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 pressure need not be measured precisely, as the concentration of nitrogen in the mixture thus prepared must be determined by comparison to nitrogen in the reference standard.
Open the valve on the L cylinder, then open the valve on Cyhnder B, which w i l l result in the transfer of nearly all of the contents of Cyhnder B into the L cylinder. The well type inherendy offers better precision and is preferred when calibrating w i t h pure components.
Obtain a corresponding response on the reference standard. Methane should be in a 1-L cyHnder at MPa atm pressure.
40 CFR 600.011 – Incorporation by reference.
A value of may be used for the molecular weight of the octanes and heavier reverse-flow peak. The percent nitrogen is multiplied by 0. Make calculations on ethane and heavier components in the same manner as for the complete analysis method. Measure areas of all peaks eluted after n-pentane.
Flush the connection with the n-pentane by loosening the fitting at d1495-03 valve on Cylinder A. Chromatographs are not truly linear over wide concentration ranges and linearity should be established over the range of interest.
Enter the sample, and backflush heavy components when appropriate. Daily calibrations are recommended. This trouble has been experienced with some inlet systems even when clean and with the specified sample loop size. Weigh Cylinder A after each addition to obtain the weight of the component added. Obtain a corresponding chromatogram of the reference standard. The reverse flow area, and the pentanes peaks used for comparison, should be measured by the same method.
Adjust the operating conditions and allow the chromatograph to stabilize.
The surface effect of d1954-03 diameter tubing acts as a separating column and must not be used in the sampling and entering system when components heavier than pentanes are to be determined.
The U-tube type is useful, since i t permits filling the sample loop w i t h up to two atmospheres of sample pressure, thus extending the range of all components. Copper, brass, and other copper-bearing alloys are unacceptable.
40 CFR – Incorporation by reference. | US Law | LII / Legal Information Institute
Connect Cylinder B to the L cylinder with as short a clean, small-diameter connector as possible. Usually 1 m of 6-mm tubing packed w ith to mesh molecular sieves is adequate, i f changed w ith each cylinder o f carrier gas. 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.
The amount of purging required must be astj and verified for each instrument. The separation should be completed within 40 min, including reversal of flow after n-pentane to yield a group response for hexanes and heavier components. Run a sample of the standard d1945-0 at kPa mm H g pressure and obtain aztm for methane and nitrogen. Also measure the areas of both pentane peaks on the sample chromatogram, and adjust all measured areas to the same attenuation basis.
Keep the system short and the drier small to minimize the purging required. Die bond process intro Other natoral gas d1945–03 do exhibit a significant compressibility at pressures less than atmospheric. Users of this standard are expressly advised that determination of the validity wstm any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. 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.
Weigh Cylinder B after aztm addition to obtain the weight of the component added. Significance and Use 4. Connect Cylinder A to the evacuated L cylinder with as short a clean, small-diameter connector as possible. Separation of carbon dioxide must be sufficient so that a 0.
I f hydrogen is present, use aluminum, stainless steel, or other materials inert to hydrogen sulfide for v1945-03 cylinder, valves, lines, and connections. This component is present i n the daily calibration standard and linearity is assured from previous d194-503.
Convert the weight percent to mole percent. 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. Concentration of these components has been observed to occur in a number of cases because of collection of heavier components in the sample loop during purging of the aastm.
Transfer the methane to the L cylinder until the pressure equalizes. Moisture on the column w i l l enlarge the reverse flow peak. The operating conditions, including columns, are also typical and are subject to optimization by competent personnel.
This contamination can be minimized by such techniques as purging with inert gas, heating the sample loop, using a vacuum system, or other such effective means. Also, the richer the gas, the worse the problem.