ASTM D1826-94(2017)

Standard Test Method for Calorific (Heating) Value of Gases in Natural Gas Range by Continuous Recording Calorimeter

SIGNIFICANCE AND USE
4.1 This test method provides an accurate and reliable method to measure the total calorific value of a fuel gas, on a continuous basis, which is used for regulatory compliance, custody transfer, and process control.
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 ft3.  
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 X1  
Operating Precautions  
Appendix 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.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2017
• ICS: 17.200.10 - Heat. Calorimetry
• ICS: 75.160.30 - Gaseous fuels
• Technical Committee: D03 - Gaseous Fuels
• Drafting Committee: D03.03 - Determination of Heating Value and Relative Density of Gaseous Fuels

Relations

• Replaces: ASTM D1826-94(2010) - Standard Test Method for Calorific (Heating) Value of Gases in Natural Gas Range by Continuous Recording Calorimeter
• Effective Date: 01-Apr-2017
• Referred By: ASTM D7314-21 - Standard Practice for Determination of the Heating Value of Gaseous Fuels using Calorimetry and On-line/At-line Sampling
• Effective Date: 01-Apr-2017
• Referred By: ASTM D4891-13(2018) - Standard Test Method for Heating Value of Gases in Natural Gas and Flare Gases Range by Stoichiometric Combustion
• Effective Date: 01-Apr-2017

Overview

ASTM D1826-94(2017), Standard Test Method for Calorific (Heating) Value of Gases in Natural Gas Range by Continuous Recording Calorimeter, provides a reliable and accurate procedure to determine the total calorific or heating value of fuel gases, specifically within the natural gas range (900 to 1200 Btu/standard cubic foot). Developed and maintained by ASTM International, this method employs a continuous recording calorimeter to monitor the heating value on an ongoing basis, making it especially suitable for applications where real-time data is essential.

This test method is frequently used for:

• Regulatory compliance
• Custody transfer of natural gas
• Process control within the gas industry

By providing ongoing, precise calorific value measurement, it enables operators and stakeholders to ensure the quality and consistency of fuel gases being produced, transported, or sold.

Key Topics

• Continuous Recording Calorimeter: Instrument setup and operation including tank unit, recording unit, and environmental controls.
• Sample and Calibration Procedures: Methods for preparing gas samples, calibrating the calorimeter with reference gases like standard methane and hydrogen, and ongoing maintenance.
• Air-Gas Ratio and Cold Balance Tests: Procedures to ensure measurement accuracy by validating meter alignment and circuit calibration.
• Compensation of Influencing Factors: Adjustments for variables such as tank temperature, barometric pressure, and vapor pressure to maintain precise BTU or heating value readings.
• Measurement Basis: Detailed definitions for referenced gas conditions (pressure, temperature, humidity) and calculation methods for alternate measurement bases.
• Precision and Reproducibility: Guidelines to maintain high reliability over prolonged use and methods to verify ongoing instrument performance.

Applications

The ASTM D1826-94(2017) standard is highly valuable in various settings within the energy and utilities sectors, including:

• Natural Gas Processing Plants: For continuous monitoring and controlling of product quality in real time, supporting both efficiency and compliance.
• Pipeline Operations: To ensure accurate custody transfer measurements during gas trading and distribution, protecting both buyers and sellers.
• Utility Regulatory Compliance: Satisfying legal or contractual requirements by providing transparent, traceable records of calorific value.
• Research and Development: In testing laboratories focused on the analysis or improvement of gaseous fuels.
• Process Control Automation: Integrating calorimeter data into digital control systems for automated adjustment of blending, processing, or billing operations.

These applications rely on the standard’s ability to provide on-line, automatic, and highly precise results, which improves decision-making and supports fair commerce.

Related Standards

For a broader understanding of gaseous fuel measurement and quality assurance, consider the following related ASTM International standards:

• ASTM D1945: Standard Test Method for Analysis of Natural Gas by Gas Chromatography
• ASTM D3588: Standard Practice for Calculating Heat Value, Compressibility Factor, and Relative Density of Gaseous Fuels
• ASTM D3612: Standard Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas Chromatography

These complementary standards help ensure comprehensive measurement, analysis, and reporting throughout the natural gas value chain.

Practical Value

ASTM D1826-94(2017) is critical for organizations committed to accurate fuel gas measurement. It helps deliver consistent calorific value data essential for regulatory, commercial, and operational integrity, minimizing risks and ensuring fair and efficient market transactions in the natural gas industry.

