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NBS TECHNICAL NOTE 943

CE / National Bureau of Standards
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards 1 was established by an act of Congress March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and

technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to pro- mote public safety. The Bureau consists of the Institute for Basic Standards, the Institute for Materials Research, the Institute for Applied Technology, the Institute for Computer Sciences and Technology, the Office for Information Programs, and the

Office of Experimental Technology Incentives Program.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the United States of a complete and consist- ent system of physical measurement; coordinates that system with measurement systems of other nations; and furnishes essential services leading to accurate and uniform physical measurements throughout the Nation's scientific community, industry, and commerce. The Institute consists of the Office of Measurement Services, and the following center and divisions: Applied Mathematics — Electricity — Mechanics — Heat — Optical Physics — Center for Radiation Research — Laboratory Astrophysics 2 — Cryogenics 2 — Electromagnetics 2 — Time and Frequency*.

THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to improved methods of measurement, standards, and data on the properties of well-characterized materials needed by industry, commerce, educational insti- tutions, and Government; provides advisory and research services to other Government agencies; and develops, produces, and

distributes standard reference materials. The Institute consists of the Office of Standard Reference Materials, the Office of Air and Water Measurement, and the following divisions:

Analytical Chemistry — Polymers — Metallurgy — Inorganic Materials — Reactor Radiation — Physical Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides technical services developing and promoting the use of avail- able technology; cooperates with public and private organizations in developing technological standards, codes, and test methods; and provides technical advice services, and information to Government agencies and the public. The Institute consists of

the following divisions and centers: Standards Application and Analysis — Electronic Technology — Center for Consumer Product Technology: Product

Systems Analysis; Product Engineering — Center for Building Technology: Structures, Materials, and Safety; Building

Environment; Technical Evaluation and Application — Center for Fire Research: Fire Science; Fire Safety Engineering.

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts research and provides technical services designed to aid Government agencies in improving cost effectiveness in the conduct of their programs through the selection, acquisition, and effective utilization of automatic data processing equipment; and serves as the principal focus wthin the executive branch for the development of Federal standards for automatic data processing equipment, techniques, and computer

languages. The Institute consist of the following divisions: Computer Services — Systems and Software — Computer Systems Engineering — Information Technology.

THE OFFICE OF EXPERIMENTAL TECHNOLOGY INCENTIVES PROGRAM seeks to affect public policy and process

to facilitate technological change in the private sector by examining and experimenting with Government policies and practices in order to identify and remove Government-related barriers and to correct inherent market imperfections that impede

the innovation process. THE OFFICE FOR INFORMATION PROGRAMS promotes optimum dissemination and accessibility of scientific information generated within NBS; promotes the development of the National Standard Reference Data System and a system of in- formation analysis centers dealing with the broader aspects of the National Measurement System; provides appropriate services

to ensure that the NBS staff has optimum accessibility to the scientific information of the world. The Office consists of the following organizational units:

Office of Standard Reference Data — Office of Information Activities — Office of Technical Publications — Library

Office of International Standards — Office of International Relations.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D.C. 20234.

2 Located at Boulder, Colorado 80302.
Evaluation of

Automotive Fuel Flowmeters

Baldwin Robertson and

G. Paul Baumgarten

Institute for Basic Standards

National Bureau of Standards

Washington, D.C. 20234

Sponsored by:

U.S. Department of Transportation

Office of the Secretary

Office of the Assistant Secretary

for Systems Development and Technology

Washington, D.C. 20590

J0* 0f o0i

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

Issued June 1977
National Bureau of Standards Technical Note 943

Nat. Bur. Stand. (U.S.), Tech. Note 943, 95 pages (June 1977) CODEN. NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1977

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $2.30 Stock No. 003-003-01799-0
EVALUATION OF AUTOMOTIVE

FUEL FLOWMETERS

CONTENTS

Page

1. Introduction ,,,.,,.,,,, 1

2

.

Flowmeter Environment .,,.,..,,...«•«•*;. 3

2A Fuel Temperature and Vapor ....,,,,,..,.., 4

2B Fuel Color ............. 5

2C Swirl in Fuel Flow 5 2D Electrical Environment ..... 6

2E Flowmeter Attitude .... 6

2F Vibration Environment ...... 6

2G Flowmeter Installation 8

3. Apparatus 8

3A Vapor Seals, Vent Lines, and Bypass Lines 11

3B Apparatus for Other Tests 13

3C Vibration Apparatus 14

3D Electrical Test Apparatus 17

3E High Temperature Apparatus ..... 18

4. Procedure 20

4A Scope 20

4B Summary of Procedure 20

4C Apparatus 20

4D Preparation for Tests 21

4E Procedure for Steady flow Tests 21

4F Procedure for Unsteady Flow Tests 24

4G Procedure for Vibrational Tests 25

4H Procedure for Electrical Tests 27

41 Procedure for Variable Pump Speed Test 27

4J Procedure for High Fuel Temperature Tests . 28

5. Error Analysis 29

5A Summary of Potential Errors 32

6. Test Results 34

6A Four Orifice Flowmeter 34

6B Four Piston Flowmeter 39

6C Positive Displacement Pump Flowmeter 46

6D Turbine Flowmeter .53

6E Automatic Burrette Flowmeter .... 62

6F Ball-in-Race Flowmeter 62

6G Ball and Spring Flowmeter 68

7. Discussion and Conclusion ..... 73

Appendix. Flowmeters 74

A. Four Orifice Flowmeter . 74

B. Four Piston Flowmeter 76

C. Positive Displacement Pump Flowmeter 76

D. Turbine Flowmeter ....... 76

E. Automatic Burrette Flowmeter 79

xn
Page

F. Ball-in-Race Flowmeter .... 79

G. Ball and Spring Flowmeter 79

H. Thermistor Calibration 83

References 88

LIST OF TABLES

Table 6A. 1 Table 6A. 2 Table 6B. 1 Table 6B. 2

Table 6C. 1 Table 6C 2 Table 6D. 1 Table 6D. 2 Table 6D. 3 Table 6D. 4 Table 6F 1

Table 6F 2

Table 6G. 1 Table 6G. 2

Four Orifice Flowmeter 37

Four Orifice Flowmeter 38

Four Piston Flowmeter 39

Four Piston Flowmeter 41

Positive Displacement Pump Flowmeter 48

Positive Displacement Pump Flowmeter 49

Turbine Flowmeter 55

Turbine Flowmeter 55

Turbine Flowmeter 56

Turbine Flowmeter 61

Ball-in-Race Flowmeter 63

Ball-in-Race Flowmeter 64

Ball and Spring Flowmeter 68

Ball and Spring Flowmeter 69

LIST OF FIGURES

Figure 3.1:

Figure 3.2:

Figure 3.3:

Figure 3.4:

Figure 3.5:

Figure 4.1:

Figure 5.1:

Figure 5.2:

Figure 6A.1

Figure 6B.1

Figure 6B.2

Figure 6B.3

Figure 6B.4

Figure 6B.5

Figure 6C.1

Figure 6C.2

Figure 6C.3

Figure 6C.4

Test Set-Up Schematic 9

Weigh tank and Vapor Seals 12

Wiring Schematic for Vibration 15

Test Set-Up for Vertical Vibration 16

Schematic of High Temperature Test Set-Up ... 19

Graph of Total Mass Weighed Versus Time,

Illustrating the Substitution Weighing Procedure 23

Error Due to the Additional Fuel Collected ... 30

Response of the Beam Balance with the Weigh

Tank Nearly Empty and Again with the Tank Full . 33

Four Orifice Flowmeter Calibration Curve .... 36

Four Piston Flowmeter Calibration Curve .... 40

Vertical Vibration Test of the Four Piston

Flowmeter 42

Vertical Vibration Test of Four Piston Flowmeter 43

Vertical Vibration Test of Four Piston Flowmeter 44

Horizontal Vibration Test of Four Piston

Flowmeter 45

Calibration Curve for the Positive Displacement

Pump Flowmeter 47

Effect of Supply Voltage on the Positive

Displacement Pump Flowmeter with an Actual

Flowrate of 10 g/s 50

Erratic Pulse Output of the Positive

Displacement Pump Flowmeter 51

Erratic Pulse Output of the Positive

Displacement Pump Flowmeter 52

IV
Page

Figure 6D.1:

Figure 6D.2:

Figure 6D.3:

Figure 6D.4:

Figure 6D.5

Figure 6F.1

Figure 6F.2:

Figure 6F.3:

Figure 6G.1:

Figure 6G.2:

Figure 6G.3:

Figure A:

Figure B: Figure C:

Figure E.l:

Figure E.2:

Figure G:

Turbine Flowmeter Calibration Curve 54

Erratic Pulse Output of the Turbine Flowmeter . 57

Vertical Vibration Test of the Turbine

Flowmeter 58

Effect of Vibrating the Turbine Flowmeter

Horizontally and Perpendicular to the Flow

Direction 59

Effect of Vibrating the Turbine Flowmeter

Horizontally and Parallel to the Flow

Direction 60

Ball-in-Race Flowmeter Calibration Curve ... 65

Vertical Vibration Test of Ball-in-Race

Flowmeter 66

Ball-in-Race Flowmeter Vibrated Horizontally

in Direction of Inlet and Outlet Fuel Lines . . 67

Ball and Spring Flowmeter Calibrator 70

Ball and Spring Flowmeter Calibration Curve . . 71

Ball and Spring Flowmeter Indicated Flowrate

Versus Time 72

Four Orifice Flowmeter 75

Four Piston Flowmeter 77

Positive Displacement Pump Flowmeter 78

Automatic Burette Flowmeter 80

Automatic Burette Flowmeter 81

Ball and Spring Flowmeter 82

Evaluation of Automotive Fuel Flowmeters

Baldwin Robertson and G. Paul Baumgarten

Fuel economy measurement procedures being developed by tbe Transportation

Systems Center of the Department of Transportation require flowmeters to

measure the gasoline consumed by the engine of an automobile either on

the road or on a dynamometer. The contribution of the National Bureau

of Standards to this work was to ascertain the environment in which the

flowmeters will probably be used, to develop procedures for measuring

their performance in a laboratory simulation of that environment, and

to carry out illustrative measurements on a number of flowmeters.

This report discusses: (1) the environment of the flowmeter in an automobile, i.e., flowmeter temperature; fuel temperature, pressure, density,

viscosity, color, opacity, flow pulsations, back flow, and swirl due to

elbows; line voltage fluctuations; electromagnetic radiation from ignition;

vehicle attitude with respect to the vertical; and vibration, (2) the

test set-up and procedure used for eavluating and calibrating these meters

in the laboratory under conditions simulating the automotive environment,

(3) a discussion of possible sources and magnitudes of errors in the

calibration, and (4) results of illustrative tests on seven flowmeters.

Keywords: automotive environment; automotive fuel flowmeters; effect

of environment on flowmeter performance; flowmeter calibration; flowmeter

evaluation; procedure for testing flowmeters.

1 . INTRODUCTION

The Automotive Energy Efficiency Program of the Department of Transportation

(DoT) has needed reliable calibration and evaluation of flowmeters in order

to study various proposed schemes for conserving automobile fuel. The

Fluid Meters Section of the National Bureau of Standards (NBS) was asked

to develop a procedure for doing this because of its experience with the

calibration of flowmeters suitable for liquid hydrocarbons.

The flowmeters to be tested are of the kind used by DoT to measure the

flow of gasoline to the carburetors in fleets of automobiles as well

as in special test vehicles and on engine test stands. The procedure

involves using gasoline under conditions that simulate the environment

expected for flowmeters in automobiles. This is necessary because the

hostile conditions that can exist in an automobile may cause the flowmeter to give a reading that is incorrect by a factor of two or more.

For example, engine heat causes vapor bubbles to form in the gasoline.

If they are metered along with the liquid, a substantial increase in

flowmeter indication will result. But even if bubbles form only downstream of the meter, they cause backflow through the flowmeter when they

expand during the backstroke of the automobile fuel pump. Some flowmeters count the backflow as if it were forward flow and hence make a large error in measuring the net flow.

- 1 -
In the procedure the basic test of a flowmeter is a calibration

performed at room temperature by weighing the amount of gasoline

collected during a measured time interval. The apparatus used is

designed so that although the flow is steady where it goes into the

weigh tank, it pulsates where it is metered as in the automotive

environment. This is done by using an automotive fuel pump and the

float bowl assembly from a carburetor. Flowrates used range from

0.2 to 20 g/s, and precision attained is better than 0.05 percent.

Other laboratory tests to be performed involve simulating a variety

of operating conditions which may be adverse to dependable meter

performance. These include: unsteady flow to simulate the effects

of throttle opening and closing; fuel pump speed changes from 190

to 1900 pulses per minute to simulate changes in engine speed;

horizontal and vertical vibration of meter and float bowl at the

smaller of 2.5 cm displacement or 0.5 x 980 cm/s 2 acceleration over frequencies from 1 to 1000 Hz to simulate road and engine vibration;

supply voltage changes to simulate battery discharge, accessory

switching, or alternator output changes; electromagnetic radiation

from a spark plug wire to simulate radiation from ignition wiring;

and temperatures from 20°C to 65°C to simulate the effects of ambient

temperature changes and engine heating. The last test required elaborate

precautions in order to minimize the chance of explosion during the

tests.

Seven flowmeters were tested to illustrate the use of the procedure.

They include four of the larger more expensive commercially available

flowmeters and three smaller ones, which are. inexpensive enough to be

considered for installation in every automobile sold. It should be

emphasized that only selected results are reported here, that only one meter of each kind was tested, and that the present results may not

reliably indicate how other meters made by the same manufacturer will

perform. Because only limited time was available, a comprehensive

series of tests to fully characterize the dynamic performance of these

flowmeters has not been performed. Some of the tests, e.g. the high

temperature test, which is one of the most important tests, have been

carried out on only one flowmeter. As a result the present data should

not be used in an estimation of how a particular flowmeter will perform

on an automobile under actual driving conditions.

Section 2 describes the automotive environment that may be expected

to possibly affect flowmeter accuracy. Section 3 describes the apparatus

used for determining flowmeter accuracy in a laboratory simulation of

that environment. Section 4 describes the test procedure. Section 5

discusses potential sources of error and gives estimates for the magnitudes

of errors that do occur. Section 6 presents test results for seven flowmeters. Section 7 gives a brief discussion. The Appendix gives a functional description of the flowmeters that were tested, and gives

Reports of Test of the thermister probes used for measuring temperature.

- 2 -
2. FLOWMETER ENVIRONMENT

The flowrate of gasoline to the carburetors of automobiles can be

as low as .4 m£/s (.4 gallons/hour) for a small car at idle. It can

be as high as 22 m£/s (22 gallons/hour) for a large car at full load

going up hill at high speed. This is a range of over 50 to 1. The

flowmeters available to measure this flow range in mass from .5 to

11 kg and in size from those that fit in your hand up to a cube about

30 cm on a side. In addition some have remote readouts that are to

be put on the dash to make it easy to record the measured results.

The larger flowmeters are intended to be placed on the floor in front

of the right front seat of the car. The fuel lines lead out the window

over the fender, through the grill, and to the engine. Smaller flowmeters are to be mounted on the front bumper, elsewhere outside the

car, or on a long bracket attached to the automobile body under the

hood. The smallest flowmeters are supported by the fuel line itself;

one is to be near the fuel pump, and one near the carburetor.

