EPA Method 25C Determination Of Nonmethane Organic Compounds (Nmoc) In Landfill Gases
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ID： |
5F2FDE40E4304A30BEA18E78FD2C8317 |
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文件大小(MB)： |
0.06 |
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页数： |
16 |
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文件格式： |
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日期： |
2000-2-12 |
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文本摘录（文本识别可能有误，但文件阅览显示及打印正常，pdf文件可进行文字搜索定位）：
1268,METHOD 25C - DETERMINATION OF NONMETHANE ORGANIC,COMPOUNDS (NMOC) IN LANDFILL GASES,NOTE: This method does not include all of the,specifications (e.g., equipment and supplies) and procedures,(e.g., sampling and analytical) essential to its,performance. Some material is incorporated by reference,from other methods in this part. Therefore, to obtain,reliable results, persons using this method should also have,a thorough knowledge of EPA Method 25.,1.0 Scope and Application.,1.1 Analytes.,Analyte CAS No.,Nonmethane organic compounds,(NMOC),No CAS number assigned,1.2 Applicability. This method is applicable to the,sampling and measurement of NMOC as carbon in landfill gases,(LFG).,1.3 Data Quality Objectives. Adherence to the,requirements of this method will enhance the quality of the,data obtained from air pollutant sampling methods.,2.0 Summary of Method.,2.1 A sample probe that has been perforated at one end,is driven or augured to a depth of 0.9 m (3 ft) below the,bottom of the landfill cover. A sample of the landfill gas,1269,is extracted with an evacuated cylinder. The NMOC content,of the gas is determined by injecting a portion of the gas,into a gas chromatographic column to separate the NMOC from,carbon monoxide (CO), carbon dioxide (CO2), and methane,(CH4); the NMOC are oxidized to CO2, reduced to CH4, and,measured by a flame ionization detector (FID). In this,manner, the variable response of the FID associated with,different types of organics is eliminated.,3.0 Definitions. [Reserved],4.0 Interferences. [Reserved],5.0 Safety.,5.1 Since this method is complex, only experienced,personnel should perform this test. LFG contains methane,therefore explosive mixtures may exist on or near the,landfill. It is advisable to take appropriate safety,precautions when testing landfills, such as refraining from,smoking and installing explosion-proof equipment.,6.0 Equipment and Supplies.,6.1 Sample Probe. Stainless steel, with the bottom,third perforated. The sample probe must be capped at the,bottom and must have a threaded cap with a sampling,attachment at the top. The sample probe must be long enough,to go through and extend no less than 0.9 m (3 ft) below the,landfill cover. If the sample probe is to be driven into,1270,the landfill, the bottom cap should be designed to,facilitate driving the probe into the landfill.,6.2 Sampling Train.,6.2.1 Rotameter with Flow Control Valve. Capable of,measuring a sample flow rate of 100 ± 10 ml/min. The,control valve must be made of stainless steel.,6.2.2 Sampling Valve. Stainless steel.,6.2.3 Pressure Gauge. U-tube mercury manometer, or,equivalent, capable of measuring pressure to within 1 mm Hg,(0.5 in H20) in the range of 0 to 1,100 mm Hg (0 to 590 in,H2O).,6.2.4 Sample Tank. Stainless steel or aluminum,cylinder, equipped with a stainless steel sample tank valve.,6.3 Vacuum Pump. Capable of evacuating to an absolute,pressure of 10 mm Hg (5.4 in H2O).,6.4 Purging Pump. Portable, explosion proof, and,suitable for sampling NMOC.,6.5 Pilot Probe Procedure. The following are needed,only if the tester chooses to use the procedure described in,Section 8.2.1.,6.5.1 Pilot Probe. Tubing of sufficient strength to,withstand being driven into the landfill by a post driver,and an outside diameter of at least 6 mm (0.25 in.) smaller,than the sample probe. The pilot probe shall be capped on,1271,both ends and long enough to go through the landfill cover,and extend no less than 0.9 m (3 ft) into the landfill.,6.5.2 Post Driver and Compressor. Capable of driving,the pilot probe and the sampling probe into the landfill.,The Kitty Hawk portable post driver has been found to be,acceptable.,6.6 Auger Procedure. The following are needed only if,the tester chooses to use the procedure described in,Section 8.2.2.,6.6.1 Auger. Capable of drilling through the landfill,cover and to a depth of no less than 0.9 m (3 ft) into the,landfill.,6.6.2 Pea Gravel.,6.6.3 Bentonite.,6.7 NMOC Analyzer, Barometer, Thermometer, and,Syringes. Same as in Sections 6.3.1, 6.3.2, 6.33, and,6.2.10, respectively, of Method 25.,7.0 Reagents and Standards.,7.1 NMOC Analysis. Same as in Method 25, Section 7.2.,7.2 Calibration. Same as in Method 25, Section 7.4,except omit Section 7.4.3.,7.3 Quality Assurance Audit Samples.,7.3.1 It is recommended, but not required, that a,performance audit sample be analyzed in conjunction with the,1272,field samples. The audit sample should be in a suitable,sample matrix at a concentration similar to the actual field,samples.,7.3.2 When making compliance determinations, and upon,availability, audit samples may be obtained from the,appropriate EPA Region……
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