Keywords: calorific value, natural gas, continuous recording calorimeter, ASTM D1826, heating value, fuel gas analysis, BTU measurement, regulatory compliance, custody transfer, process control.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:D1826 −94 (Reapproved 2017)
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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Terminology
1.1 This test method covers the determination with the 2.1 Definitions of Terms Specific to This Standard:
continuous recording calorimeter (Note 1) of the total calorific 2.1.1 The most important terms used in connection with the
(heating) value of fuel gas produced or sold in the natural gas
determination of the calorific value of gaseous fuels in record-
range from 900 to 1200 Btu/standard ft . ing calorimetry are as follows:
2.1.2 British Thermal Unit, or Btu—is the defined Interna-
NOTE 1—An extensive investigation of the accuracy of the Cutler-
tional Tables British thermal unit (symbol Btu).
Hammer recording gas calorimeter, when used with gases of high heating
value, was made by the National Bureau of Standards in 1957 under a
NOTE 2—The defining relationships are:
research project sponsored by the American Gas Association.
−1 −1
(a) 1 Btu·lb =2.326 J·g (exact)
1.2 The subjects covered in this test method appear in the (b) 1 lb=453.59237 g (exact).
By these relationships, 1 Btu = 1 055.05585262 J (exact). For most
following sections:
purposes, the value rounded to 1 Btu = 1 055.056 J is adequate.
Sections
2.1.3 combustion air—airusedforcombustion,atotalofthe
Air-Gas Ratio Test 11
Apparatus 5
portion mixed with the gas as primary air and the air supplied
Basis of Measurement 14
around the burner tube as secondary air (theoretical air plus
Cold Balance Test 10
excess air).
Compensation of Complicating Factors 13
Condition of Gas Sample 7
2.1.4 flue gases—the products, of combustion remaining in
Definitions 2
Installation of Apparatus 6 the gaseous state, together with any excess air.
Maintenance Appendix X1
2.1.5 heat-absorbing air—the heat exchange medium used
Operating Precautions Appendix X2
Operation and Checking of Apparatus 9
to absorb the heat of combustion derived from the burning of
Precision 15
gaseous fuel.
Scope 1
Significance and Use 4
2.1.6 saturated basis—the expressed total calorific value of
Standardization of Calorimeter 12
a gas when it is saturated with water vapor at standard
Standardization, Preliminary, of Calorimeter by Hydrogen 8
temperature and pressure; 1 ft of this gas is equivalent in dry
Summary of Test Method 3
gascontentto0.9826ft ofdrygasatthestandardtemperature
1.3 This standard does not purport to address all of the
of 60°F and standard pressure of 14.73 psia.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
NOTE 3—The definitions given in 2.1.6 and 2.1.10 are for total calorific
priate safety and health practices and determine the applica- (heating) values per standard cubic foot of gas. The definitions corre-
sponding to any other unit quantity of gas are obtained by substituting the
bility of regulatory limitations prior to use.
name of the desired unit in place of the term “standard cubic foot” in the
1.4 This international standard was developed in accor-
definitions. Methods of calculating calorific (heating) values per cubic
dance with internationally recognized principles on standard-
foot of gas under any desired conditions of pressure, temperature, and
ization established in the Decision on Principles for the
water vapor content are specified in Section 14.
Development of International Standards, Guides and Recom-
2.1.7 standard cubic foot of gas—the quantity of any gas
mendations issued by the World Trade Organization Technical
that at standard temperature and under standard pressure will
Barriers to Trade (TBT) Committee. 3
fill a space of 1 ft when in equilibrium with liquid water.
2.1.8 standard pressure—is 14.73 psia.
ThistestmethodisunderthejurisdictionofASTMCommitteeD03onGaseous
NOTE 4—This is the pressure base adopted by the American National
Fuels and is the direct responsibility of Subcommittee D03.03 on Determination of
Standards Institute in 1969 (Z132.1). According to Dalton’s law, this is
Heating Value and Relative Density of Gaseous Fuels.
equivalent to stating that the partial pressure of the gas is:
Current edition approved April 1, 2017. Published April 2017. Originally
approved in 1961. Last previous edition approved in 2010 as D1826–94(2010). 14.73−0.25636=14.47364 psia
DOI: 10.1520/D1826-94R17. where 0.25636 is the vapor pressure of water in psia at 60°F.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1826−94 (2017)
2.1.9 standard temperature—60°F, based on the interna- 5. Apparatus
tional practical temperature scale of 1968.
5.1 The recording calorimeter (Note 5) consists of two
2.1.10 total calorific value (gross heating value, higher