Regardless of where the flowmeter is placed in or on the car, its

input and output lines usually have to be connected between the fuel

pump and the carburetor. Many cars have a fuel pump with three fuel

lines connected to it. One line comes from the tank, one goes to the

carburetor, and a vapor diverter line goes back to the tank. The

vapor diverter line is connected to a small orifice at the top of

the output fuel passage. Bubbles which rise to the top of the gasoline

in the passage go through the orifice and are carried by the diverter

line back to the tank. This helps prevent vapor lock. However, the

diverter line also carries a large flow of liquid gasoline back to the

tank. If the flowmeter were connected into the line from the tank to

the pump, it would measure the flow to the carburetor plus the flow

back to the tank. On these cars the flowmeter must be connected so that the fuel flows from the pump to the flowmeter and then to the

carburetor. Only then will it measure just the flow to the carburetor.

On some cars the diverter is mounted on the fuel line just a short

distance from the carburetor. The diverter line leads from there

back to the tank. For these cars the flowmeter must be connected

between the diverter and the carburetor.

The environment of the flowmeters in an automobile is complex and

rather hostile. It is complex because there are several possible

locations in which to place the flowmeters, quite a few physical

variables to be considered, many different makes and models of

cars, and a broad range of conditions under which the cars will

be operated. In principle, the environment could be expressed

- 3
more simply in terms of the flowmeter locations, the physical

variables, and the range of values that these variables take

for these locations. However, the problem remains in getting

the data for the normal operating conditions that occur in the

tests by DoT.

Unfortunately we could not solve the problem by just going out

and measuring the variables we want to know. First, many of the

measurements would have to be made on 1976 cars since they differ

in several important ways from earlier ones. Second, the tests

would have to be performed on a representative sample of makes

and models of cars. Third, they would have to be performed

under a complete range of weather conditions. Fourth, we did

not have the time nor all of the instruments. The time and

expense involved is obviously enormous. We must rely on measurements taken by others, and these appear to be somewhat limited.

We do have the recommended standards and test methods published

by the Society of Automotive Engineers 1 and other sources. 2 Unfortunately, much of the data either applies to 1972 or earlier

cars or applies to test conditions that are much more extreme

than occur in the tests by DoT. However, conversations with

several people 3 in the research laboratories of automobile

manufacturers as well as with others provided some data that

applies to the conditions of the DoT tests. The following data

was obtained from these sources.

2A Fuel Temperature and Vapor

The temperature of the fuel in the fuel lines can range at least

between -10° C (15°F) and 65 to 77°C (150 to 170°F) . The result

is a 10 percent change of density and a change by a factor of 2 in the kinematic viscosity. This will certainly affect the

performance of some of the flowmeters. However, there are potentially much larger effects at the higher temperatures.

Depending on what week of the year and in what part of the country

the gasoline is purchased, vapor bubbles can form in the fuel

line at temperatures above 50°C (120°F) to 70°C (160°F) . These

bubbles or even ordinary air bubbles in the fuel reduce the average

density of the fuel much more than ordinary thermal expansion of

the liquid. If the bubbles are in the fuel that is measured,

they can cause large errors in the reading of most flowmeters, even apart from the backflow effect to be described later. Some

flowmeters have vapor diverters, which are intended to eliminate

the bubbles just before the fuel is metered. Even so, bubbles

will form again inside the meter. If they do, the measured flowrate

can be in error by a factor of two or so.

- 4 -
But even if there are no bubbles in the fuel that is measured there

can be a substantial effect due to bubbles formed in the fuel line

between the meter and the carburetor, i.e., downstream of the meter.

On hot days it is not unusual to find 50 to 80 percent of the volume

inside the fuel line occupied by the bubbles. The effect of this

on the flowmeter is due to the pulsating fuel pump pressure, which

can vary in the range from 20 to 50 kPa (3 to 7 psi) on cars with

a vapor diverter. When the pressure drops due to flow back through

the vapor diverter, the gas bubbles get larger according to the

gas law. New bubbles may even form since the solubility

of the more volatile components in the gasoline has been lowered

by the decrease in pressure. The increase in volume of the fuel

because of the bubbles causes fuel to flow backwards through the

meter. Some flowmeters will not count this backflow, others will

count it as if it were ordinary forward flow. Then on the next

fuel pump stroke, the pressure increases, the bubbles collapse

and may even disappear, and the fuel that once flowed backward

now flows forward through the flowmeter, getting counted once

again.

The effect is particularly large when the engine is shut off. Then

the fuel line pressure drops to zero, and the bubbles and gravity

can cause the entire contents of the fuel line (more than 100 cm3

) to flow backwards through the flowmeter.

There is another possible cause of pulsations in fuel flow that can occur even when bubbles are not present at all. The needle

valve in the float bowl of the carburetor may tend to be either

appreciably open or closed entirely, rather than somewhere in

between. Thus the flow may tend to stop and start and this may

affect the accuracy of some meters

Besides the change in fuel density and viscosity due to temperature,

there can be a change of roughly 3 percent in density and 25 percent

in kinematic viscosity depending on the week and place of purchase.

2B Fuel Color

Another property of the gasoline may also affect flowmeter performanceits opacity due to its color: red for premium, orange for regular,

clear for unleaded, and brown for tax-free off -road use. If the

gasoline is unusually strongly colored, the light beam going through

it in some flowmeters may not be intense enough to be detected.

These flowmeters will then give erratic readings or record no flow

at all.

2C Swirl in Fuel Flow

Turbine meters may be affected by swirl in the fuel flow. The swirl can be generated by centrifugal force if the fuel flows through

elbows. This swirl may add to the rotating motion of a turbine

rotor

- 5 -
2D Electrical Environment

All but one of the meters described use electrical power from

a 12-volt battery. If this is the car battery there may be

undesirable effects due to fluctuation in the voltage supplied

to the meter. On a normally operating automobile, the DC line

voltage can range between 9 and 16 volts depending on the

condition and state of charge of the battery and the rate of

charge by the alternator. In addition there can be undesirable

noise voltages on the line. Automobile accessory and normal

ignition noise on the line can be as big as 3 volts peak. Also

when the ignition switch is shut off there can be a -100 volt

pulse on the line due to an inductive load on the line such as the alternator or an accessory. These voltage fluctuations may

affect flowmeter accuracy. However, the effect of the noise

and transient voltages can be reduced if the flowmeter is connected

directly to the battery.

Another possible source of flowmeter inaccuracy is the electromagnetic radiation from electronic ignition systems in normal

operation. This may disturb the electronic circuitry in some flowmeters that are not properly shielded.

2E Flowmeter Attitude

Some meters may have their accuracy affected by a change in attitude

of the meter with respect to the vertical as the car goes up or down

hill or around a banked turn. The maximum grade on a hill is usually

9 percent, and the maximum banking on a curve is usually 6 percent

(10 percent if in a location where ice and snow is unlikely). **

2F Vibration Environment

The vibration environment of the flowmeters is complex. Assuming

that the flowmeter as a whole is a rigid body it has six vibrational

degrees of freedom: three translational and three rotational, one about each of the three axes. Each of these modes of vibration

can have many frequencies and intensities. The details depend

strongly on the exact location of the flowmeter in the car, the

make and model of the car, the balancing of the wheels, the

smoothness of the road, the speed of the engine, and the speed

of the car. There are a lot of variables, and very little data

is available.

The SAE publication 1 characterizes the vibration caused by driving

on a very rough test track: the Belgium Block Road, the Hop, the

Tramp, the Square Block Test Course, and other complex surfaces.

It specifies sinusoidal test vibration levels of 2.5 cm peak to

peak displacement from 1 Hz to 5 Hz and 1.5 x 980 cm/s 2 acceleration

from 5 Hz to 1000 Hz to simulate interior and under hood vibration,

and a similar sweep at 2.5 cm and 4 x 980 cm/s 2 for the exterior

and chassis. These vibration levels are probably much more severe

than those to be expected during the TSC tests on smooth roads or

test tracks.

- 6 -
A lower vibration level has been proposed by the Packaging Committee

of ASTM in a test procedure for packages shipped on a truck. This

test procedure specifies vibrating at . 5 x 980 cm/s2 acceleration.

However, the suspension of an unloaded truck is much stiffer than

that of an automobile. So the amplitude of the vibration is

probably larger than expected for a flowmeter inside the car during

the DoT tests.

A much lower vibration level has been measured by the Noise, Vibration

and Harshness Division of an automobile manufacturer. They 5 report

a peak acceleration of .05 x 980 cm/s 2 on the dash of a car on a nearly perfectly smooth road with wheels balanced dynamically.

However, wheel balancing for mass production is static rather than

dyamic , and since the test road may not be perfectly smooth, the

vibration levels during the DoT tests could be much higher.

Some understanding of the vibration of an automobile on a smooth

road can be gained by the following general considerations. The

most obvious of the low frequency resonances observable on the

floor of an automobile are reported to be at roughly 1 Hz , 10 Hz

,

14 Hz, and 20 Hz. The exact values vary substantially from car

to car. The approximately 1 Hz resonance is due to the vertical

motion of the entire car on its four springs and tires. Even on

a particular car, this resonant frequency can change since it

depends upon the pressure. The 10 Hz and 14 Hz resonances are associated with bending and torsion of the car body. The 20 Hz

resonance occurs in the vibration of the floor pan itself. Of course there are many other possible resonances that appear throughout a broad frequency band.

All these resonances are excited to varying degrees depending

upon the degree of balance of the wheels, the smoothness of the

road, and the speed of the car. For just one example, at 24.5

m/s (55 MPH) the speed of a 76 cm (2.5 ft) diameter tire is about

10 rev/s. Thus if the wheel is even slightly out of balance,

there will be a 10 Hz vibration source, which will resonate with

the car. Of course the numbers vary from car to car, and the

frequency of the vibration source obviously varies with speed.

Also, there are many other resonances that can be excited.

Only a very sketchy discussion of the relevant vibration environment

has been presented. A realistic characterization of vibration at

the different flowmeter locations in a car on a smooth road is not

available.

- 7 -
2G Flowmeter Installation

One last comment should be made on the Installation of flowmeters,

It is desirable that the flowmeter not affect the performance of

the car. There are three ways this might happen. First, the

pressure drop across the meter might be an appreciable fraction

of the fuel pump pressure. Whether this happens with steady fuel

flow or only when the flow suddenly increases by a sudden opening

of the throttle, the engine could be deprived of fuel, and its

performance affected. Second, some flowmeters smooth out the

pressure pulses from the fuel pump. The effect of this might

be to lower the fuel level in the carburetor float bowl, and

that could affect engine performance or fuel economy. Third,

the extra load on the engine due to the electric power drawn

from the car's electric system by one of the flowmeters is about

one horsepower. This will affect fuel economy measurements. It can be avoided by powering the flowmeter by separate batteries.

But then the mass of these batteries plus the flowmeter and its

converter might affect the performance of the car, especially if

it is a small car.

3. APPARATUS

It is essential to use gasoline for the tests in order for the

metered fluid to have the correct density, viscosity, lubricity,

and volatility. Because of this the tests must be done in a special laboratory that has forced ventilation with exhaust inlets

at floor level. In order to meet the electric code, every

electrical part must be either in an explosion-proof enclosure

with explosion-proof fittings, in an ordinary enclosure that is

purged with fresh air, or in a nearby room in which there is no gasoline and which is ventilated with fresh air at a small

positive pressure. In addition special precautions should be

taken to prevent evaporation of the gasoline.

A schematic of the test set-up is shown in Fig. 3.1. The flowmeter

under test is connected between an automobile fuel pump and the

float bowl of a carburetor. The fuel pump pumps gasoline from

the storage tank through the meter and the needle valve into the

float bowl. Another pump pumps the gasoline from the float bowl

through the transfer standard meter and the flow adjusting valve

into the weigh tank. When the dump valve is open the gasoline

flows by gravity from the weigh tank into the storage tank.

The automotive fuel pump is a mechanical one that is normally driven

by a cam on the cam shaft of an engine. This rotates at half engine

speed, and hence the pump operates in the range from 225 ppm (pulses

per minute) to 1800 ppm. For the laboratory tests, the

- 8 -
VENT LINE FLOAT BOWL

ASSEMBLY

CONSTANT

VOLUME

PUMP

PRESSURE

REGULATOR

TRANSFER

STANDARD

METER

PRESSURE RELIEF VALVE

FLOW

ADJUSTING

VALVE

WEIGH

TANK

VAPOR RETURN

SHUT OFF VALVE

METER

UNDER

TEST

AUTOMOBILE

FUEL PUMP •GASOLINE FLOW

VENT

LINE

STORAGE

TANK

VENT TO ATMOS.

Fig. 3.1. Test Set-up Schematic. The flowrate through the meter

under test is set using the flow adjusting valve.

- 9 -
automotive fuel pump is driven by an explosion-proof motor

connected to a variable speed drive with an automobile cam on

it. The speed range possible is 190 ppm to 1900 ppm. The

speed is measured using a 160 tooth gear on the output shaft

with a magnetic sensor to detect the passage of each tooth

and an electronic counter to count the resulting pulses. The

fuel pump has a 1/4 inch diverter line leading back to the

storage tank. This line can be closed off in order to simulate

automobiles without a diverter.

The gasoline lines are either 3/8 inch stainless steel tubes

or 3/8 inch hard flexible plastic tubing connected together with

stainless steel or nylon fittings. Copper or brass can not be

used because they cause gasoline to form gum especially at higher

temperatures. Soft distensible tubing can not be used between

the automotive fuel pump and the float bowl because it might

affect flowmeter performance. The gasoline lines should slope

upward everywhere in order to encourage bubbles to be carried

along with the liquid flow.

The needle valve, float, and bowl assembly is one that can be

purchased separately as a replacement part for an automobile

carburetor. The open side where the bowl normally attaches

to the carburetor is covered with a transparent plastic plate

so that the liquid level can be observed during nonsteady flow

experiments. For steady flow, at least, the fuel pump supplies

enough fuel so that the liquid level in the float bowl remains

nearly constant regardless of the flowrate.

Since the pressure regulator maintains a constant pressure at

its output, the flowrate for the entire flow around the system

is set by the flow adjusting valves. These are needle valves,

one 3/8 inch and one 1/4 inch size, in parallel just upstream

of the weigh tank. The flow from each valve spills separately

into the weigh tank and drains into the storage tank when the shut

off valve is open. The pipes leading into and out of the tank

are arranged so that they do not interfere with the weighing.

Substitution weighing (to be described in the next section) is

used to determine the mass of the fuel collected. The tank is

suspended from one pan of an equal arm balance with a distance

of 16 cm from the center to either pan. A weight whose mass equals

the mass of gasoline to be measured is placed on the pan from

which the tank is hung. A set of Class C brass weights including

200 g, 500 g, and 1 kg masses is used for this purpose. A counter

weight is kept on the pan that hangs from the other end of the

balance arm. This weight is more than large enough to balance

the weigh tank plus the substitution weight so that with no gasoline

in the tank the tank end of the balance arm is up and the other

end down.

- 10 -
Tilting of the balance arm is detected by a photon coupled

interrupter module. This consists of a light emitting diode

shining light onto a photo-Darlington. With the weigh tank

empty, a tab on the balance pointer blocks the light beam.

When the tank fills and the balance arm swings, the tab moves

unblocking the light. This causes the output voltage of the

photo-Darlington to decrease monotonically with the lowering

of the weigh tank. The output voltage is connected to the

gating circuit of an electronic counter, which is set up so that the decreasing voltage starts the counter the first time

the voltage decreases and stops the counter the second time.

The photo-Darlington output is also amplified and used to

energize a relay that turns on a 100 Watt light bulb when

the weigh tank is down. The light helps remind the operator

to remove the substitution weight the first time it turns

on and to open the shut-off valve and replace the substitution

weight the second time it turns on.

