ASTM D1826-94(1998)
(Test Method)Standard Test Method for Calorific (Heating) Value of Gases in Natural Gas Range by Continuous Recording Calorimeter
Standard Test Method for Calorific (Heating) Value of Gases in Natural Gas Range by Continuous Recording Calorimeter
SCOPE
1.1 This test method covers the determination with the continuous recording calorimeter (Note 1) of the total calorific (heating) value of fuel gas produced or sold in the natural gas range from 900 to 1200 Btu/standard ft . Note 1-An extensive investigation of the accuracy of the Cutler-Hammer recording gas calorimeter, when used with gases of high heating value, was made by the National Bureau of Standards in 1957 under a research project sponsored by the American Gas Association.
1.2 The subjects covered in this test method appear in the following sections: Sections Air-Gas Ratio Test 11 Apparatus 5 Basis of Measurement 14 Cold Balance Test 10 Compensation of Complicating Factors 13 Condition of Gas Sample 7 Definitions 2 Installation of Apparatus 6 Maintenance, Appendix I X1 Operating Precautions, Appendix II X2 Operation and Checking of Apparatus 9 Precision 15 Scope 1 Significance and Use 4 Standardization of Calorimeter 12 Standardization, Preliminary, of Calorimeter by Hydrogen 8 Summary of Test Method 3
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D1826–94 (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 Method for
Calorific (Heating) Value of Gases in Natural Gas Range by
Continuous Recording Calorimeter
This standard is issued under the fixed designation D1826; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
NOTE 2—The defining relationships are:
1. Scope
−1 −1
(a) 1 Btu·lb 52.326 J·g (exact)
1.1 This test method covers the determination with the
(b) 1 lb5453.59237 g (exact).
continuous recording calorimeter (Note 1) of the total calorific
By these relationships, 1 Btu 5 1 055.05585262 J (exact). For most
(heating) value of fuel gas produced or sold in the natural gas
purposes, the value rounded to 1 Btu 5 1 055.056 J is adequate.
range from 900 to 1200 Btu/standard ft .
2.1.3 combustion air—air used for combustion, a total of
NOTE 1—An extensive investigation of the accuracy of the Cutler- the portion mixed with the gas as primary air and the air
Hammer recording gas calorimeter, when used with gases of high heating
supplied around the burner tube as secondary air (theoretical
value, was made by the National Bureau of Standards in 1957 under a
air plus excess air).
research project sponsored by the American Gas Association.
2.1.4 flue gases—the products, of combustion remaining in
1.2 The subjects covered in this test method appear in the
the gaseous state, together with any excess air.
following sections:
2.1.5 heat-absorbing air—the heat exchange medium used
Sections to absorb the heat of combustion derived from the burning of
Air-Gas Ratio Test 11
gaseous fuel.
Apparatus 5
2.1.6 saturated basis—the expressed total calorific value of
Basis of Measurement 14
Cold Balance Test 10
a gas when it is saturated with water vapor at standard
Compensation of Complicating Factors 13
temperature and pressure; 1 ft of this gas is equivalent in dry
Condition of Gas Sample 7
gascontentto0.9826ft ofdrygasatthestandardtemperature
Definitions 2
Installation of Apparatus 6 of 60°F and standard pressure of 14.73 psia.
Maintenance Appendix X1
NOTE 3—Thedefinitionsgivenin2.1.6and2.1.10arefortotalcalorific
Operating Precautions Appendix X2
Operation and Checking of Apparatus 9
(heating) values per standard cubic foot of gas. The definitions corre-
Precision 15
sponding to any other unit quantity of gas are obtained by substituting the
Scope 1
name of the desired unit in place of the term “standard cubic foot” in the
Significance and Use 4
definitions. Methods of calculating calorific (heating) values per cubic
Standardization of Calorimeter 12
foot of gas under any desired conditions of pressure, temperature, and
Standardization, Preliminary, of Calorimeter by Hydrogen 8
water vapor content are specified in Section 14.
Summary of Test Method 3
2.1.7 standard cubic foot of gas—the quantity of any gas
1.3 This standard does not purport to address all of the
that at standard temperature and under standard pressure will
safety concerns, if any, associated with its use. It is the
fill a space of 1 ft when in equilibrium with liquid water.
responsibility of the user of this standard to establish appro-
2.1.8 standard pressure—is 14.73 psia.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
NOTE 4—This is the pressure base adopted by the American National
Standards Institute in 1969 (Z132.1). According to Dalton’s law, this is
2. Terminology
equivalent to stating that the partial pressure of the gas is:
2.1 Definitions of Terms Specific to This Standard: 14.73−0.25636514.47364 psia
where 0.25636 is the vapor pressure of water in psia at 60°F.
