.2 ~ --.3

-- .5

-- .6

16 INCH TURBINE· TYPE METER VISCOSITY. COMPENSATED

COMPARISON OF METER REGISTRATION

ARAB ZONE TO TANK GAUGING

CRUDE

I SAFANIYA CRUDE I

ACTUAL METER REGIST RAT JON

SAFANIYA CRUDE

ARAB ZONE CRUDE ~~. +0.13%

-O.I~ ~t

.....

+0.31 %

-0.3"%

METER FACTOR CORRECTED

BY MICRO ADJUSTMENT

FOR EACH TYPE OF CRUDE

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VISCOSITY--ACCURACY RELATIONSHIP

A sealing film of SAE-40 lube oil will withstand more pressure than a film of gasoline. This being true, it can then be stated that: "under constant conditions of clearance and prt:ssure loss, the movement of liquid, through the clearance around the displacement members, will decrease as viscosity increases. II See curve "D".

The slope of the accuracy curve will also change with changes in viscosity-the higher the viscosity the flatter the accuracy curve.

It is therefore evident that for close accuracy, a meter should be tested and adjusted with the product it is to measure in service and at about the same rate of flow. The graph should not be used as a basis for adjustment in lieu of a physical test. It serves only as a guide.

0.7Q~ ,

-f-0.60~ Each apace equals 1- approximately 0.50~ one-tenth of one percent -I-0.40~ 0.30~

0.20~ 0.10 ~ ~ 0 ~

30 35 VISCOSITY

I..,......--' ~

~ .....

~

40 50 60 80 100 S.S.U.

POSITIVE DISPLACEMENT METER ACCURACY CURW

150

-

EXHIBIT 9

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1.67

1.66 EXPERIMENTAL RESULTS APPROX. VISCOSITY

1.65 SYMBOL (SSU.)

0 250

1.64 A 100

l~b3

'--' Z -'" 1.62 (/)

Z «

I 0 Z50

kCURVE 3 X '100

~( I I ~ .

~. w CURVE 2· ~

~~ A. I" A

a « 1.61

.. 1r-fJ -- 't X -x -0

~

'" 0 1.60 ~C~RVE ) J i

><

310 f 1.59

c K-CURVE I

'-.

1.58 o

: LAMINAR7 REGION

I 5

~f·

I REYNOLDS 10 IS 20 25 30

\::,. TRANSITION REGION

CRITICAL ZONE

NUMBER (R.) 35 40

VISCOSITY

COMPENSATOR

NO

NO

YES

YES

LU x-x':"" -...

JC 10-' 4S SO 55 60.

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Capaoity

Cost (approx.)

Weight

Size

Head Loss

40 SSU

200 SSU

Advantages

Disadvantages

COMPARISON -POSITIVE DISPLACEME1"TT & TURBINE I.illTERS

PD

12,500 EPH

$25,000

5,800 1bs

56" high x 46" long

Turbine

15,000 EPH

$10,000

1,000 1bs

23-~" dia.f1ange x 42" long

3.2 psi solvent 400API 2.0 psi

3.2 psi

More experienoe - acoepted Low cost as accurate

Less slip with high viscosity oils

Greater drive to operate aooessories

Does not require long straight runs of pipe or straightening vanes.

High cost

Large size and weight

Many moving part s

Cannot be over-speeded

Must have fil tars for grit and dirt.

Small size and weight

High capaoity

Few moving parts

Passes soa1e, dirt easily

Can build in viscosity correction.

Relatively new - have Ie ss experienoe

Viscosity changes have pronounce:l effect unle ss automatic correction device provided

Low driving foroe to drive accessories.

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Metering for Custody Transfer and Royalty Computations

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Transcript of Metering for Custody Transfer and Royalty Computations