3A Vapor Seals, Vent Lines, and Bypass Lines

The weigh tank is equipped with two vapor seals designed to minimize

the escape of vapor during the measurement and at the same time

leave the tank unhindered for weighing. There are two seals, one

at the top and one underneath the tank. Each consists of an oil

filled circular moat with the edges of a concentric inverted cup

immersed in the oil (Fig. 3.2). At the top of the tank, the

inverted cup has rigid tubing going through it and so is fixed.

The moat it dips into is attached to the top of the weigh tank.

Underneath the tank, the inverted cup has the rigid tube from

the shut-off valve going through it. So it will swing-free with

the tank and shut-off valve. Here, it is the oil filled moat that

is fixed since it is attached to the discharge stand-pipe. The

empty tank and the valve altogether have a mass of 2545 g.

A vent line connects the weigh tank, the stand-pipe, and the storage

tank. This is necessary to provide a return for the vapor that is

displaced when the weigh tank is dumped by opening the shut-off valve.

The vapor volume flowrate from the storage tank to the weigh tank

must be at least as large as the liquid volume flowrate, which can be

large when a full tank is dumped. In addition vapor will be entrained

by the liquid jetting into the weigh tank from the flow adjusting

valve. This vapor is carried with the liquid into the storage tank

and released when the liquid settles down. The pressure drop in the

vent line due to the (total) vapor flow must be kept small enough so that air does not gurgle through the oil filled moat. The gurgling

would cause oil to spill into the weigh tank and mix with the gasoline,

A 3/8 inch vent line is large enough to prevent gurgling when using

the tank of Fig. 3.2 provided the 3/4 inch shut-off ball valve is

not opened all the way at first when a full weigh tank is dumped. A

3/8 inch ball valve would probably have been large enough and probably

could be opened completely without causing gurgling when dumping.

- 11 -
Fuel to be Weighed Vei

Inverted Cup (Fixed)

Oil Filled Circular Moat - Swings With Tank

22 cm

Volume = 3.9 Liters

15cm

Shut Off Valve

-Weigh

Tank

Swings

Freely

Oil Filled Circular

Moat (Fixed) — i£ h

Handle

Inverted Cup

Swings With Tank

Stand-pipe Discharges

to Storage Tank

Fig. 3.2. Weigh tank and Vapor Seals. The oil filled moats

prevent vapor from escaping and do so without interfering with

the weighing.

12 -
A vent line is connected between the float bowl assembly and the

weigh tank, and a 1 meter long vent line is connected from the weigh

tank and storage tank vent line to the atmosphere. The open end of

the latter is placed inside the explosion-proof room-exhaust duct

in order to keep gasoline vapor out of the room. The line to the

atmosphere is long enough that after the entire system settles to

a steady state only gasoline vapor (and no air) will be in the vent

lines.

In addition to the vent lines, there are bypass lines from the main

gasoline line just above the flow adjusting valves, from the bypass

outlet of the transfer standard meter, and from the bypass or vapor

diverter outlet (if one exists) of the meter under test. These lines

(not shown in Fig. 3.1) all lead to the storage tank. The vapor

diverter line is left connected according to the instructions of

the manufacturer of the meter under test. The bypass lines, on the

other hand, are used only momentarily to bleed air and vapor bubbles

out of the gasoline lines when the system is turned on. Hence they

normally are closed off by valves, which are located at the gasolineline end of the bypass lines. All the bypass and diverter lines are made of clear plastic to permit visual inspection for bubbles, e.g.,

to determine when the lines have been bled enough.

3B Apparatus for Other Tests

The Four Orifice Flowmeter described in Appendix A is used for the

transfer standard flowmeter in Fig. 3.1. It is included in the test

set-up in order to increase the rate of taking data during tests other

than the calibrations. The tests involve changing fuel temperature,

vibrating the flowmeter under test, etc., and observing whether the

indication of the flowmeter under test changes while the flowrate, as measured by the transfer standard flowmeter, is held constant. The

transfer standard flowmeter operates at room temperature and is not

vibrated or otherwise disturbed. Of course the accuracy of the data

taken in these tests is limited by the accuracy of the transfer standard

flowmeter, which is not as accurate as weighing and timing. But the

transfer standard used, when its voltage output is connected to a voltageto- frequency converter, gives one pulse for each milligram of gasoline

passing through it. This fine resolution makes it possible to determine

quickly the effect on flowmeter indication of changing many variables

one at a time over a large range. This is necessary when the effect

on flowmeter indication is small and turns out to occur only over a small part of the range of only one variable. Such a small effect, in

spite of its importance, would probably be missed altogether if only

weighing and timing were possible because the latter is so time consuming

and so would be done for only a few widely-spaced selected values of the

variables.

The pulse output of the transfer standard is connected to the A

input of an electronic counter, the pulse output of the flowmeter being

tested is connected to the B input, and the counter is set to count the

number of A pulses between one B pulse and the first, tenth, or one hundredth B pulse that follows. The counter thus displays the ratio

- 13 -
of flowrates, and this display is automatically updated at an adjustable rate. Any three adjacent digits of this ratio are converted

into a voltage by a digital-to-analog converter built into the counter.

The voltage is connected to the Y input of an XY recorder as shown

in Fig. 3.3. By choosing three digits other than the most significant

ones and by increasing the Y axis gain of the recorder, the vertical

scale of the graph can be expanded as much as desired. A voltage

proportional to the variable being changed in the test is connected

to the X input. Thus the recorder will plot the ratio of the "actual"

flowrate to the indicated flowrate of the flowmeter being tested on

the Y axis versus the changing variable on the X axis, where the

"actual" flowrate is given by the undisturbed transfer standard flowmeter.

X inputs to the recorder that are possible with the present apparatus

include

- Flowrate, 0.2 to 20 grams per second

- Logarithm of vibration frequency, 1 to 5000 Hz.

- Peak acceleration, to 10 x 980 cm/s 2

.

- Automobile fuel pump speed, 190 to 1900 pulses per minute

- DC supply voltage, 8-16 volts

- Amplitude of 60 Hz voltage superposed on supply.

The pump-speed voltage is obtained from a digital-to-analog converter

in the counter used to measure the speed

3C Vibration Apparatus

The vibration exciter is shown at the lower right of Fig. 3. A. It is an electrodynamic exciter mounted with a 61 cm square granite slab for

a slip plate all on a reinforced concrete seismic base. The entire

assembly weighs 5200 lbs (23,131 N) and is supported on inflated air

mounts. The air mounts are connected to an air tank with damping

orifices in order to permit operation down to 1 Hz without excessive

excursion of the seismic base. The peak force available is 800 lbs

(3559 N) , and the armature suspension stiffness is 400 lbs/inch (700 N/cm)

Thus a 30 lb (133N) flowmeter, which is mounted on a 41 cm square by

5 cm thick fixture weighing 50 lbs (222 N) and attached to the 20 lb

(89 N) armature, can be vibrated vertically without overwhelming the

exciter. The mounting hole pattern on the 61 cm square by 3.18 cm

slip plate is identical to the 20.32 cm diameter pattern on the armature . so that after a flowmeter is vibrated vertically, the flowmeter and

fixture can be remounted on the slip plate for horizontal vibration.

- 14 -
7 TTl 6

FREQUENCY RATIO

COUNTER

TRANSFER

STANDARD

METER

METER

UNDER

TEST

o

Y in

TEST VARIABLE

DIGITALANALOG

CONVERTER

18.13 volts

Fig. 3.3. Wiring Schematic for Vibration,

Supply Voltage, Fuel Pump Speed, and other tests.

- 15 -
Fig. 3.4. Test Set-Up for Vertical Vibration. The flowmeter being

tested is connected directly to the float bowl assembly, which is

mounted on an angle iron on top of the exciter (lower right) . For

horizontal vibration, the angle iron is remounted on the slip table

(one corner just visible at lower center), and the exciter is rotated

90° on its trunnion and attached to the slip table. The variable speed

motor (lower right) has the automotive fuel pump attached to it. The

four orifice flowmeter is just right of center, and the pressure regulator and supply pump used with it are to its left. The stainless

steel weigh tank (center right) hangs from a pan with a substitution

weight on it. The pan hangs from a balance arm (upper right) which

has another pan on the other end with a counter weight on it. Electronic

counters etc. are behind the window and to the left (not visible in the

picture) and can be seen by the operator when standing at the weigh

tank. The counters can be reset remotely by pushing explosion-proof

pushbuttons.

- 16 -
The sinusoidal vibration can be swept automatically from 1 Hz to

1000 Hz or from 5 Hz to 5000 Hz or over an arbitrary range within

either of these. In this frequency range, the vibration level can be

up to 2.54 cm peak-to-peak displacement, 71 cm per second velocity,

or 800 lbs (3559 N) force, whichever is smallest considering the frequency

and the weight of the flowmeter, fixture, and armature. The displacement, velocity, or acceleration can be automatically controlled at

presettable levels in each of two segments in the range from 1 to

5000 Hz with automatic crossover between segments at a presettable

frequency, all presettable before vibrating. The vibration test

system has overload and over driving protection and interlocked

controls for damage protection. Vibration frequency is displayed

to .1 Hz once every second or to 1 Hz ten times a second. Two

vibration monitors each display displacement, velocity, or acceleration with an accuracy of 1 percent of reading in the range from 1 to 5000 Hz. The accelerometers used with the monitors are: one high

sensitivity (100 mv per 980 cm/s , rms) accelerometer, and one subminiature one with a total mass of 1 gram, both of them the shear mode

piezoelectric kind.

The shaker and slip table assembly are modified for use in an explosive atmosphere. The field power supply, power amplifier, and

other vibration system electronics are mounted in a standard electronics

rack located in a room adjacent to the explosion-proof laboratory.

Once a flowmeter has been fixtured to the armature the shaker can also be used to tilt the flowmeter 10 degrees or any other angle from

the vertical. The shaker is designed to be rotated on its trunnion

from the vertical position to the horizontal position for attaching

it to the horizontal slip table. However, the shaker can be locked

at any angle and can be used just as a mechanical support without

any power supplied to it to make it vibrate.

3D Electrical Test Apparatus

Three automotive 6 volt lead storage batteries provides voltages

in 2 volt increments up to 18 volts for flowmeters that require a large current. A regulated power supply provides a continuously variable

voltage up to 18 volts for flowmeters that require less than 3 amperes.

A 120 volt to 12 volt transformer with the primary connected to a variac

and the secondary wired in series with the dc supply provides a 60 Hz

sinusoidal voltage of variable amplitude superposed on the dc supply

voltage. An automotive spark plug, coil, and capacitive discharge

ignition source driven by a +5 volt pulse generator and a transistor

provide a spark for testing the effect of electromagnetic radiation

on flowmeter performance. An "antenna" made of ignition wire is attached

to the hot side of the spark plug and taped to the window near the

flowmeter. Radio noise suppression ignition wire and, alternatively,

insulated metallic ignition wire are used for the antenna.

- 17 -
3E High Temperature Apparatus

For high temperature measurements heat exchangers are installed

as shown in Fig. 3.5. The one used for heating the gasoline just upstream

of the meter under test consists of three single pass sections,

two of them each 100 cm long and one 130 cm long, connected in series

in a Z configuration using 3/8 inch elbow tubing fittings. Each section

consists of a long straight 3/8 inch stainless steel tube (with the

gasoline flowing inside it) and a shorter concentric 5/8 inch stainless

steel tube (with hot water flowing in the annular region between the

tubes. The water enters through the branch of a 5/8 inch stainless

steel T fitting at one end and leaves through a similar setup at the

other end. A bored through 5/8 to 3/8 inch reducing fitting keeps

water from leaking out the end and holds the 3/8 inch tube concentric

with the run of the T and hence with the 5/8 inch tube. The hot water

circulates at 15 2,/min through 1/2 inch plastic tubing from a constant

temperature circulator consisting of a 1000 watt heater, a pump, and

a thermostat. The circulator is located in the next room in order to

meet the explosion-proof requirements. All tubes are covered with two

layers of 1.25 cm thick foam pipe insulation.

The three heat exchangers used to cool the gasoline liquid and

vapor each consist of 28 straight-through 1/4 inch tubes in parallel.

One fluid flows inside the tubes and the other passes back and forth

around the outside of the tubes and inside a 5.14 cm diameter jacket.

The two heat exchangers used to cool vapor in the vent lines each

have 20 cm long tubes, and the one used to cool the main gasoline

flow has 45 cm long tubes. The heat exchanger in the vent line from

the float bowl assembly to the weigh tank is higher than the weigh tank

and has the vapor from the float bowl assembly entering the 28 straight

tubes at the top so that any condensate will flow into the weigh tank.

A transparent tube connects the heat exchanger to the weigh tank

so that liquid drops can be seen in the tube. A circulator with

a 1/2 horsepower cooler in the next room supplies 15 £/min of

water and ethelene glycol at -15°C for cooling in this heat exchanger.

In-house chilled water at 12°C is used for cooling in the other

two heat exchangers.

An electronic thermometer probe is located in the gasoline line

just upstream of the flowmeter under test, another in the gasoline

line just downstream of the cooling heat exchanger, and a third in the

float bowl vent line between the heat exchanger and the weigh tank,

all as shown in Fig. 3.5. When possible a fourth is located in the

gasoline line just downstream of the flowmeter under test. Because

the probe is inserted into the flow through a T fitting, the fourth

probe can not be installed when the flowmeter manufacturer specifies

mounting the flowmeter as close as possible to the float bowl, e.g. as with the Turbine Flowmeter described in Section II. The probes

each consist of two thermistors inside an 11 cm long 1/8 inch stainless

tube. The probes are inserted through a bored-through 3/8 to 1/8 inch

reducing fitting connected to one run of a 3/8 inch T fitting. The

gasoline flows between the branch of the T and the other run. Thus

- 18 -
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- 19 -
the sensitive end of the probe is well into the flowing gasoline.

The electronic digital displays for these probes are located in the

adjacent room because of the explosion hazard. Reports of test of

the thermometers are reproduced in Appendix H.

A 1 m£-10 m£-100 mJi soap bubble flowmeter is connected to the

weigh tank vent line for use in measuring the flowrate of vapor

displaced by the tank filling plus the flowrate of evaporation of

the gasoline not recondensed. A liquid trap is located in the vent

line between the storage tank and the weigh tank in order to keep

liquid splashing out of the storage tank from entering the vent line

near the weigh tank. This is necessary because the liquid would clog

the soap bubble flowmeter.

An ASTM No. 83-H specific gravity 60°/60°F hydrometer 6 is used

for measuring gasoline density, and a 1/4 size Reid vapor pressure

bomb 7 and two constant temperature baths are used for measuring the

Reid vapor pressure of the gasoline. A T fitting in the fuel line

just downstream of the automotive fuel pump is used for drawing

gasoline from the system for these tests. A valve connected to the

T is opened to fill a container with gasoline and closed during the

flowmeter tests. A similar T fitting in the fuel line just upstream

of the automotive fuel pump is used for returning the gasoline to the

system after the tests are completed. A valve connected to this T is

opened to suck gasoline from the container and closed during the

flowmeter tests.

4. PROCEDURE

4A. Scope.

4A.1 This section describes the procedures for set-up and testing

of the automotive fuel flowmeters.

4B. Summary of Procedure.

4B.1 The flowmeters are mounted securely in the test set-up and

all or some of the tests are performed on them. All data pertinent

to the testing of the flowmeter are recorded: fuel temperature

at the flowmeter, flowmeter indication obtained from flowmeter

display, flowmeter indication obtained by counting flowmeter

output pulses, mass of fuel collected, collection time, specific

gravity of a fuel sample, number of cycles of unsteady flow,

frequency span of vibration, duration of vibration, ratio of actual

flowrate to indicated flowrate, voltage supplied to the flowmeter,

voltage level of superposed sinusoidal signal, repetition rate of

electromagnetic radiation from spark ignition circuit, flowmeter

pressures, fuel pump speed, and temperature and pressure for

determining the Reid Vapor pressure of a fuel sample.

