10 องค์ประกอบของวิธีการ Based on US.EPA source sampling methods Method 1: Determination of Sampling PointsMethod 2: Determination of Flow VelocityMethod 3: Determination of MW of Dry AirMethod 4: Determination of Moisture ContentMethod 5: Determination of PM (Isokinetic Sampling)Based on US.EPA source sampling methods
34 Method 4 (cont.’d) ก) วิธีมาตรฐาน ใช้อุปกรณ์ของ Method 5 probe (heatable) made of SS or glasscondenser consists of connected 4 impingers (modified Greenburg-Smith) 2 อัน แรกมีน้ำกลั่น, ว่าง, silica gel (6-16 mesh size) with thermometercooling system (ice box)barometerbalance and cylinder
37 Method 4 (cont.’d) การวัด ตำแหน่งเก็บตย.เดียวกับ Mth.1 เติม fix vol. of water in #1&2, ชั่งนน. Silica gel 200 g in #4 record the wt.heated probe 120oC ป้องกันการควบแน่น ใส่ impingers ลงใน ice boxleak check the system --plug the probe and run the pump to P 350 mmHg, dry gas meter should run < m3maintain steady flow +/-10%
38 Method 4 (cont.’d)maintain exit gas from #4 impingers <20oC ลงใน ice boxstart sampling from 1st traverse pointleak check the system --plug the probe and run the pump to the highest P during sampling, dry gas meter should run < m3measure liquid in all 3 impingers, weight 4th impinger
43 Method 4 (cont.’d) ข) วิธีประมาณการ ใช้อุปกรณ์น้อยกว่า Mth. 5 probe (heatable) made of SS or glass2 impingers (30 มล.)dry tube with silica gelcooling system (ice box)barometerbalance and cylinder 25 มล.Rotameter (0-3 ml/m)Note: ดูรูปประกอบ P.m4-11 (ไม่แนะนำเพราะยุ่ง)
57 Method 5 (cont.’d)Diff. pressure guage: use inclined manometer or equivalent 2 sets (measures flow rate in stack and sampling flow rate)filter holder: borosilicate with glass frit (with silicone to prevent leak) นอกจากแก้วอาจเป็นเหล็ก หรือ teflon ก็ได้filter heating system: control 120 +/-14oCcondenser: for determination of humidity of air in stack
58 Method 5 (cont.’d) accessories: Metering system: vacumm gauge, pump, thermometer, dry gas meterbarometer: Patm measurementcondenser: for determination of humidity of air in stackaccessories:filter holder (petri dish)distilled water bottle and acetone
63 Method 5 (cont.’d) Preparation: weight silica gel g. in several bottles (sealed)desiccate filter 20+/-5.6oC at least 24 hrs, weight until mass changed less than 0.5 mg, can heat 105oC 2-3 hrs, then desiccate 2 hrs before weight the filter
64 Method 5 (cont.’d) Preliminary determination: locate sampling point and number of point followed Mth.1determine Ps, Ts, stack velocities followed Mth.2determine dry molecular weight of air in stack followed Mth.3determine humidity in stack followed Mth.4select corrected size nozzle
65 Method 5 (cont.’d) Prepare sampling train Sampling time: each point no less than 2 min. and total sampling volume >0.85 m3 each point requires equal sampling timeselect appropriate sampling probe: may need to sampling both sides (difficult in many places)Prepare sampling trainadd 100 ml distilled water in 1st and 2nd impinger, 3rd left blank, 4th g silica gel (record weight)
66 Method 5 (cont.’d) PM Sampling measuring and marking sampling probe add iceleak check (สำคัญมาก) by pluging the nozzle and run the vacuum pump (380 mmHg), volume should read < m3/min by the meter (if not, find the leak and fix it)PM Samplingsampling rate for isokinetic should +/-10%filter holder should be 120 +/-14oC
67 Method 5 (cont.’d) Heat the probe to required temp. Insert the probe to the 1st point and turn against the flow, cover the inlet to prevent the air getting in.Turn on the pump and start sampling at isokinetic rate (or pressure --- deltaH)If pressure drop and it is difficult to sampling isokinetically, change the filter.Monitor flow, temp., pressure, and notice changes.
68 Method 5 (cont.’d) Sampling recovery Clean and plug the nozzle, disassemble the probe (caution -- HOT!).Unplug the umbilical cord from the last & 1st impinger, plug impinger.Disassemble filter holder (caution -- HOT!)Rinse the nozzle & filter holder with acetone, but separate all acetone in different containers (record the volume of acetone used).
69 Method 5 (cont.’d) Analysis Weight silica gel in 4th impinger in the field (if the balance is available).Measure H2O volume left in the rest of impingers (1-3).Analysisequilibrate filter in weighting room at least 24 hrs. and weight the filter every 6-hr until weight differences are less than +/-0.5 mg (alternatively, heat at 105oC for 2-3 hrs. and cool down in desiccator before weighing)
70 Method 5 (cont.’d) Evapolate acetone before weight PM left in beaker. Add those weight together for PM mass.
78 เอกสารอ้างอิงCode of Federal Regulations, Method 5 - Determination of particulate emissions from stationary sources, Title 40 Part 60, App.A, 1995, US.Wight, G.D., Fundamentals of air sampling, 1994, Lewis Publishers, NY, US.
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