2.1.1 The most important terms used in connection with the
determination of the calorific value of gaseous fuels in record-
2.1.9 standard temperature—60°F, based on the interna-
ing calorimetry are as follows:
tional practical temperature scale of 1968.
2.1.2 British Thermal Unit, or Btu—is the defined Interna-
2.1.10 total calorific value (gross heating value, higher
tional Tables British thermal unit (symbol Btu).
heating value)—of a gas is the number of British thermal units
evolved by the complete combustion at constant pressure of
one standard cubic foot of gas with air, the temperature of the
ThistestmethodisunderthejurisdictionofASTMCommitteeD-3onGaseous
gas, air, and products of combustion being 60°F, and all the
Fuels and is the direct responsibility of Subcommittee D03.03 on Determination of
Heating Value and Relative Density of Gaseous Fuels. water formed by the combustion reaction being condensed to
Current edition approved Feb. 15, 1994. Published April 1994. Originally
the liquid state.
e1
published as D1826–61T. Last previous edition D1826–88(1993) .
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D1826
NOTE 6—Refer to specific manufacturer’s manual for pictures of the
3. Summary of Test Method
recorder or the SMART-CAL, a digital indicating or printing device,
3.1 The heating value is determined by imparting all of the
currently used on new or retrofitted calorimeters.
heat obtained from the combustion of the test gas to a stream
6. Installation of Apparatus
of air and measuring the rise in temperature of the air. The
streams of test gas and heat absorbing air are maintained in 6.1 To secure the precise results that are possible with the
fixed volumetric proportion to each other by metering devices recording calorimeter, it is important that the instrument be
similar to the ordinary wet test meters geared together and installed so that the surrounding conditions will not introduce
drivenfromacommonelectricmotor.Themetersaremounted errors. In general, more precise results will be secured when a
in a tank of water, the level of which is maintained and the narrow range is maintained on the various conditions of the
calorimeter environment.
temperature of which determines the temperature of the enter-
ing gas and air. 6.2 Calorimeter Room—A typical installation of a single
recording calorimeter is shown in Fig. 4. The detailed require-
3.2 The flue gas resulting from combustion of the gas
(combustion products plus excess combustion air) is kept ments for the calorimeter room are given in Table 1.
separate from the heat-absorbing air and is cooled to a few
NOTE 7—Adetailed discussion of these requirements is included in the
degrees above the initial temperature of gas and air. The water
latest edition of the manufacturer’s instruction book covering the record-
formed in the combustion is practically all condensed to the
ing calorimeter. The information can be applied to all models of the
liquidstate.Consequently,thetemperatureriseproducedinthe instrument.
NOTE 8—The dimensions shown in Fig. 4 are for the latest model
heat-absorbing air is directly proportional to the heating value
calorimeter.
of the gas. Since all the heat from the combustion of the test
6.3 Gas Connection—Locatethesamplelinethatbringsthe
gas sample, including the latent heat of vaporization of the
gas to be tested to the calorimeter tank unit so that the heating
water vapor formed in the combustion, is imparted to the
valueisactuallyrepresentativeoftheconditionsexistinginthe
heat-absorbing air, the calorimeter makes a direct determina-
main gas line. Keep the sample line time lag as small as
tionoftotalheatingvalue.Thetemperatureriseismeasuredby
possible by (1) locating the calorimeter tank unit close to the
nickel resistance thermometers and is translated into Btu per
sample point, (2) running the sample line of small size pipe
standard cubic foot.
(Note 9), and (3) operating the sample line at low pressure.
4. Significance and Use
Provideanadditionalpurgeburnerorableedtoalowpressure
4.1 This test method provides an accurate and reliable
point.
method to measure the total calorific value of a fuel gas, on a
NOTE 9—Time lag may be calculated on the basis that the calorimeter
continuous basis, which is used for regulatory compliance,
uses about 1.2 ft /h.
custody transfer, and process control.
6.4 Electrical Wiring—The four leads for the resistance
5. Apparatus thermometers between either the recorder or the Smart-Cal
junction box and the tank unit shall be of No. 12 gage,
5.1 The recording calorimeter (Note 5) consists of two
insulated, solid copper wire without joints. Run in a separate
major units; the tank unit or calorimeter proper, Fig. 1, Fig. 2,
rigid metal conduit which is grounded and contains no other
and Fig. 3, in which the heating value of the test gas sample is
leads (Note 10). Power circuit wiring should be No. 14 gage,
measured; and the recording unit which translates the heat
insulated, solid or stranded, copper wire. Provide the supply
measurements into an indication of calorific (heating) value
line with a suitably fused disconnect switch. For the model
and records it graphically on a strip chart recorder or digitally
using an electronic recorder, it is essential that a suitable
if the new SMART-CAL is used (Note 6).