4C. Apparatus.

4C.1 The apparatus used in the tests is described in Section 3.

- 20 -
AD. Preparation for Tests.

4D.1 If vibration tests are to be performed, a substantial

fixture is constructed and used to secure the flowmeter under

test to the armature of the vibration exciter or to the horizontal

slip table. This mounting will also be satisfactory for the

other tests. If no vibration tests are to be performed, a less

massive mounting will suffice. The flowmeter is connected into

the flow system of Fig. 3.1 as described in Section 3. If the

flowmeter to be tested has a bleed outlet, a valve is connected

between it and a transparent return line to the storage tank.

4D.2 All electrical connections are made and tested to insure

proper functioning of the flowmeter and the other apparatus.

The storage tank is emptied and filled with fresh gasoline.

Fuel flow is started, and the system is checked for leakage.

If leaks are found they are repaired. Air bubbles are bled

from the system by momentarily opening the bleed valves until

bubbles no longer are seen in the return lines.

4E. Procedure for Steady Flow Tests.

4E.1 Fuel is withdrawn from the system, its 60/60°F specific

gravity is measured using ASTM Method D287 , and the fuel is

returned to the system.

4E.2 The flowrate is set at one of the seven flowrates: 0.2,

0.5, 1, 2, 5, 10, or 20 g/s, as measured by the transfer standard

flowmeter. The automotive fuel pump is operated at a low speed

that is sufficient to supply the desired flowrate. Five collections

of fuel are made at each of the above flowrates on each of two

days.

4E.2.1 For flowmeters with more than ten output pulses per

gram of fuel metered (100 mg per pulse) the mass collected

is as follows. At the three lowest flowrates, 0.2, 0.5,

and 1 g/s, the mass collected is 200 g. At 2 and 5 g/s it

is 500 g, and at 10 and 20 g/s it is 1 kg.

4E.2.2 For flowmeters with ten or fewer output pulses per

gram of fuel metered, the minimum mass collected must be

larger than 2000 times the mass per pulse except for the

following.

4E.2.3 For flowmeters that indicate in .01 gallon increments,

300 g is collected for . 2 to 2 g/s flowrates, and 3 kg is

collected for 5, 10, and 20 g/s. These flowmeters require

a special procedure that is described in Subsection 4.E.4.

- 21 -
4E.3 Collections of fuel are weighed and timed using the

substitution weighing procedure graphed in Fig. 4.1. For

this procedure the weigh tank is attached to a pan on one

side of an equal arm balance. At the start of a measurement

a (substitution) weight of known mass is placed on the pan.

Sufficient tare weight is on the pan on the other side of

the balance to tilt the second pan down. With the gasoline

flowing through the system in a steady state, the shut-off

valve is closed so that the tank will fill. When sufficient

gasoline is collected to swing the balance arm, it interrupts

a light beam. This starts a timer and two counters that record

the total number of electrical pulses from both the flowmeter

under test and the transfer standard flowmeter. Then the

substitution weight is removed, and the arm swings back. When

sufficient additional gasoline is collected to swing the balance

arm again, it again interrupts the light beam, which stops the

timer and counters. Finally, the shut-off valve is opened

draining the tank, and the substitution weight is replaced.

The average actual flowrate is the substituted mass divided

by the collection time interval.

4E.4 For flowmeters that indicate in .01 gallon increments,

an additional timer is used for obtaining the indicated flowrate.

The closing of the shut off valve in Subsection 5E.3 is timed

so that the collection of the 300 g or 3 kg of gasoline in the

weigh tank starts as nearly as possible to the time a pulse

from the flowmeter starts the timer. The collection will then

end at about the time the tenth or one hundredth subsequent

pulse stops the timer. The output of the transfer standard

flowmeter is plotted as a function of time during the collection

in order to establish that the flowrate is constant. The

indicated flowrate is obtained from the indicated volume and

the time required for it to pass through the flowmeter.

4E.5 The data recorded after each collection of fuel includes:

- substitution mass

- collection time

- flowmeter indication (if available)

- total number of flowmeter output pulses (if available)

- total number of transfer standard flowmeter output pulses

- time required for 10 flowmeter pulses (if flowmeter

indicates in .01 gallon measurements)

- fuel pump speed

- fuel temperature into flowmeter

4E.6 The 60/60°F specific gravity is measured again as in

Subsection 4E.1.

- 22 -
Total Mass

Weighed Mark

Gasoline Filling

Tank Empty

Valve Closed

Valve Opened

Time Interval to be Measured h

rTank Empty

-Weight Replaced

Time

Fig. 4.1. Graph of total mass weighed versus time,

illustrating the substitution weighing procedure.

- 23 -
4E.7 The actual mass flowrate is computed by dividing the substitution mass by the collection time and multiplying the result by

1.0036. As described in Section 5, this factor corrects for the

lost mass of the gasoline vapor that is displaced by the collected

liquid. The "indicated" mass flowrate is computed from the indicated

volume flowrate and the average measured specific gravity using Tables

23, 24, and 26 of Ref. 9. Since the tables include a correction to

give weight as if it were measured in air without a correction for

buoyancy, the result must be multiplied by 1.0017 in order to compare

it with the actual mass flowrate. The ratio of the actual mass flowrate to the indicated mass flowrate is computed for each collection.

This ratio should be equal to one. Both the mean and the relative

standard deviation of the five ratios are computed. The relative

standard deviation or relative repeatibility is the standard deviation

divided by the mean.

4F. Procedure for Unsteady Flow Tests.

4F.1 The 60/60°F specific gravity is measured as in Subsection 4 E.l

.

4F.2 The automotive fuel pump is operated at a low speed that is

sufficient to supply the maximum desired flowrate. The test is

started by setting a steady flowrate of about 10 g/s as measured

by the transfer standard flowmeter.

4F.3 During the collection of a mass of fuel the flowrate is

cycled between and 20 g/s or between 5 and 10 g/s or between

other appropriate rates a number of times and returned to 10 g/s

before the end of the collection time.

4F.4 Five collections are made for each cycled range.

4F.5 The data recorded are the same as in Subsection 4E.5 plus

the following:

- time period over which the flow is cycled

- the number of times the flow is cycled.

4F.6 The 60/60°F specific gravity is measured again as in Subsection

4E.1.

4F.7 The data is analysed as in Subsection 4E.7.

- 24 -
4G. Procedure for Vibrational Tests.

4G.1 The flowmeter or the flowmeter and float bowl assembly

(if the manufacturer specifies attaching one to the other) is

fixtured for either vertical or horizontal vibration.

4G.2 The pulse output of the transfer standard flowmeter is connected

to the A input of an electronic counter, the pulse output of the

flowmeter being tested is connected to the B input, and the counter

is set to count the number of A pulses between one B pulse and the

first, tenth, or one hundredth B pulse that follows. The circuit

used is shown in Fig, 3.3 and described in Sec. 3. The LOG-DC

output of the sweep sine generator is connected to the X inDut of

the XY recorder. This output is a voltage proportional to the

logarithm of the frequency of vibration.

4G.3 The 60/60°F specific gravity is measured as in Subsection 4E.1.

4G.4 The flowrate is set to 10 g/s as measured by the transfer

standard flowmeter. The automotive fuel pump is operated at a low

speed that is sufficient to supply this flowrate.

4G.5 The flowmeter is vibrated through the frequency range of 1

to 1000 Hz . From the low frequency limit to the crossover frequency

the displacement is held constant at 2.5 cm peak-to-peak. From the crossover frequency to the high frequency limit the peak acceleration

is held constant. For most tests the peak acceleration used is

1.5 x 980 cm/s 2

, for which the crossover frequency is 5.4 Hz. If

the flowmeter is to be installed in a location with relatively

little vibration, the peak acceleration used is 0.5 x 980 cm/s , for which the crossover frequency is 3.1 Hz.

4G.6 The XY recorder is used to plot the ratio of the actual to

indicated flowrates versus the logarithm of the frequency of

vibration.

4G.7 The data recorded with the plotted graph are:

- direction of vibration

- peak-to-peak displacement

- crossover frequency

- peak acceleration

- time chosen for the duration of the sweep of the frequency

range

- flowrate indicated by transfer standard meter

- fuel pump speed

- which digits on counter are selected to be plotted

- number of tested flowmeter pulses over which the counter averages

- fuel temperature.

- 25 -
4G.8 If as a result of the test the flowmeter indication is

suspected to be affected by vibration over a portion of the

frequency range, additional shorter frequency range tests are performed over a longer period of time in order to obtain more

precise data describing the effect.

4G.9 Test for effect of increasing acceleration in order to

establish a very small vibration effect.

4G.9.1 The oscillator is set to the frequency at which

the maximum effect on flowmeter indication occurred.

4G.9.2 A DC voltage proportional to peak acceleration is

connected to the X input of the XY recorder.

4G.9.3 The acceleration is increased slowly from zero to

2 x 980 cm/s 2

. 4G.9.4 The XY recorder is used to plot the flowrate ratio

versus peak acceleration.

4G.9.5 The data recorded with the graph are:

- direction of vibration

- frequency

- flowrate indicated by transfer standard flowmeter

- automotive fuel pump speed

- which digits on counter are selected to be plotted

- number of tested flowmeter pulses over which the

counter averages

- time period over which acceleration is increased

- fuel temperature.

4G.10 Test for effect of flowrate on vibration effect.

4G.10.1 The same maximum effect frequency is used.

4G.10.2 The voltage output of the transfer standard flowmeter is connected to the X input of the XY recorder.

4G.10.3 The automotive fuel pump is operated at a low speed

that is sufficient to supply 20 g/s.

4G.10.4 The acceleration is set to 1.5 x 980 cm/s 2. 4G.10.5 The flowrate is increased slowly from zero to 20 g/s.

4G.10.6 The XY recorder is used to plot the flowrate ratio

versus flowrate.

26 -
4G.10.7 The data recorded with the graph are:

- direction of vibration

- frequency

- peak acceleration

- automotive fuel pump speed

- which digits on counter are selected to be plotted

- number of tested flowmeter pulses over which the

counter averages

- time period over which flowrate is increased

- fuel temperature.

4G.11 The vibration tests are repeated for vibration in the other

spatial directions so that tests are completed for vibration in

each of the three perpendicular directions.

4G.12 The 60/60°F specific gravity is measured again as in

Subsection 4E.1.

4G.13 The average fuel density is calculated as in Subsection 4E.7

4H. Procedure for Electrical Tests.

4H.1 The flowrate is set at a steady rate of about 10 g/s.

4H.2 First, with the electrical connections the same as in

Subsection 5G.3, the voltage supplied to the flowmeter under

test is varied from 8 to 16 volts dc. The supplied voltage

is connected to the X axis for the XY recorder, and the indicated

to actual ratio is plotted versus the supply voltage.

4H.3 Second, a 4 volt zero-to-peak 60 Hz sinusoid is superposed

on a fixed 12 volt supply connected to the flowmeter under test.

The difference in flowmeter indication due to the superposed

sinusoid is recorded.

4H.4 Third, a spark ignition circuit is connected to ignition

wire taped to the window, and the circuit is turned on. Both

radio noise suppression ignition wire and insulated metallic

ignition wire are used, first one then the other. The effect

of the spark on the tested flowmeter's indication is recorded

for spark repetition rates up to 240 Hz.

47. Procedure for Variable Pump Speed Test.

41.1 The flowmeters are connected as in Subsection 5G.1 except

that the pump speed is applied to the X input of the XY recorder.

This is done by connecting the magnetic sensor that counts gear

teeth to an electronic counter. The analog output of the counter

is connected to the X input of the XY recorder.

- 27
41.2 With a constant flowrate of about 10 g/s, the automobile

fuel pump speed is varied from 190 to 1900 pulses per minute.

41.3 The XY recorder is used to plot the flowrate ratio versus

pump speed.

41.4 The data recorded with the plotted graph are:

- flowrate indicated by the transfer standard meter

- fuel pressure.

4J. Procedure for High Fuel Temperature Tests.

4J.1 A heat exchanger is connected to heat the fuel upstream of

the flowmeter under test, another heat exchanger to cool the fuel

downstream of the float bowl, another heat exchanger to condense

the vapors vented from the float bowl, and the bubble flowmeter

to measure the vapor flowrate, all connected as shown in Fig. 3.5

and as described in Section 3. The -15°C coolant circulator is

turned on.

4 J. 2 The storage tank is emptied and filled with fresh gasoline.

4J.3 The 60/60°F specific gravity is measured as in Subsection 4E.1.

The Reid vapor pressure is measured using ASTM Method D323.

4J.4 The flowrate is set at 5 g/s, the fuel temperature at the

flowmeter input is set initially at 25°C, and the fuel temperature

upstream of the transfer standard flowmeter is set to room temperature by adjusting the house cooling water flowrate.

4J.5 The tests are conducted in the same manner as in Subsection 4E..

In addition the condensate and vapor temperature is measured. Also

the vent shut off valve must be open whenever the gasoline filling

the weigh tank is about to tilt the balance arm at the beginning

of a collection or at the end. This is necessary so that vapor can pass quickly from the stand pipe into the weigh tank without causing

the oil to gurgle out of the moats. Immediately after the substitution weight is removed, the shut off valve is closed, and the

bubble flowmeter is used to measure the vapor flowrate in the vent

volume line. As soon as this measurement is completed, the vent

shut off valve is opened, in time for the balance to tilt again.

If necessary the vapor flow measurement can be made immediately

following the completion of each collection.

4J.6 Five collections of fuel are made at each temperature.

4 J. 7 The data recorded after each collection are the same as in

Subsection 4E.5 plus the following:

- vapor flow through the bubble flowmeter

- fuel temperature upstream of the constant volume pump

- condensate and vapor temperature.

- 28 -
4J.8 The measurements of Subsection 4 J. 3 are repeated.

4 J. 9 The fuel temperature at the flowmeter under test is increased

by 10°C, the flowrate is reset to 5 g/s, the fuel temperature

upstream of the transfer standard flowmeter is reset to room

temperature, and Steps 4 J. 5 to 4 J. 8 are repeated.

4J.10 Step 4J.9 is repeated until all measurements at 65°C

have been completed.

4J.11 The condensate flowrate is measured as follows when the

fuel at the flowmeter input is at 65 °C. The bleed valve upstream

of the flow adjusting valves is opened, both flow adjusting valves

are closed, and the bleed valve is used to set the gasoline flowrate to 5 g/s. The only flow into the weigh tank will be the

condensate flow. The condensate flowrate is measured by weighing

and timing with a 50g substitution weight. The condensate flow

pulsations are characterized by noting the rate at which drops

pass through the transparent tube from the heat exchanger to the

weigh tank. The mass of the condensate drops can thus be estimated

and used to estimate the error caused by the drops during the

weighing of the main fuel flow.

4J.12 The data is analysed as in Subsection 4E.7 with the following

exception. The vapor mass flowrate is calculated assuming a density

of 2.6 g/£. This mass flowrate is added to the substitution mass

divided by the collection time. The ratio is not multiplied by

1.0036 here because adding the vapor mass flowrate already takes

the buoyancy effect into account.

5. ERROR ANALYSIS

A significant source of error is shown in Fig. 5.1. The mass of liquid

in the falling column is equal to the collected mass times the cross sectional area of the column divided by the cross sectional area of the

weigh tank. The resulting error is not negligible. Also there is another

significant source of error: The force exerted on the liquid in the tank

by the liquid jet is larger at the initial level than at the final level

due to the acceleration of the jet by gravity. Fortunately the difference

between the initial and final force is exactly equal to the weight of the

liquid in the column, and so the two errors cancel exactly. This is true even though the column tapers, becoming smaller in diameter at the bottom

as the fluid speed increases the farther it falls.

