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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NOTE 6—Most modem chromatographs have valve ovens that can be temperature controlled. Last prewous edition approved in as However, it is necessary to know the average molecular weight of the pentanes and heavier components.
Permission rights to photocopy the standard may also be secured from the ASTM website www. Make calculations in the same manner as for the complete analysis method.
Do not rely on oxygen standards that have been prepared for more than a few days. This small sample size is necessary to obtain a linear detector response for methane. Select a sample size in accordance with 8. The values given in parentheses asgm mathematical conversions to SI units that are provided for information only and are not considered standard. The test method can be used on any gas chromatograph using a thermal d1945-0 or thermistor detector.
Weigh the 1-L cylinder to determine the weight of methane transferred. Enter the sample and obtain a response through methane Note 5. The surface effect of small diameter tubing acts as a separating column and must not be used in the sampling and entering system when components heavier than adtm are to be determined.
Keep the system short and the drier small to minimize the purging required.
The higher the temperature the shorter the equilibration time approximately 2 h for small sample containers of mL or less. Then admit samples of pure ethane cind propane at kPa mm Hg absolute pressure, and butanes, pentanes, and carbon dioxide at 5-kPa mm H g absolute pressure. Enter a 1- to 5-mL sample and record the response for helium, followed by hydrogen, which will be just ahead of oxygen Note 5.
I f this condition cannot be remedied by adjustment o f the gain, check the electronics in the recorder. The percent nitrogen aetm multiplied by 0.
ASTM D – 03 Standard Test Method for Analysis of Natural Gas by Gas Chromatography
The major component methane is used as the balance gas and may fall below the expected concentration. The fewer components eliminates dew point problems, reactivity, is more accurate and can be blended at a higher pressure. W h e n a planimeter is used, carefully make several tracings and use the average. The reverse flow area, and the pentanes peaks used for comparison, should be measured by the same method.
However, short and long partition columns provide the flexibility of three partition column lengths, by using them either singly or in series. Warning—Some components, such as carbon dioxide, hydrogen sulfide, and hexanes and higher hydrocarbons, may be partially or completely removed by the water. Either the average of the two consecutive checks, or the latest check agreeing within the repeatability limits of the previous check on each component may be used as the reference standard for all subsequent runs until there is a change in instrument operating conditions.
Convert the weight percent to mole percent. Moisture on the column w i l l enlarge the reverse flow peak. Correct each peak area to the mol basis by dividing each peak area by the molecular weight of the component.
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. D – 03 Reapp. A level baseline should be quickly attained in either flow direction i f the column is clean. Procedure for Linearity Check: 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.
Close the valve to the vacuum source and carefully meter the fuel-gas sample from the sample cylinder until the sample loop is filled to the desired pressure, as indicated on the manometer see Fig. Flush the connection with the n-pentane by loosening the fitting at the valve on Cylinder A.
40 CFR 600.011 – Incorporation by reference.
The detector temperature shall be equal to or greater than the maximum column temperature. They must contain known percents of the components, except oxygen Note 5that are to be determined in the unknown sample.
Inject the sample into the chromatograph. Mount as required to dry the sample. Replace the drying agent after about one astk of the material has become spent. The sum of the original values should not differ from W i t h either type manometer the m m scale can be read more accurately than the inch scale. Significance and Use 4. Connect Cylinder A to a cylinder of pure n-pentane with a metal f1945-03 of calculated length to contain approximately the amount of n-pentane to be added.
Obtain a corresponding response astmm the reference standard.