major units; the tank unit or calorimeter proper, Fig. 1, Fig. 2,
heating value)—of a gas is the number of British thermal units
and Fig. 3, in which the heating value of the test gas sample is
evolved by the complete combustion at constant pressure of
measured; and the recording unit which translates the heat
one standard cubic foot of gas with air, the temperature of the
measurements into an indication of calorific (heating) value
gas, air, and products of combustion being 60°F, and all the
and records it graphically on a strip chart recorder or digitally
water formed by the combustion reaction being condensed to
if the new SMART-CAL is used (Note 6).
the liquid state.
NOTE 5—The previous specified pressure base was the absolute
pressure of a column of pure mercury 30 in. in height at 32°F and under
3. Summary of Test Method
standard gravity (32.174 ft/s ). This is equivalent to 14.7346 psia.
NOTE 6—Refer to specific manufacturer’s manual for pictures of the
3.1 The heating value is determined by imparting all of the
recorder or the SMART-CAL, a digital indicating or printing device,
heat obtained from the combustion of the test gas to a stream
currently used on new or retrofitted calorimeters.
of air and measuring the rise in temperature of the air. The
6. Installation of Apparatus
streams of test gas and heat absorbing air are maintained in
fixed volumetric proportion to each other by metering devices
6.1 To secure the precise results that are possible with the
similar to the ordinary wet test meters geared together and
recording calorimeter, it is important that the instrument be
driven from a common electric motor.The meters are mounted
installed so that the surrounding conditions will not introduce
in a tank of water, the level of which is maintained and the
errors. In general, more precise results will be secured when a
temperature of which determines the temperature of the enter-
narrow range is maintained on the various conditions of the
ing gas and air.
calorimeter environment.
3.2 The flue gas resulting from combustion of the gas
6.2 Calorimeter Room—A typical installation of a single
(combustion products plus excess combustion air) is kept
recording calorimeter is shown in Fig. 4. The detailed require-
separate from the heat-absorbing air and is cooled to a few
ments for the calorimeter room are given in Table 1.
degrees above the initial temperature of gas and air. The water
NOTE 7—Adetailed discussion of these requirements is included in the
formed in the combustion is practically all condensed to the
latest edition of the manufacturer’s instruction book covering the record-
liquidstate.Consequently,thetemperatureriseproducedinthe
ing calorimeter. The information can be applied to all models of the
heat-absorbing air is directly proportional to the heating value instrument.
NOTE 8—The dimensions shown in Fig. 4 are for the latest model
of the gas. Since all the heat from the combustion of the test
calorimeter.
gas sample, including the latent heat of vaporization of the
6.3 Gas Connection—Locate the sample line that brings the
water vapor formed in the combustion, is imparted to the
heat-absorbing air, the calorimeter makes a direct determina- gas to be tested to the calorimeter tank unit so that the heating
valueisactuallyrepresentativeoftheconditionsexistinginthe
tionoftotalheatingvalue.Thetemperatureriseismeasuredby
nickel resistance thermometers and is translated into Btu per main gas line. Keep the sample line time lag as small as
possible by (1) locating the calorimeter tank unit close to the
standard cubic foot.
sample point, (2) running the sample line of small size pipe
4. Significance and Use
(Note 9), and (3) operating the sample line at low pressure.
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
continuous basis, which is used for regulatory compliance,
NOTE 9—Time lag may be calculated on the basis that the calorimeter
custody transfer, and process control. uses about 1.2 ft /h.
FIG. 1 Calorimeter—Schematic Flow Diagram
D1826−94 (2017)
FIG. 2 Calorimeter—Layout Diagram
performance, it will be necessary to use distilled or demineralized water
6.4 Electrical Wiring—The four leads for the resistance
withapHof7.
thermometers between either the recorder or the Smart-Cal
NOTE 12—For actual test instructions and other information, see the
junction box and the tank unit shall be of No. 12 gage,
appropriate instruction book provided by the manufacturer.
insulated, solid copper wire without joints. Run in a separate
rigid metal conduit which is grounded and contains no other
6.6 Recorder Installation—Install the recorder so that the
leads (Note 10). Power circuit wiring should be No. 14 gage,
instrument is reasonably free from mechanical vibration. This
insulated, solid or stranded, copper wire. Provide the supply