Another source of error occurs in correcting for the buoyant force on

the liquid due to the gas in the weigh tank. The density of the liquid

is about .74 g/m£, and the density of air is about 1.2 g/£. Hence, if

the gas were air, the correction would be +.17 percent. However,

because the weigh tank is completely enclosed as described in Section

3, the gas inside eventually becomes just gasoline vapor. The most

volatile component of gasoline is usually butane. The density of

butane at atmospheric pressure and room temperature is about 2.6 g/l . This leads to a correction of about + .36 percent to the mass collected.

Since the tables used for density are for weighings in air, a correction

- 29 -
Final Level —

Initial Level

Fuel to be Weighed

\/

This Column of

Liquid is Collected

But Did Not Come

Out of the Nozzle

During the Timing

Interval

Weigh Tank

Fig. 5.1. Error due to the additional fuel collected.

- 30 -
equal to the difference (.36 - .17 = .19 percent) is applied to the

data. The buoyant force of air on the brass weights used for substitution weighing is negligible.

Butane is not the only component of gasoline that evaporates. Gasoline

is a mixture of a number of components with different boiling points

and densities (and viscosities). As time passes, or as the temperature

is raised, other of the more volatile components will also escape or

be driven off. As a result the properties of the gasoline will change.

Hence the .19 percent correction is only approximately correct, and the

uncertainty is probably within the precision of the test system.

The precision of the flowrate calibration can be estimated as follows.

The sensitivity of the balance is better than 0.1 gram, and the smallest

mass collected is 200 grams (for the three lowest flowrates) . This

gives a readibility of .05 percent for each calibration at the lowest

flowrates.

Note that the substitution weighing procedure eliminates any error

due to the inertia being different at the two marks. This error occurs with the alternative procedure where the weight is placed on the

counter balance pan after the collection is started rather than being

removed from the weigh tank pan at that time as in the substitution

procedure. In the first case the moment of inertia of the balance

arm, weights, pans, and weigh tank is larger at the full tank mark

than it is at the empty tank mark. Since the rate of change in torque

due to the gasoline entering the tank is the same at both marks, the

rotational acceleration of the balance arm would be less at the full

tank mark than at the empty tank mark. However, this effect would be

small for the present system because of the low flowrates involved.

Although enclosing the weigh tank with vapor seals reduces one source of error, it can introduce another if the vent lines are small.

When the balance arm swings, the vapor volume inside the tank is

suddenly increased by a small amount equal to the area of the inverted

cup multiplied by the vertical distance the tank moves. This volume

of vapor must pass quickly through the vent line in order to prevent

distortion of the liquid level in the oil moat. If the vent lines

are not sufficiently large the pressure inside the tank will decrease

enough to cause a substantial force on the balance arm. At the lower

seal a similar effect occurs but in the opposite direction. Unfortunately the forces do not cancel because they depend upon the vapor

volume in each closed region, and these are not equal. For the same reason the effect is different when the tank is full and when it is

empty. With the vent lines used at first this caused a small difference in the response time of the balance arm at the upper and lower

fill marks. To minimize this effect the vent lines were increased

from 4 mm to 7 mm inside diameter.

31 -
A measurement was made of the effectiveness of the 7 mm vent line,

which was approximately 1 meter long between the weigh tank and the

storage tank. The flowrate was set at 20 g/'

, and weights were

chosen so that the vapor volumes at the lower and upper marks were

3.9£ and 0.5£, respectively. The ratio of these volumes is much

larger than the ratio for the upper and lower marks used when

calibrating flowmeters so the measurement reliably establishes an upper limit for the error. The resulting response is seen in

Fig 6.2 to be sufficiently similar at the two marks to result in

a negligible error since the shortest collection time was 50 seconds.

Another potential source of error arises from evaporation of the

gasoline from the float bowl and the weigh tank. At room temperature

the error is negligible since after the system reaches a steady state

the enclosed space over the liquid is filled with gasoline vapor,

which tends to reduce further evaporation, and since the collection

time does not exceed 1000 seconds. At higher temperatures the

evaporation from the float bowl increases. Much of this vapor is

condensed by the heat exchanger in the float bowl vent line, and the

resulting condensate drips into the weigh tank and gets weighed. The

flowrate of the vapor that is not condensed plus the vapor displaced

by the liquid filling the weigh tank is measured by the bubble flowmeter. For a float bowl temperature near 65 °C the net vapor flowrate

measured is about 12 m£/s for gasoline with a Reid vapor pressure of

about 8.9 psi. If the measured vapor density is assumed to be about

2.6 g/l, the vapor mass flowrate is about .03 g/s. Because the

composition of the vapor and hence its density is not certain, the

vapor mass flowrate is uncertain by about .01 g/s. This leads to an uncertainty of .2 percent in the 5 g/s liquid flowrate measured

at 65°C.

The uncertainty caused by the condensate dripping into the weigh tank

rather than flowing smoothly can be estimated as follows. For a float

bowl temperature near 65 °C and a Reid vapor pressure of about 8.9 psi,

the condensate flowrate is about .2 g/s. The condensate pulses through

the transparent tube to the weigh tank about once a second. Hence,

the condensate drops that fall into the weigh tank in one burst have

a total mass of about .2 g, and so the uncertainty in the mass collected

caused by the dripping is about .2g. For a substitution mass of 500 g,

the resulting readibility for each flowrate measurement is .04 percent.

5A Summary of Potential Errors

Three kinds of errors have been discussed: 1) errors that exactly cancel

other errors, 2) errors that are negligible for the conditions of the

tests, and 3) errors that although they are quite small are not definitely

negligible and whose magnitude is uncertain and cannot be corrected.

- 32 -
V

10

C3<

o 5

. . . .

'

25

TIME

50 ms

Fig. 5.2. Response of the beam balance with the weigh tank nearly

empty and again with the tank full. The vertical axis is the output

of the photo-Darlington, which is normally used to start and stop

counters when the balance arm swings. The 60 Hz ripple just visible

on these curves was not eliminated because it leads to a negligble

error since the shortest collection time is 50 seconds.

- 33 -
Errors of the first kind are: some of the liquid collected did not come out of the nozzle during the timing interval, the force exerted

by the jet is different at the initial and final levels, and the inertia

of the balance system could be different at the two levels.

Errors of the second kind are due to: the buoyant force of air on brass weights, the sensitivity of the balance system, the number of

flowmeter output pulses per gram of fuel metered as described in

Sec. 5E.2, the difference in response of the balance arm at the two

levels because of the finite size of the vent line between the weigh

tank and the stand pipe, and the magnitude of the condensate pulses.

The error of the third kind is due to not knowing the mass flowrate

of the vapor leaving the float bowl and weigh tank. This arises because

of inaccuracy in the volume flowrate measurement and because of a lack

of knowledge of the vapor density. At low temperatures the volume flowrate of the vapor is probably equal to the volume flowrate of the liquids,

But the vapor density remains unknown for converting the volume flowrate to mass flowrate or equivalently for making the buoyancy correction.

6. TEST RESULTS

Results of tests on seven flowmeters are presented in order to illustrate

the use of the procedure of Sec 4. It should be emphasized that only

one of each of the seven kinds of flowmeters was tested. Hence the

results may not reliably indicate how other flowmeters made by the same manufacturer will perform. Also, a complete series of tests to determine

flowmeter performance has not been carried out. Some of the tests have

been performed on only one flowmeter. Hence the present test results

should not be used as an indication of how a given flowmeter would

perform in an automobile on the road.

In the following graphs of the flowmeter calibration curves, each data

point is the average of five collections, and the vertical bar shows

plus and minus one standard deviation from these five collections. The

actual flowrates for the different day points are: 0.2, 0.5, 1, 2, 5,

10, or 20 g/s. However, in order to avoid superposing data points for

the two successive days, the two points are displaced slightly from the

above values, with the first day's data point shifted slightly to the

left and the second slightly to the right.

6A. Four Orifice Flowmeter

The first meter calibrated is described in Appendix A. It was tested

in a set-up similar to Fig. 3.5. and connected into the fuel line in

the place labeled "transfer standard meter." The vapor flowmeter, the

automotive fuel pump, the float bowl assembly, and the "meter under

test" that are shown in Fig. 3.5 were not in the flow loop.

- 34 -
The particular meter tested gave an 11.5 percent error when first

calibrated because its voltage output had too high an impendance for

the 100 kfi input impedance of the voltage-to-frequency converter (VFC)

used. This 100 kfi input impedance is typical for VFCs and should

have been anticipated in the design of the flowmeter. In order to

eliminate the change in flowmeter calibration factor when a VFC is

connected, the electronic circuit of the flowmeter was redesigned

lowering its output impedance, a VFC was permanently connected, and

the span and linearity were readjusted.

The calibration curve for the modified flowmeter is shown in Fig. 6A.1

with the data given in Table 6A.1. The results of unsteady flow tests

for the flowmeter are given in Table 6A.2. Even though this flowmeter

is not perfect, it is useful as a transfer standard for testing other

flowmeters because it gives one pulse for each milligram of gasoline

passing through it. Its calibration was rechecked when it was used

in the evaluation of the other flowmeters, and the results were consistent

with the data reported here.

- 35 -
<

cc

<

o

<

<

1.02 I t— 1 1 1 1 1 —

o On

>

ONE STANDARD DEVIATION

1.01 — J —

§

2S

I o 5

X A

1.00

I

) :

5

£ H. To

2

§

.99

i [ I

1 1 i

1 1 1

—

1 2 5 ACTUAL FLOWRATE10 20 g/s

Fig. 6A.1. Four Orifice Flowmeter calibration curve. The actual flowrate

is obtained by weighing and timing. The circles indicate data taken at

20°C, the x's at 30°C, and the triangles at 40°C. The actual flowrates

are nominally 0.2, 0.5, 1, 2, 5, 10, and 20 g/s, and the points on the

graph are slightly displaced horizontally from these values only to

avoid overlapping them.

- 36
Table 6A.1

Four Orlf:Lee Flowmeter

St eady Flow Test

Actual Indicated Meter Relative

Flowrate Flowrate Factor* Repeatabil ity**

(r/s) (R/s)

0.199

(Ideally = 1)

1.0169

(Percent)

0.202 0.34

0.515 0.507 1.0148 0.48

1.015 1.010 1.0055 0.07

2.008 2.004 1.0014 0.02

5.057 5.060 0.9993 0.05

9.981 10.035 0.9946 0.28

9.995 10.006 0.9989 0.16

19.84 19.95 0.9943 0.04

19.97 19.98 0.9998 0.11

Average Temperature - 20°C

0.199 0.199

0.498 0.501

0.998 1.000

1.999 2.001

4.991 4.997

10.01 9.998

19.97 19.99

19.98 20.00

1.0023 0.10

0.9958 0.10

0.9978 0.18

0.9990 0.03

0.9988 0.07

1.0016 0.04

0.9988 0.08

0.9991 0.03

0.198 0.200

0.495 0.500

0.994 0.999

1.998 1.998

5.014 5.001

5.014 4.999

10.05 9.996

20.05 19.99

Average Temperature - 30 °C

0.9891 0.33

0.9914 0.15

0.9949 0.14

0.9995 0.02

1.0023 0.02

1.0029 0.06

1.0055 0.03

1.0027 0.23

Average Temperature - 40°C

* Actual flowrate divided by flowmeter indication, averaged over five

measurements at each flowrate.

** Standard deviation of the five flowrate ratios divided by the mean

of the ratios.

- 37 -
Table 6A.2

Four Orifice Flowmeter

Unsteady Flow Test

Number of Period of Cycled Average Meter Relative

Flowrate Cycle Flow range Flowrate Factor* Repeatability**

Cycles (seconds)

13

(g/s) (g/s)

7.6

(Ideally = 1)

1.0007

(Percent)

10 5-10 0.01

5 25 0-20 8.0 1.0189 4.45

5 24 6.5-9.9 8.3 1.0010 0.02

5 22 1-20 8.9 1.0028 0.95

5 18 4-20 11.1 0.9992 0.11

3 26 0-20 11.5 1.0004 0,03

3 26 0-20 12.94 1.0035 0.03

4 21 0-20 12.14 1.0020 0.17

5 18 0-20 10.90 1.0018 0.02

* Actual flowrate divided by the meter indication, averaged over five measurements at each flowrate.

** Standard deviation of the five ratios of actual to indicated

flowrate divided by the mean of the ratios.

38 -
6B Four Piston Flowmeter

This flowmeter is described in Appendix B. Its calibration curve is

shown in Fig. 6B.1 with the data given in Table 6B.1. The indicated

flowrate for the calibration was obtained from a digital readout,

which gives total flow in 1 ml increments and total time in 1 s increments,

Table 6B.1

Four Piston Flowmeter

Steady Flow Test

Actual Indicated Meter Relative

Flowrate Flowrate Factor* Repeatability**

(mis) (ml/s)

First

(Ideally = 1)

Day

(Percent)

0.2652 0.2640 1.0047 0.15

0.6624 0.6596 1.0043 0.18

1.338 1.331 1.0049 0.11

2.663 2.656 1.0029 0.03

6.550 6.631 1.0028 0.13

.3.35 13.32 1.0015 0.02

6.34 26.28 1.0022 0.15

0.2730 0.2708 1.0081

0.6761 0.6726 1.0051

1.373 1.363 1.0069

2.750 2.740 1.0040

6.872 6.846 1.0037

13.73 13.69 1.0027

27.37 27.30 1.0026

Average Temperature = 26°C, Average Density = 0.7501 g/m£

Second Day

0.27

0.38

0.06

0.07

0.11

0.06

0.13

Average Temperature 26°C, Average Density = 0.7277 g/m£

* Conversion factor times the actual flowrate divided by the meter

indication, averaged over five measurements at each flowrate.

** Standard deviation of the fire ratios of actual to indicated

flowrates divided by the mean of the ratios.

Some of the scatter in the data can be understood as follows. The

displayed total flow for this flowmeter increases by 1 mil for each

pulse from the flowmetering element except that occasionally the display

increases by 2 ml in the normal operation of the flowmeter. This occurs because the volume per pulse from the flowmetering element is

not exactly 1 m£ , and the electronic circuit in the display unit corrects

for this by occasionally increasing the display by 2 ml instead of 1 ml.

For the particular flowmeter tested, the display always skips the values

shown in Table 6B.2.

- 39 -
<

cco

Q

O

Q

1.010

1.008

< 1.004H-

< 1.002 —

<

1.000 —

ONE STANDARD DEVIATION

I

I

1

1 2 5 ACTUAL FL0WRATE

10 20 g/s

Fig. 6B.1. Four Piston Flowmeter calibration curve. The circles are

for data taken on the first day of testing, and the x's the second day.

The actual flowrates are nominally 0.2, 0.5, 1, 2, 5, 10, and 20 g/s,

and the points on the graph are displaced from these values only to

keep the data points and flags from overlapping.

- 40 -
Table 6B.2

Four Piston Flowmeter

Display Values, (ml) Skipped Differences

15

15

15

15

15

15

16

15 122 229 336

30 137 244 351

45 152 259 366

61 168 275 382

76 183 290 387

91 198 305 412

106 213 320 427

107

It is apparent that the pattern repeats every 107 ml and so the table

has not been continued past 427 ml. It follows that on the average

the calibration of this flowmeter is approximately 1.07 ml per pulse

from the flowmetering element. One can also see that due to the

occasional skipping the displayed total flow can be too small by as much as .99 ml.

