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Figure 7-1. Sampling train, flask valve, and Ilask. 2.2.3. Glass wash bottle.

3.3 Analysis. 2.3 Analysis.

3.3.1 Fuming sulfuric acid-15 to 18% by 2.3.1 Steam bath.

weight free sulfur trioxide. 2.3.2 Beakers or casseroles—250 ml., one 3.3.2 Phenol-White solid reagent grade. for each sample and standard (blank).

3.3.3 Sulfuric acid-Concentrated reagent 2.3.3 Volumetric pipettes—1, 2, and 10 ml. grade.

2.3.4 Transfer pipette-10 ml, with 0.1 ml. 3.3.4 Standard solution-Dissolve 0.5495 g. divisions.

potassium nitrate (KNO3) in distilled water 2.3.5 Volumetric flask—100 ml., one for and dilute to 1 liter. For the working stand. each sample, and 1,000 ml, for the standard ard solution, dilute 10 ml. of the resulting (blank).

solution to 100 ml. with distilled water. One 2.3.6 Spectrophotometer-To measure ab ml. of the working standard solution is sorbance at 420 nm.

equivalent to 25 mg. nitrogen dioxide. 2.3.7 Graduated cylinder-100 ml. with 3.3.5 Water-Deionized, distilled. 1.0 ml. divisions.

3.3.6 Phenoldisulfonic acid solution2.3.8 Analytical balance-To measure to Dissolve 25 g. of pure white phenol in 150 ml. 0.1 mg.

concentrated sulfuric acid on & steam bath. 3. Reagents.

Cool, add 75 ml. fuming sulfuric acid, and 3.1 Sampling.

heat at 100° C. for 2 hours. Store in a dark, 3.1.1 Absorbing solution-Add 2.8 ml. of stoppered bottle. concentrated H,So, to 1 liter of distilled 4. Procedure. water. Mix well and add 6 ml. of 3 percent 4.1 Sampling. hydrogen peroxide. Prepare a fresh solution 4.1.1 Pipette 25 ml. of absorbing solution weekly and do not expose to extreme heat or Into a sample flask. Insert the flask valve direct sunlight.

stopper into the flask with the valve in the 3.2 Sample recovery.

"purge" position. Assemble the sampling 3.2.1 Sodium hydroxide (1N)-Dissolve train as shown in Figure 7-1 and place the 40 g. NaOH in distilled water and dilute to 1 probe at the sampling point. Turn the flask liter.

valve and the pump valve to their "evacuate" 3.2.2 Red litmus paper.

positions. Evacuate the flask to at least 3 3.2.3 Water-Deionized, distilled.

inches Hg absolute pressure. Turn the pump

valve to its "vent" position and turn off the pump. Check the manometer for any fuctuation in the mercury level. If there is a visible change over the span of one minute, check for leaks. Record the initial volume, temperature, and barometric pressure. Turn the flask valve to its "purge" position, and then do the same with the pump valve. Purge the probe and the vacuum tube using the squeeze bulb. I condensation occurs in the probe and flask valve area, heat the probe and purge until the condensation disappears.

Then turn the pump valve to its “vent" posttion. Turn the flask valve to its "sample" position and allow sample to enter the flask for about 15 seconds. After collecting the sample, turn the flask valve to its "purge" position and disconnect the flask from the sampling train. Shake the flask for 5 minutes.

4.2 Sample recovery.

4.2.1 Let the flask set for a minimum of 16 hours and then shake the contents for 2 minutes. Connect the flask to & mercury filled U-tube manometer, open the valve from the flask to the manometer, and record the flask pressure and temperature along with the barometric pressure. Transfer the flask contents to a container for shipment or to a 250 ml, beaker for analysis. Rinse the flask with two portions of distilled water (approximately 10 ml.) and add rinse water to the sample. For a blank use 25 ml. of absorbing solution and the same volume of distilled water as used in rinsing the flask. Prior to shipping or analysis, add sodium hydroxide (1N) dropwise into both the sample and the blank until alkaline to litmus paper (about 25 to 35 drops in each).