is particularly important for those models in which a
line with a suitably fused disconnect switch. For the model
suspension-type galvanometer is used.
using an electronic recorder, it is essential that a suitable
ground connection be made at both the recorder and the tank
7. Condition of Gas Sample
unit. Details are given in the manufacturer’s instructions.
7.1 Physical Contamination—The gas sample should be
NOTE 10—Where outdoor or underground wiring must be used, special
free of dust, water, and other entrained solids. If experience
care should be exercised to protect the terminals of the cables from
indicates that the foreign materials can enter the sample line,
moisture to prevent grounds in the measuring circuit.
install a suitable sample line filter. To avoid any problems in
6.5 Initial Installation—When the calorimeter is first
the line from water accumulation, pitch the line to a low point
installed, fill the tank unit with water (Note 11) and adjust it to
and provide a drip leg.
a temperature that is 2 to 5°F below the normal room
temperature. Allow the unit to operate at least 24 h before
7.2 Chemical Contamination—The sample line should be
performing the detailed calibration tests.
practically free from hydrogen sulfide. A small, low-capacity
NOTE 11—The water may be ordinary tap water supplied by most
purifier can be constructed using iron oxide on wood shavings
municipalities.If,however,itisfoundthatexcessivequantitiesofdeposits
as the purifying material. The time lag in the purifier adds to
and sludge are formed in short duration which interfere with satisfactory
D1826−94 (2017)
FIG. 3 Calorimeter Combustion Chamber
NOTE 1—For each additional calorimeter at least 50% additional space is required; for example, for two calorimeters the room should be 12 by 18
ft inside; for three calorimeters 15 by 18 ft.
FIG. 4Calorimeter Room
D1826−94 (2017)
TABLE 1 Calorimeter Room Requirements
Detail Requirements
Space 1000 ft, min.
Ceiling height 8 ft, min.
Side wall widths 10 and 13 ft, min.
Windows One, on side normally away from sun (in northern hemisphere, the northern side).
Doors One, wth 3-ft opening, not in window wall. A door check is desirable.
Ventilation Natural ventilation using ceiling vent and a vent at floor level. Both should be located away from the tank unit.
Tank location The tank unit should be in a draft-free location with respect to heating and cooling units and natural ventilation.
Heating and cooling Controlled in the range 60 to 75°F with a variation of not more than 2.5°F from the set point.
Foundation floor The calorimeter should remain level at all times. Design for 3000-lb static and dynamic load. The tank feet should be on load
bearing parts of the floor.
Lighting No direct sunlight permitted on calorimeter tank unit.
Condition of air Essentially free from dust and absolutely free from any combustible gas for both measurement accuracy and safety. Trace
hydrocarbons can be removed from combustion air using a Hoskins furnace and a combustion air meter hood.
Vibration No vibrations or shocks shall be transmitted to the tank unit.
Water Pure pH-7 clean water shall be available for filling the tank and replenishing the reserve tank.
Power supply 115 V, 1 phase, 60 Hz, 1000 W for small motors. Lighting, heating, and cooling in addition.
1 1
Gas supply Sample pipe shall be ⁄4-in. tubing. Pressure shall be cut at the pipeline to 1 ⁄2 to 2 psig for minimum time lag. Pressure at the
calorimeter shall be 6 to 30 in. w.c.
Water supply and drain Desirable but not essential.
Radiation Tank unit shall be shielded from any hot radiation surfaces.
Safety It should be remembered that the calorimeter has open flames. Natural ventilation is sufficient in nonhazardous locations and
where only the aforementioned ⁄4-in. tubing service for natural gas at 1 psig is used. Hydrocarbon vapor detectors and purging
means should be considered for installations where location can be hazardous, where higher pressure gas is present, or where
gases heavier than air are involved. In all installations, lighting installations should be suitable for Division I, and incoming power
from underground services should have sealoffs.
the sample line time lag so that the purifier should be of small 9. Operation and Checking of Apparatus
capacity. A design that will purify about 3 ft of gas/h will be
9.1 The recording calorimeter is designed for continuous
satisfactory.
operation and, as a precision instrument, it should receive
regular inspection. Recording the results of tests, the replace-
8. Preliminary Standardization of Calorimeter by
mentofanyparts,andtheestablishmentofaregularinspection
Hydrogen
will ensure that the high degree of precision attainable will be
8.1 The use of preliminary standardization by hydrogen test maintained. The manufacturer’s appropriate instruction book