In addition there is another noncumulative error that occurs with this

flowmeter. The flowmeter calibration differs slightly from pulse to

pulse because the 10 pulses that occur in one revolution of the crank

do not correspond to equal displacements. The volumes for the first

five pulses are 1.10 ml, 1.10 mil, 0.91 mA, 1.09 mi, and 1.16 ml, and

the second five pulses repeat this pattern. Thus, one time out of five,

as much as 1.15 ml can flow before the next pulse comes. The sum of

these two errors can make the total flow displayed by this flowmeter too

small by as much as 0.99 ml + 1.15 ml = 2.14 m£ even if the flowmetering

element were perfectly accurate. This contributed to the scatter in

Fig. 6B.1.

Note that another flowmetering element made by the same manufacturer

could have a calibration less accurate than this one. It could be off

as much as 1/2 percent because the volume per pulse could be as large

as 1.075 ml and the nominal calibration would still be 1.07 m£ . Only

if the volume per pulse were larger than 1.075 ml would the nominal

calibration of the readout be changed to 1.08 ml.

The flowmeter evaluated has no pulse output for use in the other tests

described previously. So its cover was removed, and pulses were taken

from a convenient point at the input of the readout circuit. Some

results of vibrating this flowmeter and using the technique described

previously are shown in Figs. 6B.2 to 6B.5, which show an error that occurs at a frequency near 16 Hz. The factor 1.07 appears in the

ordinate because the flowmeter gives a pulse for each 1.07 ml. The

meter factor is averaged over a multiple of 10 pulses in order to smooth

out the differences in the volume per pulse described previously. The

last graph shows an immense error at low flowrates.

- 41 -
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... —±E I'll ,:,; : ti 1 10 100 1000»Hz FREQUENCY

Fig. 6B.2. Vertical vibration test of the Four Piston Flowmeter. The

peak-to-peak displacement is 2.54 cm from 1 to 5.4 Hz, and the peak

acceleration is 1.5 x 980 cm/s 2 from 5.4 to 1000 Hz. The time required

for sweeping from 1 to 1000 Hz is 10 minutes. The flowrate ratio times

1.07 is averaged over 107 m£ . The factor 1.07 occurs because the

flowmeter on the average has one pulse per 1.07 m£ indicated on its

digital display, and the pulses are used to obtain the vertical display.

The actual flowrate is 10 g/s, the indicated flowrate is in mJi/s, and

the average density is .73 g/m£, so the ordinate should be .78 g/m£.

- 42 -
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.

i i 14 15 16 17 18 19 Hz FREQUENCY

Fig. 6B.3. Vertical vibration test of Four Piston Flowmeter. The

conditions are the same as in Fig. 6B.2 except the frequency is swept

from 14 to 19 Hz in 10 minutes, and the ratio times 1.07 is averaged

over 10.7 m£. The effect is more clearly shown here than in Fig. 6B.2.

- 43 -
<3o_iU_QLLI I-<o

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1^o

lijo i.i if:.; fj

; lli 'i ii ijiLEI. ill; up - :- m m1.4 ACCELERATION

2.2 x980 cm/s2

Fig. 6B.4. Vertical vibration test of Four Piston Flowmeter. The

conditions are the same as in Fig. 6B.3 except the frequency is fixed

at 16.1 Hz and the peak acceleration is increased smoothly over a 10

minute interval. The wide excursions in the graph above 2 x 980 cm/s 2 are due to the ratio exceeding the maximum range of the digital to

analog converter. Below 2 x 980 cm/s2 the effect is clearly shown

to increase with increasing acceleration.

- 44 -
g/ml

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4 8 12 16 2(0g/s

ACTUAL FLOWRATE

Fig. 6B.5. Horizontal vibration test of Four Piston Flowmeter. The

conditions are similar to those in Fig. 6B.3 except the frequency is

fixed at 16.0 Hz and the flowrate is increased smoothly over a 20 minute

interval.

- 45 -
However, the error shown in these figures was not observed on the

digital display because the readout electronics incorporated an up-down counter. The display was observed to count up and down

between adjacent values many times before advancing permanently to

the next value. Thus the error did not accumulate, and this was confirmed by comparing the indicated flowrate obtained from the

digital display with the actual flowrate from weighing and timing.

Otber tests were made on this flowmeter. The input voltage was varied

from 8 V to 16 V. An 8 V peak-to-peak 60 Hz sinusoidal voltage was added to a constant 12 V. Also, 1 V rectangular pulses were added

to a constant 12 V. None of these caused the flowmeter to make an

error. But when a spark was discharged within several meters of the

flowmeter (with its cover on), an essentially infinite error occurred.

Fortunately, when resistive ignition wire is used instead of solid

wire, no noticable error occurred.

6C Positive Displacement Pump Flowmeter

This flowmeter is described in Appendix C. The flowmeter has both

an electrical pulse output and an electromagnetic counter built

into it. The built in counter was started and stopped manually

at the beginning and end of a collection. Because of this the two

indications agree only approximately with each other. The calibration

data for the pulse output is given in Table 6C.1, and the calibration

curve for the built-in counter is shown in Fig. 6C.1. The collections

that gave rise to the large scatter in both of these at 20 g/s were

taken at the beginning of the second day. The first two collections

gave results that agreed with the previous day's results. The last

three at that flowrate gave much higher indications. During these

three collections the flowmeter made slightly more noise then it had

before. When the flowrate was decreased to 10 g/s for the next set,

the noise went away, and all results .from subsequent collections that

day agreed with the results of the previous day as shown. However,

on occasion on subsequent days the flowmeter was similarly erratic

at 20 g/s and also at other flowrates. The cause for the erratic

readings and for the associated increase in noise has not been determined,

46
1.08-

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<ccp 1 nn —

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1.00

1 2 5 ACTUAL FLOWRATE

20 g/s

Fig. 6C.1. Calibration curve for the Positive Displacement Pump Flowmeter

The indicated flowrate is obtained from the counter supplied with the

flowmeter. Similar but not identical results were obtained from the

electrical pulse output and are reported in Table 6C.1. The flowrate

ratio should be equal to one. The large scatter at 20 g/s on the second

day is due to the flowmeter and is discussed in the text.

47 -
Table 6C.1

Positive Displacement Pump Flowmeter

(Pulse Output)

Steady Flow Test

Actual Neter Meter Relative

Flowrate Indication Factor* Repeatability**

(m£/s) (m£/s) (Ideally =

First Day

1) (Percent)

0.2700 0.2534 1.0653 1.41

0.6777 0.6542 1.0359 0.38

1.363 1.326 1.0273 0.13

2.733 2.673 1.0223 0.20

6.858 6.704 1.0229 0.14

13.71 13.35 1.0273 0.03

27.30 26.38 1.0349 0.61

Secon d Day

0.2684 0.2541 1.0561

0.6835 0.6577 1.0392

1.363 1.330 1.0264

2.730 2.665 1.0245

6.857 6.695 1.0242

13.72 13.26 1.0343

27.32 27.39 0.9974

Average Temperature = 2.6°C, Average Density = 0.7308 g/m£

0.61

0.29

0.72

0.26

0.9

0.09

4.08

Average Temperature = 26°C, Average Density = 0.7305 g/m£

The effect of supply voltage on the pulse output on two separate days

is given in Table 6C.2, and the effect of supply voltage on both outputs

is compared in Fig. 6C.2. Vibration and other tests on this meter were difficult to analyze because of the erratic output shown in Figs. 6C.3

and 6C.4. This erratic output seemed to occur at all times and appears

to be unrelated to that shown in Table 6C.1 and Fig. 6C.1. Because of

the erratic behavior, no further tests were made on this meter.

- 48
Table 6C.2

Positive Displacement Pump Flowmeter

(Pulse Output)

Supply Voltage Test

Supply Meter Relative

Voltage Factor58 Repeatability**

(Volts DC) (Ideally=l)

First Day

(Percent)

9.6 1.0292 0.27

11.9 1.0425 0.14

14.1 1.0392 0.29

16.4 1.0426 0.06

Second Day

9.5 1.0294 0.19

11.8 1.044 0.09

14.0 1.0314 0.10

16.4 1.0446 0.06

Average Temperature = 28°C, Average Density = 0.7444 g/m£

Actual Flowrate = 10 g/s

* Conversion factor times the actual flowrate divided by the meter

indication, averaged over five measurements at each flowrate. The

conversion factor includes the manufacturer's recommended

calibration of 12,000 pulses per gallon.

** Standard deviation of the five ratios of actual to indicated flowrates divided by the mean of the ratios.

- 49 -
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1 1

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1.03 t

} ONE STANDARD DEVIATION

* —

1.02 < >

1.01 — -

1 00 I I i i 10 12 14 16

VOLTAGE

Fig. 6C.2. Effect of supply voltage on the Positive Displacement Pump

Flowmeter with an actual flowrate of 10 g/s. The solid circles are from the flowmeter's built-in counter and the x's are from the pulse

output at 1/12000 gallon per pulse. For both sets of data the flowrate

ratio should be equal to one.

- 50 -
240 r

<cco_lu_QLUI—<o

o

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<

60 s

Fig. 6C.3. Erratic pulse output of the Positive Displacement Pump

Flowmeter. The actual flowrate is 10 g/s, and the flowrate ratio is

averaged over 10 pulses of the flowmeter under test.

- 51 -
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100 200 300

TIME

400 500 600 s

Fig. 6C.4. Erratic pulse output of the Positive Displacement Pump

Flowmeter. The conditions are the same as for Fig. 6C.3 except that

100 pulses are averaged. A substantial improvement results, but the

averaged output is still not usable.

- 52 -
6D TURBINE FLOWMETER

This flowmeter is described in Appendix D. In accordance with the

manufacturer's recommendation, it was connected to the fuel line

as close as possible to the float bowl. The automobile fuel pump

was operated at 320 pulses per minute for all tests except one in

which the pump speed was varied.

The flowmeter calibration curve is graphed in Fig. 6D.1 using the

steady flow data in Table 6D.1, and the unsteady flow test results

are in Table 6D.2. Even though .2 g/s and .5 g/s are below the

manufacturer's recommended range, measurements were taken at these

flowrates because some automobiles sometimes use fuel at these flowrates.

Even though the pulse output of this flowmeter is erratic as shown

in Fig. 6D.2, vibration tests were performed. In these tests the

float bowl assembly was vibrated along with the flowmeter. The results

are shown in Figs. 6D.3 to 6D.5.

The erratic pulse output of the flowmeter also made it difficult to

detect small effects in the electrical tests. The input voltage was

varied from 8 to 16 V. Also an 8V peak-to-peak 60 Hz sinusoidal

voltage was added to a constant 12V supply. These did not cause the

flowmeter to make an observable error. The results of the ignition

radiation tests are given in Table 6D.3.

For the high fuel temperature tests a .04" bit was used to drill a vapor return hole in a port at the top of the flowmeter as recommended

by the manufacturer. At 25°C the vapor return bypass line was entirely

full of liquid. As the temperature increased more and more vapor

bubbles appeared in the bypass line, and at 45°C and higher the bypass

line was entirely full of vapor.

Also at 42°C, condensate could just be seen to flow from the bottom

of the heat exchanger installed in trie float bowl vent line. The

condensate flow pulsed through the transparent tubing and into the

weigh tank about once every second. The condensate flow increased

with temperature to about .2 g/s at 65°C.

At about 52 °C the liquid in the float bowl had an abundance of bubbles

as if it were boiling even though the float bowl was heated only by

the gasoline entering it. The space over the liquid was filled with

a fog, and droplets formed on the plexiglass window and ran down it.

The high fuel temperature tests are reported in Table 6D.4. The Reid

vapor pressure measurements were made just after the five weighing

and timing collections were made. The sharp decrease in the meter

factor and increase in the repeatibility at 55°C and 65°C are apparently

due to vapor bubbles in the liquid flow measured by the Turbine Flowmeter.

The vapor return hole was not large enough to remove all of the vapor

bubbles from the flow.

- 53 -
2.0

I III

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cc5 I —

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ACTUAL FLOWRATE

10 20 g/s

Fig. 6D.1. Turbine Flowmeter calibration curve. The average fuel

density is .758 g/m£ , and the manufacturer's recommended conversion

factor is 7200 pulses per gallon. These were used to obtain the

flowrate ratio, which should be equal to one.

- 54 -
Table 6D.1

Turbine Flowmeter

Steady Flow Test

Actual

Flowrate

(ml/s)

0.270

0.65

1.31

2.64

6.62

13.1

26.4

0.265

0.657

1.31

2.63

6.57

13.2

26.3

Pulse Meter

Repetition Factor*

Rate (Hz) (Ideally=l)

First Day

2.77 1.8490

10.9 1.1523

24.5 1.0221

50.0 1.0050

125. 1.0044

256. 0.9865

508. 0.9894

Second Day

2.90 1.7464

10.6 1.1791

25.0 1.9992

50.0 1.0044

125. 1.0000

258. 0.9719

507. 0.9872

Relative

Repeatability**

(Percent)

4.13

0.54

0.37

0.13

0.08

0.19

0.14

3.72

1.83

0.11

0.27

0.08

0.63

0.05

Average Temperature = 24°C, Average Density = 0.7580 g/m£

Table 6D.2

Turbine Flowmeter

Unsteady Flow Test

Number of Period of Average Meter Relative

Flowrate Cycle Flow Range Flowrate Factor* Repeatability**

Cycles (Seconds)

25

(ml/s)

- 26

(ml/s)

10.5

(Ideally=l)

0.9663

(Percent)

5 0.37

5 22 1.3 - 26 11.7 0.9590 0.44

5 18 5.3 - 26 14.6 0.9657 0.36

10 13 6.6 - 13 9.98 0.9914 0.17

5 24 8.6 - 12 10.9 0.9794 0.10

4 17 13 - 26 19.0 0.9766 0.67

Average Temperature = 24°C, Average Density = 0.7599 g/m£

- 55
Table 6D.3

Turbine Flowmeter

Ignition Radiation Test

Spark Actual Pulses Indicated

Frequency Flowrate Repetition Flowrate

(Hz) (mH/s) Rate (Hz)

Solid Ignition Wire

(m£/s)

13.8 280 14.5

33 13.8 500 540.

100 13.8 1290 407.

250 13.8 2250 573.

365 13.8 2750

Resistive Ignition Wire

68.7

13.7 270 14.5

32 13.7 278 13.9

101 13.7 276 14.5

252 13.7 283 14.5

380 13.7 290 14.5

Average Temperature = 23°C

56
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1 07 '

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| 100 200 300 400 500 600 s TIME

Fig. 6D.2. Erratic pulse output of the Turbine Flowmeter. The

actual flowrate is 10 g/s, and the flowrate ratio is averaged over 1000 pulses of the Turbine Flowmeter.

- 57 -
<cc

oLU

I—<o

<

CC

<

1000 Hz FREQUENCY

Fig. 6D.3. Vertical vibration test of the Turbine Flowmeter. The

actual flowrate is 10 g/s, and the flowrate ratio is averaged over

1000 pulses. The peak-to-peak displacement is 2.54 cm from 1 to

5.4 Hz, and the peak acceleration is 1.5 x 980 cm/s 2 from 5.4 to

1000 Hz. The time required for sweeping from 1 to 1000 Hz is 30

minutes, and the average density is .76 g/mJl.

- 58 -
FREQUENCY

100 1000 Hz

Fig. 6D.4. Effect of vibrating the Turbine Flowmeter horizontally

and perpendicular to the flow direction. Other conditions are the

same as in Fig. 7D.3 except the sweep time is 10 minutes.

- 59 -
10 100

FREQUENCY

1000 Hz

Fig. 6D.5. Effect of vibrating the Turbine Flowmeter horizontally

and parallel to the flow direction. Other conditions are the same

as in Fig. 6D.4.

