ASTM D1070-85(1998)
(Test Method)Standard Test Methods for Relative Density of Gaseous Fuels
Standard Test Methods for Relative Density of Gaseous Fuels
SCOPE
1.1 These test methods cover the determination of relative density (specific gravity) of gaseous fuels, including liquefied petroleum gases, in the gaseous state at normal temperatures and pressures. The test methods specified are sufficiently varied in nature so that one or more may be employed for laboratory, control, reference, gas measurement, or in fact for any purpose where it is desired to know the relative density of gas or gases as compared to the density of dry air at the same temperature and pressure.
1.2 The procedures appear in the following sections: Section Method A, Ac-Me Gravity Balance 7 to 9 Method B, Ac-Me Recording Gravitometer 10 to 12 Method C, Arcco-Anubis Recording Gas Gravitometer 13 to 15 Method D, Arcco-Anubis Portable Gas Balance 16 to 18 Method E, Kimray Gravitometer 19 to 21 Method F, Ranarex Recording and Indicating Gravitometer 22 to 23 Method G, UGC Gravitometer 24 to 26
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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Designation: D 1070 – 85 (Reapproved 1998)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Methods for
Relative Density of Gaseous Fuels
This standard is issued under the fixed designation D 1070; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 density—mass per unit of volume of the fuel gas or air
being considered.
1.1 These test methods cover the determination of relative
3.1.2 gaseous fuel—material to be tested, as sampled, with-
density (specific gravity) of gaseous fuels, including liquefied
out change of composition by drying or otherwise.
petroleum gases, in the gaseous state at normal temperatures
3.1.3 relative humidity—ratio of actual pressure of existing
and pressures. The test methods specified are sufficiently varied
water vapor to maximum possible pressure of water vapor in
in nature so that one or more may be used for laboratory,
the atmosphere at the same temperature, expressed as a
control, reference, gas measurement, or in fact, for any purpose
percentage.
in which it is desired to know the relative density of gas or
3.1.4 relative density—ratio of the density of the gaseous
gases as compared to the density of dry air at the same
fuel, under the observed conditions of temperature and pres-
temperature and pressure.
sure, to the density of dried air, of normal carbon dioxide
1.2 The procedures appear in the following sections:
content, at the same temperature and pressure.
Section
Method A, Ac-Me Gravity Balance 7-9
NOTE 2—In these test methods the term “relative density” has replaced
Method B, Ac-Me Recording Gravitometer 10-12
the term “specific gravity.” The term, specific gravity, as used in the
Method C, Arcco-Anubis Recording Gas Gravitometer 13-15
previous edition of these test methods, was not technically correct usage.
Method D, Arcco-Anubis Portable Gas Balance 16-18
Method E, Kimray Gravitometer 19-21
Method F, Ranarex Recording and Indicating Gravitomete 22 and 4. Summary of Test Methods
4.1 Method Using Pressure Balances—In this test method,
Method G, UGC Gravitometer 24-26
a beam carrying a bulb and counterweight is brought to
NOTE 1—The test methods and apparatus described herein are repre-
balance, successively in air and in gas, by adjusting the
sentative of methods and apparatus used broadly in industry. Manufactur-
pressure within the balance case. The absolute pressures are
er’s instructions for specific models should be consulted for further details
determined by means of a barometer and a mercury-filled
as supplements to the information practical to cover here. It is not intended
to imply that there are not other equally accurate and satisfactory
manometer, and the relative density is computed from the ratio
instruments commercially available or that others will not be developed in
of absolute pressures. Pressure balance instruments vary in
the future.
size, method of supporting the balance beam, sealing the
1.3 This standard does not purport to address all of the balance case, and other minor details of construction. However,
safety concerns, if any, associated with its use. It is the they are all subject to corrections and errors of the same kind,
responsibility of the user of this standard to establish appro- although not necessarily of the same magnitude.
4.2 Method Using Displacement Balances—This test
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. method uses instruments that depend on the principle of
balancing the weight of a given volume of gas at atmospheric
2. Referenced Documents
pressure by displacement of the center of gravity of a balance
2.1 ASTM Standards: beam. The amount of this“ deflection,” subject to correction,
D 1145 Test Method of Sampling Natural Gas measures the relative density. Instruments of this class may be
D 1247 Method of Sampling Manufactured Gas either of the indicating or recording type. Apparatus of this
general classification varies even more widely in construction
3. Terminology
than the pressure balance covered in 4.1.