4.3 Analysis.

4.3.1 If the sample has been shipped in & container, transfer the contents to & 250 ml. beaker using a small amount of distilled

water. Evaporate the solution to dryness on a steam bath and then cool. Add 2 ml. phenoldisulfonic acid solution to the dried residue and triturate thoroughly with a glass rod. Make sure the solution contacts all the residue. Add 1 ml. distilled water and four drops of concentrated sulfuric acid. Heat the solution on & steam bath for 3 minutes with occasional stirring. Cool, add 20 ml. distilled water, mix well by stirring, and add concentrated ammonium hydroxide dropwise with constant stirring until alkaline to litmus paper. Transfer the solution to a 100 ml. volumetric flask and wash the beaker three times with 4 to 5 ml. portions of distilled water. Dilute to the mark and mix thoroughly. If the sample contains solids, transfer a portion of the solution to a clean, dry centrifuge tube, and centrifuge, or filter & portion of the solution. Measure the absorbance of each sample at 420 nm. using the blank solution as a zero, Dilute the sample and the blank with a suitable amount of distilled water if absorbance falls outside the range of calibration.

5. Calibration.

5.1 Flask volume. Assemble the flask and flask valve and fill with water to the stopcock. Measure the volume of water to +10 ml. Number and record the volume on the flask.

5.2 Spectrophotometer. Add 0.0 to 16.0 ml. of standard solution to a series of beakers. To each beaker add 25 ml. of absorbing solution and add sodium hydroxide (1N) dropwise until alkaline to litmus paper (about 25 to 35 drops). Follow the analysis procedure of section 4.3 to collect enough data to draw a callbration curve of concentration in ug. NO. per sample versus absorbance.

6. Calculations.
6.1 Sample volume.

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where:

P,-Final absolute pressure of flask,

inches Hg. V..-Sample volume at standard condi

P,= Initial absolute pressure of flask, tions (dry basis), ml.

inches Hg. T... - Absolute temperature at standard T,=Final absolute temperature of flask, conditions, 530° R.

°R.

T.-Initial absolute temperature of flask, Pre-Pressure at standard conditions, 29.92 inches Hg.

6.2 Sample concentration. Read ug. NO, V,- Volume of flask and valve, ml.

for each sample from the plot of ug. NO, V.-Volume of absorbing solution, 25 ml. versus absorbance.

1 lb.

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ug.
I n ug./ml.) (V.)

equation 7-2 where:

7. References. C=Concentration of NO, as NO, (dry Standard Methods of Chemical Analysis. basis), Ib./s.c.f.

6th ed. New York, D. Van Nostrand Co., Inc., m-Mass of No, in gas sample, ug.

1962, vol. 1, p. 329-330. V.-Sample volume at standard condi- Standard Method of Test for Oxides of tions (dry basis), ml.

Nitrogen in Gaseous Combustion Products 97-025—73- 32

489

(Phenoldisulfonic Acid Procedure), In: 1968 Book of ASTM Standards, Part 23, Philadelphia, Pa. 1968, ASTM Designation D-1608-60, p. 725–729.

Jacob, M. B., The Chemical Analysis of Air Poliutants, New York, N.Y., Interscience Publishers, Inc., 1960, vol. 10, p. 351-358. METHOD 8-DETERMINATION OF SULFURIC ACID

MIST AND SULFUR DIOXIDE EMISSIONS FROM STATIONARY SOURCES 1. Principle and applicability.

1.1 Principle. A gas sample is extracted from a sampling point in the stack and the acid mist including sulfur trioxide is separated from sulfur dioxide. Both fractions are measured separately by the barium-thorin titration method.

1.2 Applicability. This method is applicable to determination of sulfuric acid mist (including sulfur trioxide) and sulfur dioxide from stationary sources only when specified by the test procedures for determining compliance with the New Source Performance Standards.