- 60 -
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H - 61 -
That the meter factor at 65°C is larger than the one at 55°C can be

explained as follows. The test at 65 °C was performed on October 22

using regular gasoline purchased on October 21. The gasoline was heated to 45°C on October 21 and permitted to cool. It was heated

to 65 °C on October 22 for several hours before the measurements were

made. On the other hand the tests at 45°C and 55°C were made on October 27 using gasoline purchased that day. After the test at

45°C was completed the gasoline was heated to 55 °C, and the test at

55°C was performed without delay. The explaination is that the rate

of evaporation from gasoline that has been at 65 °C for several hours

is lower than the rate from gasoline that was just raised to 55°C.

Thus more vapor was in the gasoline metered at 55°C than that at 65°C,

and this explains the difference in meter factors.

6E Automatic Burrette Flowmeter

This flowmeter is described in Appendix E. Since each flowmeter pulse

indicates .01 gallon (38 m£) a huge error would occur if the indicated

flowrate were obtained by counting the flowmeter pulses that occur while

only 200 g (270 m£ at . 74g/m£) is weighed and timed. Hence the procedure

of Subsection 4E must be modified.

The easiest way to do this involves the assumption that once the system

has settled to a steady flow, the flowrate will remain constant long

enough for about .1 gallon to flow. The indicated flowrate is obtained

from the time for ten periods (or the time interval between a pulse and

the tenth one following it) and is converted to mass flowrate as in

Subsection 5E.7. The actual flowrate is obtained by timing the weighing

of 300 g of fuel at about the same time the .1 gallon passes through

the Automatic Burrette Flowmeter and is corrected as in Subsection 5E.7.

The first Automatic Burrette Flowmeter that was tested did not permit

a flowrate above 6 g/s. The manufacturer replaced it with one that

permitted a flowrate of 12 g/s and that also was modified to reduce its

sensitivity to vibration. The flowmeter performed satisfactorily for

a while, but then started to leak profusely. On the recommendation of

the manufacturer an attempt was made to seal the leak with epoxy. It was not successful, and so the tests were halted. The data that was obtained in the few measurements that were performed is not presented

here because the flowmeter failure prevented confirmation of some questionable results.

6F Ball-in-Race Flowmeter

This flowmeter is described in Appendix F. The first Ball-in-Race

Flowmeter that was tried gave no indication of flow and was replaced

by the manufacturer. The flowmeter that was tested was inserted in

the fuel line just upstream of the float bowl. The flowmeter was mounted so that the fuel flow into and out of it was horizontal, and

the ball inside it travelled in a vertical plane. The automotive fuel

pump was operated at 312 strokes per minute.

- 62 -
The results of the steady flow tests are given in Table 6F.1 and

graphed in Fig. 6F.1. The data was obtained from the electrical

pulse output. The counter supplied with the flowmeter was reset

manually as quickly as possible at the start of a collection and

read immediately at the end. The reading was always within one

count of the total number of pulses divided by 32. The maximum

possible flowrate was 15.6 g/s, while the advertised range was .5

to 20 gallons per hour (.5 to 21 mifs) , which is equivalent to .4

to 16 g/s. The mass collected was 3 kg for all flowrates except

that it was 1 kg for 1 g/s and on the second day it was 2 kg for

2 g/s. At .5 g/s the flowmeter indication was incorrect by a factor about 10 and so data was not taken below 1 g/s.

The large scatter in the data at 2 g/s and the large difference in

means at 5 g/s may be attributed to the flowmeter tested. The

scatter and difference occurred because the time required for one gallon to be indicated by the flowmeter showed a similar scatter

and difference. There was not an appreciable change in the density,

temperature, or flowrate, and there were no bubbles in the fuel as

is apparent from the following. At 2 g/s on the first day, the. relative repeatibility of the actual flowrate was .20 percent, and

that of the transfer standard flowmeter's indicated total mass was

.03 percent. At 5 g/s the mean actual flowrate differed by .07

percent from day to day, and the mean indication of the transfer

standard flowmeter differed by .04 percent from day to day.

Table 6F.1

Ball-in-Race Flowmeter

Steady Flow Test

Actual Flowmeter Meter Relative

Flowrate Indication Factor* Rep eatability**

(mX/s) (GPH) (Ideally=l)

First Day

(percent)

1.35 0.96 1.192 0.28

2.70 2.25 1.023 12.8

6.75 6.29 0.909 0.24

13.5 11.1 1.028 0.49

21.0 16.9 1.057 0.30

- 63 -
Actual Flowmeter Meter Relative

Flowrate Indication Factor* Repeatability**

(m£/s) (GPH)

Second

(Ideally = 1)

Day

(percent)

1.35 0.95 1.198 0.45

2.70 1.97 1.157 0.05

6.75 5.33 1.078 0.14

13.5 10.8 1.060 0.05

21.0 17.1 1.039 0.25

Average Temperature = 23°C, Average Density = 0.7423 g/m£

*Conversion factor times the actual flowrate divided by the indicated

flowrate, averaged over five measurements at each flowrate. The

conversion factor includes the manufacturer's recommended calibration

of 3200 pulses per gallon.

**Standard deviation of the five ratios of actual to indicated flowrates

divided by the mean of the ratios.

The flowmeter and float bowl assembly were vibrated together, and the

results are shown in Figs. 6F.2 and 6F.3. The effect of ignition

radiation on the indication of the counter supplied by the flowmeter

manufacturer is shown in Table 6F.2.

Table 6F.2

Spark

Repetition

Rate (Hz)

Ball-in-Race Flowmeter

Ignition Radiation Test

Actual

Flowrate

(m&/s)

Indicated

Flowrate

(m£/s)

Solid Ignition Wire

13.2 12.0

33 13.2 16.4

118 13.2 21.4

318 13.2 34.7

338 13.2

Resistive Ignition Wire

Erratic

33 13.2 12.0

99 13.2 12.0

215 13.2 12.0

328 13.2 12.0

64 -
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o

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.y

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.2 2 5 ACTUAL FLOWRATE

10 15.6 g/s

Fig. 6F.1. Ball-in-Race Flowmeter calibration curve. The circles are

for data taken on the first day of testing, and the x's the second day.

The omission of data at low and high flowrates, the large scatter at

2 g/s, and the discrepancy at 5 g/s are due to the flowmeter and are discussed in the text.

- 65 -
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Fig. 6F.2. Vertical vibration test of Ball-in-Race Flowmeter. The

actual flowrate is 10 g/s, and the flowrate ratio is averaged over

100 pulses from the Ball-in-Race Flowmeter. The sweep from 1 to

1000 Hz took 20 minutes.

- 66 -
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Fig. 6F.3. Ball- in-Race Flowmeter vibrated horizontally in direction

of inlet and outlet fuel lines. Other conditions are the same as in

Fig. 6F.2.

- 67 -
6G Ball and Spring Flowmeter

This flowmeter, described in Appendix G, leaked around the inlet fitting

when it was first installed. The leak was stopped with epoxy, but after

the flowmeter was used for a while, leaking again occurred around the

outlet and around the photodiode mounting. These leaks were stopped

with epoxy, and the flowmeter was tested.

A calibrator supplied with the flowmeter was used as shown in Fig. 6G.1

to verify that the flowmeter was properly adjusted. The adjustment was

checked before the steady flow tests started and again after the steady

flow tests were completed and found to meet the manufacturer's specification. Thus incorrect adjustment does not explain the day-to-day change

in the steady flow data reported in Table 6G.1 and Fig. 6G.2. The day-today change is not due to bubbles in the flow either. This follows from

the transfer standard flowmeter's total mass indication, which did not

change more than .3 percent from day to day, and that was only at the

lowest flowrate.

The effect of supply voltage on flowmeter indication is shown in Table

6G.2. The flowmeter is useful, however, as a real time indicator of the

fuel flowrate through the needle valve and into the float bowl as shown

in Fig. 6G.3. Although the flowmeter may not give a completely accurate

indication of the time dependence of the fuel flow, it does show that the

flow itself is quite erratic.

Table 6G.1

Ball and Spring Flowmeter

Steady Flow Test

Actual Flowmeter Indicator Meter

Flowrate Indication Fluctuation Factor*

(m£/s) (GPH)

rst

(GPH) (Ideally=l)

Fi Day

1.66 1.5 + 0.2 1.06

2.66 3 + 0.2 .84

4.77 6 + 0.2 .76

6.05 9 + 0.3 .64

7.81 12 + 0.3 .62

9.00 15 + 0.5 .57

Sec ond Day

3.18 1.5 + 0.4 2.01

4.73 3 + 0.1 1.50

7.19 6 + 0.4 1.14

9.51 9 + 0.5 1.00

11.8 12 + 0.5 .94

13.4 15 + 0.5 .85

Average Temperature = 23°C, Average Density = 0.7474 g/m£

^Conversion factor times the actual flowrate divided by indicated

flowrate.

- 68 -
Table 6G.2

Ball and Spring Flowmeter

Supply Voltage Test

Actual Flowrate =7.60 m£/s (7.23 GPH)

Supply Indicated

Voltage Flowrate

(Volts DC) (GPH)

9.3

10.0 1.7

10.5 3.1

10.95 4.6

11.45 6.6

11.9 8.6

12.5 9.2

12.9 9.5

13.5 10.0

14.0 10.3

14.6 10.5

15.0 11.5

Average Temperature = 22°C, Average Density = 0.7259 g/m£

- 69 -
CALIBRATOR

Efa=.

er insertion, the I

ibrator shoulder must I

firmly against this 111,

Aft

cali

be

surface

Fig. 6G.1. Ball and Spring Flowmeter calibrator.

- 70
I I I I I I I I I

2.0 V

> ONE STANDARD DEVIATION —

1.8

LU

1—<cc% 1.6 — —

_l

u_ i

LU£ 1.4 — —

o

Q

Z

m 1.2

i—< X QC§ o 3 1.0 2 —

u_

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Z3 o X

fe 0.8 —

< §

0.6 o o

o -

0.4 I I I I I I I I I 8 10 12

INDICATED FL0WRATE

14 16 18 GPH

Fig. 6G.2. Ball and Spring Flowmeter calibration curve. The flowrate

ratio should be equal to one. The circles are for data taken on the

first day of testing, and the x's the second day. The day-to-day

change is due to the flowmeter as discussed in the text.

- 71 -
<

o

Q

w. ;'iV/s,:i i m m A/m: m\i\ i i,i,ti< •iij.jj .jli'u k

;

, ;ijijj%,./hUhijj.jui iiujij

liiti

600 s

Fig. 6G.3. Ball and Spring Flowmeter indicated flowrate versus time.

This shows that the fuel flow through the needle valve into the float

bowl is erratic.

- 72 -
7 DISCUSSION AND CONCLUSION

In the present work, flowmeter environment in an automobile was

surveyed. In light of this information, a procedure was developed

to test flowmeter performance in a laboratory simulation of that

environment. Sources of error in the tests were examined and

eliminated as much as possible. Tests on six flowmeters were

performed illustrating the results of the evaluation procedure.

Time and staff limitations prevented complete testing of all available

automotive fuel flowmeters. Tasks left undone include the following:

- Defining more completely the conditions of some of the tests, e.g.

characterizing the vapor bubble content in the fuel at high

temperatures.

- Extending the tests, e.g., to lower flowrates at high temperatures,

or e.g., vibrating the float bowl independently.

- Completing all of the present tests not performed here, e.g., tilting

the Automatic Burrette Flowmeter.

- Determining the long term effect of wear on flowmeter performance,

e.g., for the Four Piston Flowmeter.

- Testing with fuel injection rather than with a float bowl.

- Carrying out all tests on other kinds of automotive fuel flowmeters,

e.g., an $8000 flowmeter, which was not obtained for the present

tests because of its cost.

- Testing more than one automotive fuel flowmeter of a given model to

determine how typical the flowmeter defects are.

- Determining the causes for automotive fuel flowmeter inaccuracy.

- Modifying or redesigning flowmeters to eliminate defects and testing

the new version.

Testing as extensive as this would best be approached by a screening

process in which further tests would be made on a flowmeter only if

it performed satisfactorily on all previous tests. The tests would

not be performed in a fixed order; tests which the flowmeter is

expected to fail most significantly would be performed first.

- 73 -
APPENDIX. FLOWMETERS

The environment of a flowmeter in an automobile is sufficiently hostile

that it is not likely to measure fuel accurately unless specially designed

for this purpose. So, only flowmeters that are advertised for automotive

use were considered.

The advertised prices of flowmeters range from about $50 to $4000 and

have a claimed accuracy as good as 0.25 percent. Not all of them cover

the necessary 50 to 1 flow range. Several of them are available as miles-per-gallon (MPG) meters as well as instantaneous gallons-per-hour

or total fuel used meters. Only the fuel consumption versions will be

discussed

.

A. Four Orifice Flowmeter

The flowmeter used for the transfer standard is the Four Orifice Flowmeter,

shown schematically in Fig. A. It uses four matched orifices in a Wheatstone bridge arrangement. An orifice is in each of the fuel lines

that form the sides of the square. An internal pump maintains a constant

volume flow Q of fuel in a line that goes diagonally from one corner of

the square to the opposite one. The fuel then flows back along the

perimeter of the square in equal amounts on both sides. The fuel to

be measured enters at another corner of the square with volume flowrate

q, and the same quantity of fuel leaves to the carburetor from the last corner. The pressure drop AP divided by the internal pump volume flowrate

Q is proportional to the mass flowrate G of the fuel to be measured.

This can be seen as follows. Since the orifices are made as nearly

identical as possible and then selected from a large batch to form a matched set of four, the flow divides reasonably accurately as shown

in Fig. A. The flowrate through the lower left orifice for example is

Q + q /P P

= C

where P^n is the flowmeter inlet pressure, P is the pump inlet pressure,

p is the fuel density, and C is a constant. The flowrate through the

lower right orifice is

Q - * / pout

= c

where Pout is the flowmeter outlet pressure, and the constant C is the same because the orifices are matched. The difference between the squares

of these equations yields the mass flowrate

G = pQ = C

2 AP/Q,

where AP = Pin

- Pout is the measured pressure difference.

74 -
Fig. A. Four Orifice Flowmeter. The pump in the center maintains

a constant volume flowrate Q. If the four orifices are identical,

the total mass flow rate is given by G = pq = constant x AP/Q, where

AP is the pressure drop across the meter.

- 75 -
This flowmeter is the only one that reads mass flow directly. All

others respond to volume flow. However, since the internal pump

rate must be held constant, a synchronous motor is used, which requires

115 V, 60 Hz A.C. This is easily supplied if the meter is used for

dynamometer testing. For mobile testing, a converter must be used,

which has a mass of 25 kg and draws about 50 A at 12 V.

B. Four Piston Flowmeter

The Four Piston Flowmeter has four pistons in a radial arrangement

as shown in Fig. B. The four pistons are connected to the same crank shaft. No valves are used; fuel flows through ports uncovered

by the pistons as they move. The ports are arranged so that the fuel

flow causes the crank to turn continuously. A vapor eliminator is

incorporated in the inlet. The magnitude and direction of rotation

of the crank shaft is determined by two light beams that each are interrupted ten times per revolution. The resulting pulses from two

light detectors are combined to determine direction of rotation and

counted by an up-down counter so that back flow is subtracted automatically. The readout displays total fuel used in milliliters with

1 ml increments and also displays fuel temperature and pressure.