gasbeforetheuseofstandardmethaneatthetimeoftheinitial
givesdetailsoftheprocedureforoperatingtheinstrument.The
installation or after any complete major overhaul of the tank following points should be checked periodically:
unit and recorder is required, because of the following factors:
9.1.1 Recorder—Check the operation of the recorder at
8.1.1 Because of the low density of hydrogen, the presence
regular intervals to be sure that the chart is set at the proper
ofanyleaksinthesystemfromthegasmetertotheburnerwill time and that the pen is making a satisfactory line. Examina-
result in a definite low reading. This situation should certainly
tions of the chart record will aid in avoiding certain operating
be considered on the initial installation and whenever the gas problems since the record will show if undesirable conditions
meterassemblyhasbeendismantledforinspectionorcleaning.
develop. For example, an irregular chart may be the result of
depositsintheburnerpartsoronorificecaps.Gradualchanges
8.1.2 The hydrogen test gives another cross-check of the
slide wire and thermometer calibration at a different point on in the record from normal values may indicate a failure to
replenish the water in the reserve tank or may show the
the scale of the instrument. A satisfactory hydrogen test gives
additional assurance that no error exists in this part of the existence of obstructions on the overflow weir.
instrument.
9.1.1.1 SMART-CAL—The paper in the printer should be
8.1.3 There is practically no possibility of incomplete com- checked weekly. It may be necessary to correct the time. If
bustion on the hydrogen test. Therefore, a satisfactory hydro- alarm lights such as “high,” “low,” “max deviation,” or “flame
gen result gives assurance that, with the proper heat input, the out” are activated, the operator will check the tank unit for
correct calorific value reading will be secured. If a satisfactory water level, flame out, dirty overflow weir, restricted combus-
hydrogen test has been secured and a low reading has been tion air flow, defective burner parts, and so forth.
obtained on the standard gas, the possibility of incomplete
9.1.2 Tank Unit—To avoid contamination of the air in the
combustion could be suspected. Without the hydrogen test,
roomwithcombustiblegas,takecaretoensurethatthebleeder
there might be some tendency to make adjustments to com-
burner remains lighted at all times. For unattended locations, a
pensate in another way for the low reading. This is obviously
thermostatically operated shutoff valve that closes upon failure
undesirable.
of the bleeder flame is normally provided. Regular inspection
will indicate the necessity of replenishing the water in the
NOTE 13—Use the manufacturer’s instruction manual for the hydrogen
reservetankandthusensuremaintenanceoftheproperlevelin
test. This test is considered satisfactory if the reading agrees with the
theoretical value within 0.3%. themaintank.Thepresenceofanyforeignmaterialeitherinor
D1826−94 (2017)
on the water can be avoided by regular examination. This will 10.2.2 The cold balance and span adjustments are made
prevent incorrect overflow weir operation. Periodic examina- when the SMART-CAL is in the calibration mode. Using the
tion of the thermometers and the burner parts will avoid errors keyboard, the operator should activate the low-range display.
in reading which could be caused by deterioration of any of This value is adjusted using the cold balance screw on front.
these parts. Then the high-range display is activated. It is then set to the
correctvalueusingthespanscrewonthetopoftheinstrument.
10. Procedure for Cold Balance Test
The correct low- and high-range values are specified on a
calibration plate on the front of the instrument. These values
10.1 For the Recorder When Used:
are a function of the heating value range, the thermometer pair
10.1.1 The object of the cold balance test is to check the
used, and the basis of measurement.
complete temperature-measuring circuit. It is equivalent to the
calorimeter measuring a gas with zero heating value. For this
11. Procedure for Air-Gas Ratio Test
test,observethesameprecautionsandcarethatarerequiredfor
thecalorimeterinnormaluse.Theoveralltimeoftestshallnot
11.1 Theobjectoftheair-gasratiotestistoensurethefixed
be less than 1 h. predetermined volume relation between the output of the gas
10.1.2 If the cold balance is consistent within the range of meter and that of the heat-absorbing air meter. This volume
the balancing rheostat (only small variations occurring from ratio is a basic factor in the accuracy of the calorimeter.
one test to another), the thermometer leads and resistance
11.2 The room temperature shall be reasonably constant at
elements in the circuit are in satisfactory condition.
the normal controlled value during the test.
10.1.3 The rheostat provides a small amount of
...