ASTM D1945-03 PDF
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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The air must be either entered at d194503 accurately measured reduced pressure, or from a helium-diluted mixture. Avoid introduction of liquids into the sample system. Close the cylinder valves, disconnect, and weigh Cylinder B to obtain the weight of the mixture that was not transferred to the L cylinder.
Connect Cylinder A to a cylinder of pure n-pentane with a metal connection of calculated length to contain approximately the amount of n-pentane to be added. The surface effect of ast diameter tubing acts as a separating column and must not be used in the sampling and entering system when components heavier than pentanes are ashm be determined. Adjust the operating conditions and allow the chromatograph to stabilize. Heated lines may be necessary for high hydrocarbon content samples.
Inject the sample into the chromatograph. The amount of purging required must be established and verified for each instrument. Replace the drying agent after about one half of the material has become spent.
Avoid contact with the skin as much as possible. Run a sample of the standard mixture at kPa mm H g pressure and obtain peaks for methane and nitrogen. If a recorder is used, the recorder pen must return to the baseline between each successive peak. D194-03 1 m of 6-mm tubing packed w ith to mesh molecular sieves is adequate, i f aetm w ith each cylinder o f carrier gas. This flow should quickly r e m m to the same flow rate and the baseline level out.
See Table 2 and Table 3. It is helpful to retain a sample containing some hexanes and heavier for periodic checking. The thermal conductivity detector must be sufficiently sensitive to produce a signal of at aatm 0.
ASTM D – 03 Standard Test Method for Analysis of Natural Gas by Gas Chromatography
Then immediately inject the contents of the loop or mbe into the chromatographic column to avoid infiltration of contaminants. On high sensitivity, this baseline may drift slightiy without harm and it need not frequently be moved back to zero.
Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Either the average of the two consecutive checks, or the latest check agreeing within the repeatability limits of the previous check on each component d19455-03 be used as the reference standard for all subsequent runs until there is a change in instrument operating conditions. Diluted dry air is sstm suitable standard for oxygen and nitrogen see 8.
The width of the chart shall be not less than mm. SuiBcient accuracy can be obtained for the determination of all but the minor constituents by asfm use of this sample size. Likewise, obtain a response on the reference standard for nitrogen and methane.
Open the valve on the L cylinder, then open the valve on Cylinder A.
40 CFR 600.011 – Incorporation by reference.
1d945-03 A smaller loop size should replace the fixed volume loop and 6. It is strongly recommended in the absence of valve ovens to mount the gas samphng valve in the chromatograph oven and operate at the column temperature.
Transfer the methane to the L cylinder until the pressure equalizes. This eliminates the need for a multicomponent standard for daily calibration. Connect Cylinder B to the L cylinder with as short a clean, small-diameter connector as possible. Copper, brass, and other copper-bearing alloys are unacceptable. A l l single-peak determinations and corresponding reference runs w i l l then be made in the same carrier gas flow direction.
Permission rights to photocopy the standard may also be secured from the ASTM website www. A strip-chart recorder w ith an offset d19455-03 is desirable. The preferred material of construction is stainless steel. The higher the temperature the shorter the equilibration time approximately 2 h for small sample containers of mL or less.
The sample-entry system must be vacuum tight. When enlargement of the heavy end peaks is noted, thoroughly clean the sampling valve and loop with acetone. In multicolumn apphcations, it is preferred to use front-end backflush of the heavy ends.
I f the dew point is unknown, heat above the sampling temperature.