C. Positive Displacement Pump Flowmeter

The Positive Displacement Pump Flowmeter uses a piston pump run by

a variable speed motor. The piston is rigidly attached to its connecting

rod, and the axis of the cylinder is at a slight angle to the shaft of

the motor. The connecting rod is coupled to the shaft by a pin travelling

in a wavy groove, and this causes the piston to move back and forth in

the cylinder as the shaft turns. Calibration can be adjusted by changing

the angle. The volume displaced per piston stroke times the number of

strokes gives the flow measurement. The speed of this calibrated pump

is automatically varied to maintain constant output pressure. A

schematic diagram is shown in Fig. C. Input pressure is boosted

and held constant by another pump. A vapor diverter purges bubbles

from the fuel before metering. An electromagnetic counter records total

fuel used in 0.001 gallon increments. The average current used at 12

volts is 3 to 6A depending on flowrate. However, peak current can be

as high as 20 A.

D. Turbine Flowmeter

The Turbine Flowmeter has a bypass line around it and a diaphragm

blocking the bypass line. Because of the diaphragm no fuel flows in

the bypass on the average. But the fuel does flow back and forth in

it pushing the diaphragm back and forth. Meantime fuel is flowing

through the turbine meter causing its rotor to rotate. The bypass

line is intended to smooth out the flow through the turbine meter. A

light beam is interrupted by the blades of the turbine rotor every

time one goes by. The resulting signals are counted and displayed

digitally with 0.01 gallon increments.

- 76 -
Piston

Connecting

Rod

Crankshaft

Fig. B. Four Piston Flowmeter. The crankshaft is caused to rotate

by the flowing fluid. The rotation is detected optically.

- 77 -
r

PRE-METER

PRESSURE

IN *

CHECK VALVE

30 PSI >

16

VAPOR

PURGE

ELECTRIC PUMP

(Etggurg Booster)

BY-PASS

] VALVE

FILTER/VAPOR

SCAVENGER

r-ElQW OUTPUT

H FREQUENCY

REMOTE

START/STOP

PUMP

rC

Q

PRESSURE TRANSDUCER

DIGITAL CONTROLLER

nffl«fb3T

POST METER

PRESSURE

»- OUT

COUNTER

1/1000 GAL

J"

D +12VDC

Fig. C. Positive Displacement Pump Flowmeter. When the pressure

transducer detects a decrease (increase) in the output pressure, the

digital controller causes the pump to increase (decrease) the flowrate. The pulses to the pump are divided by 12 and used to advance

the counter 1/1000 gallon.

- 78 -
E. Automatic Burrette Flowmeter

The Automatic Burrette Flowmeter has an automatically filled .01 gallon

container as shown in Figs. E.l and E.2. The contents of the container

are dumped on demand into a reserve tank that holds three times as much

as the container. A pump at the outlet of the reserve tank pumps the

fuel to the carburetor. When the fuel level in the reserve tank drops

far enough, a level sensor initiates the cycle. The container is then

filled by incoming fuel until a level sensor set for .01 gallon is

actuated. This stops the flow of the incoming fuel and causes the

container contents to be dumped into the reserve tank. The number of

times the container is filled is counted by an electromagnetic counter,

which records total fuel used in .01 gallon increments.

F. Ball-in-Race Flowmeter

The Ball-in-Race Flowmeter has an opaque ball that travels through a toroidal passage, i.e. a passage shaped like the dough of a donut. The

ball is pushed along by a jet of fuel every time it comes around the

toroid. The fuel travels three fourths of the way around the toroid

behind the ball and then exits while the ball coasts along to where it

gets pushed again. Each time the ball goes around the toroidal passage

it interrupts a light beam. This interruption is turned into an electric

pulse, which is counted. The readout gives a digital reading in .01

gallon increments of the total fuel used.

G. Ball and Spring Flowmeter

The Ball and Spring Flowmeter is a variable area flowmeter. A spring

pushes an opaque ball into a tapered translucent tube whose diameter

decreases with distance into the tube as shown in Fig. G. The farther

into the tube the ball goes, the tighter it fits. At the end of the

tube is an orifice, and the spring pushes the ball against it covering

it. The fuel flows out of the orifice pushing the ball away so it can flow through the annular area around the ball . This annular area increases continuously as the ball moves along the tube. The faster

the fuel flows, the more cross sectional area needed for the fuel, and

so the farther along the tube the ball gets pushed. As the ball moves

back it increasingly uncovers a beam of light so that more light shines

on a photodiode decreasing its electrical resistance. The resistance

is measured to give the flowrate. The light bulb is powered through a voltage regulator so that changes in the car battery voltage will not

affect the flow measurement. A red filter is used to prevent errors

due to gasoline color changes. The flowrate is displayed on an analog

readout with a readability of about 0.2 gallon/hour.

- 7<
ur

Fig. E.l. Automatic Burette Flowmeter, just before filling the measuring

chamber. In this illustration, the level sensor at (A) has activated the

magnetic coil at (B) and the balls at (C) and (D) are raised, opening the

port at (E) and closing the outlet at (F) . Fuel enters the measuring

chamber at (G) and the float (H) raises toward the level sensor (I).

- 80 -
ErA\yfega

Fig. E.2. Automatic Burette Flowmeter just after filling the measuring

chamber. In this illustration, the coil (B) has been discharged by the

action of the liquid level sensor at (I) , and the balls at (C) and (D)

have fallen back, closing the port at (E) and opening outlet at (F)

.

Fuel in the measuring chamber (G) will now flow into the reservoir (J)

.

The counter at (L) records the addition of this increment as it passes

into the reservoir.

81
STAINLESS

STEEL SPRING

TO /L. NGINE NTTRANSPARENT

FLOWTUBE

— GROUND RED RED

(

|C A L I B R A T I N G^* i *^

I POTENTIOMETER

,1, (1000 Ohms) M/W " BLAC

FLOWTRANSDUCER

^

INDICATING GAUGE

GROUND

Fig. G. Ball and Spring Flowmeter. The flowing fluid pushes the ball

against the spring. The farther back the ball is pushed, the more light

from the lamp strikes the photodiode, the lower its resistance, the more

current flows in the circuit, and the greater the indicated flowrate on

the gauge.

- 82 -
APPENDIX H. THERMISTOR CALIBRATION

The thermistor probes used for each test are as follows:

Meter

- Four Orifice Flowmeter

- Four Piston Flowmeter

- Positive Displacement Pump Flowmeter

- Turbine

- Automatic Burrette Flowmeter

- Ball and Race Flowmeter

- Ball and Spring Flowmeter

Probe Numbers

1 & A

1 & 4

1 & 4

1 (#2 during heated test)

1 & 2

1

1

The Reports of Test for these probes follow .

- 83 -
FORM NBS-259

(3-68)

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

WASHINGTON. D.C. 20234

REPORT OF TEST

Thermistor Probes #1 and #5

Digital Display Unit S/N 559

Submitted by

National Bureau of Standards

Division 213, Section 06

The thermistor probes were calibrated by intercomparison with a standard

platinum resistance thermometer in stirred liquid baths at 13 temperatures.

An ice point was taken by immersing the probes in an ice bath. The probes were immersed to a depth of 4 1/2 inches and the zero was checked before

each reading. For temperatures below °C the readings were taken on the

-30 °C to +50 °C range, and for temperatures at °C through 100 °C the

readings were taken on the 0-100 °C range. The results obtained are given

in tabular form below.

Temperature

°C Probe No. Correction (IPT-S-68)

1 5

-30.00

-20.00

-10.00

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

-0.20 + .14

- .07

- .26 + .20 + .03 - .14

- .11 + .06 + .18 + .13

- .02

- .10 + .22

-0 .28 + .07 - .11 - .30 + .15

.00

- .17

- .14 + .04 + .16 + .11 - .05 - .13 + .19

All temperatures in this report are based on the International Practical

Temperature Scale of 1968, IPTS-68. This temperature scale was adopted by

the International Committee of Weights and Measures at its meeting in

October, 1968, and is described in "The International Practical Temperature

Scale of 1968," Metrologia, Vol. 5, No. 2, 35 (April, 1969).

For the Director

Institute for Basic Standards

Test No. 311-9-75

Completed: October 28, 1975

JAW:NMcB

James F. Schooley

Chief, Temperature Section

Heat Division

- 84 -
FORM NBS-2S9

(3-ee)

U.S. Department of Commerce

NATIONAL BUREAU OF STANDARDS

WASHINGTON. D.C. 20234

REPORT OF TEST

Thermistor Probes #2 and #6

Digital Display Unit S/N 705

Submitted by

National Bureau of Standards

Division 213, Section 06

The thermistor probes were calibrated by intercomparison with a standard

platinum resistance thermometer in stirred liquid baths at 13 temperatures.

An ice point was taken by immersing the probes in an ice bath. The probes were immersed to a depth of 4 1/2 inches and the zero was checked before

each reading. For temperatures below °C the readings were taken on the

-30 °C to +50 °C range, and for temperatures at °C through 100 °C the

readings were taken on the 0-100 °C range. The results obtained are given

in tabular form below.

Temperature Correction (IPTS-68)

°C Probe No. 2 6

-30.00 -0.19

-20.00 + .18

-10.00 - .03

0.00 - .14 -.18

10.00 + .28 +.25

20.00 + .10 +.07

30.00 - .08 -.12

40.00 - .07 -.11

50.00 + .09 +.04

60.00 + .20 +.14

70.00 + .14 +.07

80.00 - .03 -.11

90.00 - .12 -.22

100.00 + .19 +.13

All temperatures in this report are based on the International Practical

Temperature Scale of 1968, IPTS-68. This temperature scale was adopted by

the International Committee of Weights and Measures at its meeting in

October, 1968, and is described in "The International Practical Temperature

Scale of 1968," Metrologia, Vol. 5, No. 2, 35 (April, 1969).

For the Director

Institute for Basic Standards

James F. Schooley

Test No. 311-9-75 Chief, Temperature Section

Completed: October 28, 1975 Heat Division

JAW:NMcB

- 85 -
FORM NBS-2S9

(3-«6)

U.S. Department of Commerce

NATIONAL BUREAU OF STANDARDS

WASHINGTON. D.C. 20234

REPORT OF TEST

Thermistor Probes #3 and #7

Digital Display Unit S/N 706

Submitted by

National Bureau of Standards

Division 213, Section 06

The thermistor probes were calibrated by intercomparison with a standard

platinum resistance thermometer in stirred liquid baths at 13 temperatures,

An ice point was taken by immersing the probes in an ice bath. The probes were immersed to a depth of 4 1/2 inches and the zero was checked before

each reading. For temperatures below °C the readings were taken on the

-30 °C to +50 °C range, and for temperatures at °C through 100 °C the

readings were taken on the 0-100 °C range. The results obtained are given

in tabular form below.

Temperature Correction (IPTS-68)

°C Probe No. 3 7

-30.00 -0.24 -0.30

-20.00 + .14 + .10

-10.00 - .05 - .08

0.00 - .22 - .20

10.00 + .24 + .26

20.00 + .08 + .11

30.00 - .09 - .07

40.00 - .06 - .03

50.00 + .13 + .14

60.00 + .25 + .26

70.00 + .20 + .22

80.00 + .03 + .06

90.00 - .06 - .02

100.00 + .26 + .33

All temperatures in this report are based on the International Practical

Temperature Scale of 1968, IPTS-68. This temperature scale was adopted by

the International Committee of Weights and Measures at its meeting in

October, 1968, and is described in "The International Practical Temperature

Scale of 1968," Metrologia, Vol. 5, No. 2, 35 (April, 1969).

For the Director

Institute for Basic Standards

James F. Schooley

Test No. 311-9-75 Chief, Temperature Section

Completed: October 28, 1975 Heat Division

- 86 -
FORM NBS-259

(3-«6>

U.S. Department of Commerce

NATIONAL BUREAU OF STANDARDS

WASHINGTON, D.C. 20234

REPORT OF TEST

Thermistor Probe #4

Digital Display Unit S/N 634

Submitted by

National Bureau of Standards

Division 213, Section 06

The thermistor probe was calibrated by intercomparison with a standard

platinum resistance thermometer in stirred liquid baths at 13 temperatures.

An ice point was taken by immersing the probe in an ice bath. The probe was immersed to a depth of 4 1/2 inches and the zero was checked before

each reading. For temperatures below °C the readings were taken on the

-30 °C to +50 °C range, and for temperatures at °C through 100 °C the

readings were taken on the 0-100 °C range. The results obtained are given

in tabular form below.

Temperature

°C

-30.00

-20.00

-10.00

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

All temperatures in this report are based on the International Practical

Temperature Scale of 1968, IPTS-68. This temperature scale was adopted by

the International Committee of Weights and Measures at its meeting in

October, 1968, and is described in "The International Practical Temperature

Scale of 1968," Metrologia, Vol. 5, No. 2, 35 (April, 1969).

For the Director

Institute for Basic Standards

(/

James F. Schooley

Test No. 311-9-75 Chief, Temperature Section

Completed: October 28, 1975 Heat Division

JAWrNMcB - 87 -

Correction (IPTS-68)

Probe No. 4

-C .19 + .18

.00

- .11 + .35 + .18

.00

.00 + .15 + .25 + .19 + .01

- .08 + .23
REFERENCES

1. "Preliminary Recommended Environmental Practices for Electronic

Equipment Design" proposed by the Environmental Standards & Test

Methods Subcommittee of the Electronic Systems Committee, Society

of Automotive Engineers and presented at the International

Colloquium on Automotive Electronic Technology, October, 1974,

(SAE, 1974).

2. H. I. Wilson, "Fuel System Time-Temperature Histories During

Specified Car Use Patterns." Paper No. 720080, Trans. SAE (1974).

3. Milton Baker, James Callison, (private communication).

4. American Association of State Highway and Transportation Officials.

5. Ernest Johnson (private communication).

6. ASTM Specification E100-72 (American Society of Testing Materials,

Philadelphia, Pa., 1972).

7. ASTM Method D323-72 (American Society of Testing Materials,

Philadelphia, Pa., 1972).

8. ASTM Method D287-67 (American Society of Testing Materials,

Philadelphia, Pa., 1972).

9. ASTM-IP Petroleum Measurement Tables. (American Society of

Testing Materials, Philadelphia, Pa., 1952).

* U. S. GOVERNMENT PRINTING OFFICE :1977--240-848/215

88
-HBS--M4A (R ev. t-t o)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS TN 943

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

Evaluation of Automotive Fuel Flowmeters

5. Publication Date June 1977

6. Performing Organization Code

7. AUTHOR(S)

Baldwin Robertson and G. Paul Baumgarten

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON. D.C. 20234

10. Proiect/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

U.S. Department of Transportation

Office of the Secretary

Office of the Assist. Sec. for Systems Development and Tech.

Washington, D.C. 20590

13. Type of Report & Period Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Fuel economy measurement procedures being developed by the Transportation Systems

Center of the Department of Transportation require flowmeters to measure the gasoline

consumed by the engine of an automobile either on the road or on a dynamometer. The

contribution of the National Bureau of Standards to this work was to ascertain the

environment in which the flowmeters will probably be used, to develop procedures for

measuring their performance in a laboratory simulation of that environment, and to

carry out illustrative measurements on a number of flowmeters.

This report discusses: (1) the environment of the flowmeter in an automobile, i.e.,

flowmeter temperature; fuel temperature, pressure, density, viscosity, color, opacity,

flow pulsations, back flow, and swirl due to elbows; line voltage fluctuations;

electromagnetic radiation from ignition; vehicle attitude with respect to the vertical;

and vibration, (2) the test set-up and procedure used for evaluating and calibrating

these meters in the laboratory under conditions simulating the automotive environment,

(3) a discussion of possible sources and magnitudes of errors in the calibration, and

(4) results of illustrative tests on seven flowmeters.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Automotive environment; Automotive fuel flowmeters; Effect of environment on flowmeter

performance; Flowmeter calibration; Flowmeter evaluation; Procedure for testing

flowmeters

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