ground connection be made at both the recorder and the tank
NOTE 5—The previous specified pressure base was the absolute pres-
unit. Details are given in the manufacturer’s instructions.
sure of a column of pure mercury 30 in. in height at 32°F and under
standard gravity (32.174 ft/s ). This is equivalent to 14.7346 psia. NOTE 10—Where outdoor or underground wiring must be used, special
FIG. 1 Calorimeter—Schematic Flow Diagram
D1826
FIG. 2 Calorimeter—Layout Diagram
care should be exercised to protect the terminals of the cables from
the line from water accumulation, pitch the line to a low point
moisture to prevent grounds in the measuring circuit.
and provide a drip leg.
7.2 Chemical Contamination—The sample line should be
6.5 Initial Installation—When the calorimeter is first in-
practically free from hydrogen sulfide. A small, low-capacity
stalled, fill the tank unit with water (Note 11) and adjust it to
purifier can be constructed using iron oxide on wood shavings
a temperature that is 2 to 5°F below the normal room
as the purifying material. The time lag in the purifier adds to
temperature. Allow the unit to operate at least 24 h before
the sample line time lag so that the purifier should be of small
performing the detailed calibration tests.
capacity. A design that will purify about 3 ft of gas/h will be
NOTE 11—The water may be ordinary tap water supplied by most
satisfactory.
municipalities.If,however,itisfoundthatexcessivequantitiesofdeposits
and sludge are formed in short duration which interfere with satisfactory
8. Preliminary Standardization of Calorimeter by
performance, it will be necessary to use distilled or demineralized water
Hydrogen
with a pH of 7.
NOTE 12—For actual test instructions and other information, see the
8.1 The use of preliminary standardization by hydrogen test
appropriate instruction book provided by the manufacturer.
gasbeforetheuseofstandardmethaneatthetimeoftheinitial
6.6 Recorder Installation—Install the recorder so that the
installation or after any complete major overhaul of the tank
instrument is reasonably free from mechanical vibration. This
unit and recorder is required, because of the following factors:
is particularly important for those models in which a
8.1.1 Because of the low density of hydrogen, the presence
suspension-type galvanometer is used.
ofanyleaksinthesystemfromthegasmetertotheburnerwill
result in a definite low reading. This situation should certainly
7. Condition of Gas Sample
be considered on the initial installation and whenever the gas
7.1 Physical Contamination—The gas sample should be meterassemblyhasbeendismantledforinspectionorcleaning.
free of dust, water, and other entrained solids. If experience 8.1.2 The hydrogen test gives another cross-check of the
indicates that the foreign materials can enter the sample line, slide wire and thermometer calibration at a different point on
install a suitable sample line filter. To avoid any problems in the scale of the instrument. A satisfactory hydrogen test gives
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D1826
FIG. 3 Calorimeter Combustion Chamber
additional assurance that no error exists in this part of the following points should be checked periodically:
instrument. 9.1.1 Recorder—Check the operation of the recorder at
8.1.3 There is practically no possibility of incomplete com-
regular intervals to be sure that the chart is set at the proper
bustion on the hydrogen test. Therefore, a satisfactory hydro- time and that the pen is making a satisfactory line. Examina-
gen result gives assurance that, with the proper heat input, the
tions of the chart record will aid in avoiding certain operating
correct calorific value reading will be secured. If a satisfactory problems since the record will show if undesirable conditions
hydrogen test has been secured and a low reading has been develop. For example, an irregular chart may be the result of
obtained on the standard gas, the possibility of incomplete depositsintheburnerpartsoronorificecaps.Gradualchanges
combustion could be suspected. Without the hydrogen test, in the record from normal values may indicate a failure to
there might be some tendency to make adjustments to com- replenish the water in the reserve tank or may show the
pensate in another way for the low reading. This is obviously existence of obstructions on the overflow weir.
undesirable. 9.1.1.1 SMART-CAL—The paper in the printer should be
checked weekly. It may be necessary to correct the time. If
NOTE 13—Use the manufacturer’s instruction manual for the hydrogen
alarm lights such as “high,” “low,” “max deviation,” or “flame
test. This test is considered satisfactory if the reading agrees with the
out” are activated, the operator will check the tank unit for
theoretical value within 0.3%.
water level, flame out, dirty overflow weir, restricted combus-
9. Operation and Checking of Apparatus
tion air flow, defective burner parts, and so forth.
9.1 The recording calorimeter is designed for continuous 9.1.2 Tank Unit—To avoid contamination of the air in the
operation and, as a precision instrument, it should receive roomwithcombustiblegas,takecaretoen
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