3.1 Definitions:
4.3 Centrifugal Force Methods—This test method measures
the difference in centrifugal force between the gaseous fuel
being tested and a reference gas (air), as both are accelerated
These test methods are under the jurisdiction of ASTM Committee D-3 on
by a specially designed wheel.
Gaseous Fuels and is the direct responsibility of Subcommittee D 03.03 on
Determination of Heating Value and Relative Density of Gaseous Fuels.
4.4 Kinetic Energy—This test method measures the ratio of
Current edition approved March 29, 1985. Published June 1985. Originally
the change in kinetic energy between an impeller and an
published as D 1070 – 52. Last previous edition D 1070 – 73 (1979).
2 impulse wheel operating in gas and another impeller and
Discontinued—See 1986 Annual Book of ASTM Standards, Vol 05.05.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1070
impulse wheel operating in a reference gas (air). These balance. Close first valve.
measurements are in terms of the torques of the impulse wheels
8.1.2.2 Open second valve and pull a vacuum of about 650
that are proportional, respectively, to the gas and air densities.
mm, then close second valve. Unlock the balance beam by
turning locking level counterclockwise. The beam will then be
5. Significance and Use
in an unbalanced position with the zero above the hairline
5.1 These test methods provide accurate and reliable meth-
indicator.
ods to measure the relative density of gaseous fuels on an
8.1.2.3 Observe the scale from such a position that the
intermittent or continuous basis, which may be used for
reflection of your eye in the look glass is centered on the
regulatory or contract compliance custody transfer and process
hairline. Admit air through first valve and air dryer until the
control.
beam begins to fall. Then pinch down the flow of air through
first valve so that the air can be cut off at exactly the right
6. Sampling
instant to keep the beam in the balanced position. Observe the
6.1 The sample shall represent the gas being sampled and
scale noting how far the zero swings above and below the
shall be taken from its source without change of form or
hairline. The beam is balanced when the zero of the scale is
composition. Sample natural gases in accordance with Test
swinging an equal amount above and below the hairline.
Method D 1145. Sample manufactured gases in accordance
8.1.2.4 When balance is obtained, lock instrument and read
with Method D 1247.
and record the air vacuum shown on the manometer. Record
METHOD A—Ac–Me GRAVITY BALANCE
the temperature within the balance.
(Four-Spring Type)
8.1.3 Gas Reading:
8.1.3.1 Close the valve on the air dryer and close Valve 1.
7. Apparatus
Then open Valve 2 and pull a vacuum of about 650 mm on the
7.1 Ac–Me Gravity Balance (Four-Spring Type), pressure-
balance.
tight cylindrical container mounted on a base board. Inside the
8.1.3.2 Open gas supply valve and admit gas to the balance
container is a balance beam with a sealed float at the back and
until the pressure reads about 650 mm. (Do not exceed
graduated scale at the front. The beam is suspended at the
manometer maximum reading or the balance may be dam-
center by thin flat springs. A window for viewing the scale is
aged.)
provided at the front of the container. The balance beam may
8.1.3.3 Repeat 8.1.3.1 and 8.1.3.2 three times. The third
be locked by a cam mechanism when the instrument is not in
time will leave only about 0.05 % air in the balance. If the
use. Valves for introducing gas and air samples are provided.
balance is purged by flowing gas through it, the purging should
7.2 Carrying Case, for transportation or storage.
be continued until two successive readings (8.1.3.4) check.
7.3 Air Dryer, to dehydrate air samples (silica gel).
8.1.3.4 Unlock the instrument and release gas pressure
7.4 Tripod, to support the balance firmly.
through Valve 2 until balanced position of beam is reached.
7.5 Pressure-Vacuum Pump, to transfer samples and adjust
Follow the same method as described for the air reading in
pressure in the balance.
8.1.2.4. When balance is obtained, lock the instrument and
7.6 Mercury Manometer, 760 mm, to measure pressure in
record the gas pressure shown on the manometer. Record the
the balance.
temperature in the balance.
7.7 Aneroid Barometer, temperature compensated to con-
vert balance pressure readings to absolute pressures. (Absolute
NOTE 3—When the gas supply is under a vacuum or has a high content
pressure not corrected to sea level.)
of hydrocarbons heavier than ethane, keep the gas pressure within the
7.8 Rubber Hose, 6.35 mm ( ⁄4-in.) inside diameter, four
balance below that in the source line or container to avoid condensation in
the balance. If necessary, readjust instrument to balance on gas at a
lengths with brass swivel connections to join the balance to its
vacuum about 20 mm higher than that in the sampling source.
operating accessories.
