ASTM D, D, and EPA 3C are used for the analysis of permanent gases (also called fixed gases) and light hydrocarbons at the percentage level in all. (A) Hydrocarbon compounds containing between one and five atoms of carbon plus benzene using ASTM D–03 (Reapproved ) (incorporated by. American Standards Testing & Materials (ASTM). D Standard D 03 Standard Test Method for Analysis of Natural Gas by Gas. Chromatography.
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This component is present i n the daily calibration standard and linearity is assured from previous tests. The sample-entry system must be d194-03 tight. In multicolumn apphcations, it is preferred to use front-end backflush of the heavy ends. The thermal d19445-03 detector must be sufficiently sensitive to produce a signal of at least 0.
To make this determination, enter a 5-mL sample into the short column and reverse the carrier gas after the separation d1945-30 n-heptane. Moisture on the column w i l l enlarge the reverse flow peak. Also measure the areas of both pentane peaks on the sample chromatogram, and adjust all measured areas to the same attenuation basis.
The slope a, can be calculated by: The measured area should be corrected by using the average molecular weights of the entire reverse-flow components for the value of A.
Replace the drying agent after about one half of the material has become spent. It is permissible to use d19445-03 response factor for oxygen that is relative to a stable constituent.
The oven temperature shall not exceed the recommended temperature limit for the materials in the column. However, short and long partition columns provide the flexibility of three partition column lengths, by using them either singly or in series.
This contamination can be minimized by such techniques as purging sstm inert gas, heating the sample loop, using a vacuum system, or other such effective means. Separation of carbon dioxide must be sufficient so that a 0. Samples w i t h up to one atmosphere o f pressure can be entered. Weigh the 1-L cylinder to determine the astj of methane transferred.
Copper and copper-bearing alloys are unacceptable. Obtain a corresponding response on a reference standard containing suitable concentrations of helium and hydrogen see Fig.
Obtain a corresponding response on ast, reference standard. For these components, a mixture with nitrogen or methane can be used to establish a partial pressure that can extend the total pressure to kPa mm Hg. SuiBcient accuracy can be obtained for the determination of all but the minor constituents by r1945-03 use of this sample size. The relationship is independent of temperature, sample size, and carrier gas flow atm.
Maintain all samples above the hydrocarbon dew point. This eliminates the need for a multicomponent standard for daily calibration. Copper, vinyl, or rubber connections are not acceptable. The test method can be used on any gas chromatograph using a thermal conductivity or thermistor detector.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn.
ASTM D – 03 Standard Test Method for Analysis of Natural Gas by Gas Chromatography
The sample size must not exceed 0. Evacuate mL Cyhnder A, and obtain its true weight. The detector temperature shall be equal to or greater than the maximum column temperature. The fixed loop or section shall be so constructed that the total volume, including dead space, shall not normally exceed 0.
Transfer the methane to the L cylinder until the pressure equalizes. Also, the richer the gas, the worse the problem.
40 CFR 600.011 – Incorporation by reference.
They must contain known percents of the components, except oxygen Note 5that are to be determined in the unknown sample. When enlargement of the heavy end peaks is noted, thoroughly clean the sampling valve and d1945-0 with acetone. Correct each peak area to the mol basis by dividing each peak area by the molecular weight of asgm component.
Asym high sensitivity, this baseline may drift slightiy without harm and it need not frequently be moved back to zero. I f i n doubt about the composition, check the n-pentane and isopentane values w ith pure components by the procedure prescribed in Annex A 2. Although a strip-chart recorder is not required when using electronic integration, it is highly desirable for evaluation of instrument performance.
Keep the system short and the drier small to minimize the purging required. The concentration of a component in the reference standard gas should not be less than one half nor more than twice the concentration of the corresponding component in the test gas. Summary of Test Method 3. Obtain a corresponding chromatogram of the reference standard. The purity of the carrier gas may be improved by flowing the carrier gas through selective filters prior to adtm entry into the chromatograph.
Aastm instance, propane can be the reference component for the butanes and pentanes i f propane is separated on the same column in the same sequence as the butanes and pentanes.
Ethane can be the reference component for carbon dioxide i f it elutes i n the same sequence as carbon dioxide. Then immediately inject the contents of the loop or mbe into the chromatographic column to avoid infiltration of contaminants.
Connect Cylinder A to the evacuated L cylinder with as short a clean, small-diameter connector as possible. I f the dew point is unknown, heat above the sampling temperature.
Disconnect and weigh Cylinder A to obtain the weight of n-pentane added. A number in parentheses indicates the year of last reapproval. Measure the peak heights of ethane through? D o not use a fixed zero line as the baseline, but use the actual observed baseline.