7.9 Sampling Hose, 6.35 mm ( ⁄4 in.) with swivel connec-
8.1.4 Air Check Reading:
tions and two male 6.35-mm ( ⁄4-in.) pipe adapters.
8.1.4.1 Close gas supply valves. Open second valve and pull
7.10 Additional Apparatus—Refer to the manufacturer’s
a vacuum of about 650 mm.
literature for further information on sizes, assembly, and other
8.1.4.2 Admit air through the air dryer to the balance until
details applicable to specific models.
atmospheric pressure is reached. Close first valve.
8. Procedure 8.1.4.3 Repeat 8.1.4.1 and 8.1.4.2 at least three times or
until two successive readings (8.1.4.4) will check.
8.1 Assemble and set up the balance in accordance with the
8.1.4.4 Open second valve and pull a vacuum of about 650
manufacturer’s instructions, making certain that it is firmly
nm, then close second valve. Unlock instrument; admit air
supported, level, and is not disturbed during the entire test.
through first valve to bring the beam to the balanced position
Take and record the following four readings:
as when taking the first air reading.
8.1.1 Average Barometric Reading—Read the aneroid ba-
rometer at the beginning and end of each test, and record the 8.1.4.5 When balance is obtained, lock instrument; read and
average of these two readings. record the air vacuum shown on the manometer. Record the
8.1.2 Air Reading: temperature in the balance. This reading must check with the
8.1.2.1 Admit air through first valve and air dryer until first air reading if the two temperatures in the balance are the
atmospheric pressure is reached. Record temperature in the same. When test is complete close all valves on the balance.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 1070
Close the cock on the air dryer to prevent moistening of silica pressure. In this way, a continuous sample and relative density
gel. record is obtained.
10.2 Since the weight of the gas sample in the float is
9. Calculation
compared to ambient air, it is necessary to compensate for
barometer and temperature changes to obtain relative density at
9.1 When an aneroid barometer is used in the field, it should
standard conditions. The automatic compensator consists of a
be checked periodically with a mercury barometer. The barom-
mercury container positioned vertically above the balance
eter should be handled very carefully and be well packed for
point of the balance beam, a mercury gage, and a dry air-filled
transportation. If barometer reading is in inches and fractions,
tube for sensing temperature changes. As variations in atmo-
multiply reading by 25.4 to convert to millimetres. To convert
spheric temperature take place, the pressure in the closed tube
to absolute pressure, add barometric pressure in millimetres to
will vary accordingly; for instance, an increase in pressure is
both air and gas pressure readings. (If air or gas reading is on
indicated by a plus reading on the mercury gage scale. The
vacuum, subtract it from barometric pressure.) Divide the
mercury displaced out of the gage by the increase in pressure
absolute pressure for air by the absolute pressure for gas to
is moved into the mercury container. This adds weight above
obtain the relative density of the gases shown in the following
the balance point and changes the center of gravity of the
example:
balanced system the proper amount to correct the relative
Manometer Barometer Absolute
Reading Reading Pressure
density record for the temperature rise which took place.
Variations in barometric pressure are compensated in a similar
Barometer reading:
manner since the mercury container is open to the atmosphere
753 mm
Air reading −127 + 753 5 626
and changes in barometric pressure will also force mercury in
Gas reading 204 + 753 5 957
or out of the container.
Air check reading −127
10.2.1 The Ac–Me gravitometer is housed in a heavy sheet
absolute air pressure
Relative density 5 (1)
metal case which protects the working parts. The case has
absolute gas pressure 5 626/957 5 0.654
access doors at the top and side for use when adjustment or
9.2 When there is a difference between the temperature for
cleaning is required. The gas sample enters the instrument and
the air reading and the temperature for the gas reading, these
is immediately reduced in pressure by an internal regulator,
temperature readings should be converted to absolute tempera-
then passes to a small flowmeter which indicates approximate
ture, by adding 460, and used in calculations as shown by the
sample rate. An inlet valve is incorporated in the flowmeter for
following example:
adjustment of the sample rate. The gas then flows through the
Absolute Absolute
inlet tubing to the bottom of the instrument and up through the
Manometer Pressure, Temperature Temperature,
float. It is discharged at the bottom past a seal of mineral oil
Reading P °F T
and exhausts through a large diameter pipe to the outlet.
Barometer reading:
10.2.2 The balance beam is near the center, mounted on
745 mm
knife edges and bearings. It supports the float at one end and
Air reading −95 650 66 526
Gas reading 197 942 68 528
the balance weight with microweights at the other
...
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