2. Apparatus.

2.1 Sampling. See Figure 8-1. Many of the design specifications of this sampling train are described in APTD-0581.

2.1.1 Nozzle Stainless steel (316) with sharp, tapered leading edge.

2.1.2 Probe Pyrex1 glass with a heating system to prevent visible condensation during sampling.

2.1.3 Pitot tube-Type S, or equivalent, attached to probe to monitor stack gas velocity.

2.1.4 Filter holder-Pyrex glass.

2.1.5 Impingers-Four as shown in Figure 8-1. The first and third are of the GreenburgSmith design with standard tip. The second and fourth are of the Greenburg-Smith design, modified by replacing the standard tip with a 12-inch ID glass tube extending to one-half inch from the bottom of the impinger flask. Similar collection systems, which have been approved by the Administrator, may be used.

2.1.6 Metering system-Vacuum gauge, leak-free pump, thermometers capable of measuring temperature to within 5° F., dry gas meter with 2% accuracy, and related equipment, or equivalent, as required to maintain an isokinetic sampling rate and to determine sample volume.

2.1.7 Barometer—To measure atmospheric pressure to +0.1 inch Hg.

· Trade name.

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2.2 Sample recovery.
2.2.1 Wash bottles-Two.

2.2.2 Graduated cylinders—250 ml., 500 ml.

2.2.3 Glass sample storage containers.
2.2.4 Graduated cylinder-250 ml.
2.3 Analysis.
2.3.1 Pipette-25 ml., 100 ml.
2.3.2 Burette-50 ml.
2.3.3 Erlenmeyer flask—250 ml.
2.3.4 Graduated cylinder-100 ml.

2.3.5 Trip balance 300 g. capacity, to measure to +0.05 g.

2.3.6 Dropping bottle to add indicator solution.

3. Reagents.
3.1 Sampling.

3.1.1 Futers-Glass fiber, MSA type 1106 BH, or equivalent, of a suitable size to it in the filter holder.

3.1.2 Silica gel-Indicating type, 6-16 mesh, dried at 175° C. (350° F.) for 2 hours.

3.1.3 Water-Deionized, distilled.

3.1.4 Isopropanol, 80%-Mix 800 ml. of Isopropanol with 200 ml. of deionized, distilled water.

3.1.5 Hydrogen peroxide, 3%-Dilute 100 ml. of 30% hydrogen peroxide to 1 liter with deionized, distilled water.

3.1.6 Crushed ice.
3.2 Sample recovery.
3.2.1 Water-Deionized, distilled.
3.2.2 Isopropanol, 80%.
3.3 Analysis.
3.3.1 Water-Delonized, distilled.
3.3.2 Isopropanol.

3.3.3 Thorin indicator-1-(0-arsonophenylazo)-2-naphthol-3, 6-disulfonic acid, disodium salt (or equivalent). Dissolve 0.20 g. in 100 ml, distilled water.

3.3.4 Barium perchlorate (0.01N)-Dissolve 1.95 g. of barium perchlorate (Ba (CO.), 3 H,O) in 200 ml. distilled water and dilute to 1 liter with isopropanol. Standardize with sulfuric acid.

3.3.5 Sulfuric acid standard (0.01N) Purchase or standardize to + 0.0002 N against 0.01 N NaOH which has previously been standardized against primary standard potassium acid phthalate.

4. Procedure.
4.1 Sampling.

4.1.1 After selecting the sampling site and the minimum number of sampling points, determine the stack pressure, temperature, moisture, and range of velocity head.

4.1.2 Preparation of collection train. Place 100 ml. of 80% isopropanol in the first impinger, 100 ml. of 3% hydrogen peroxide in both the second and third impingers, and about 200 g. of silica gel in the fourth impinger. Retain a portion of the reagents for use as blank solutions. Assemble the train without the probe as shown in Figure 8-1 with the filter between the first and second impingers. Leak check the sampling train at the sampling site by plugging the inlet to the first impinger and pulling a 15-inch Hg vacuum. A leakage rate not in excess of 0.02 c.i.m. at a vacuum of 15 inches Hg is acceptable. Attach the probe and turn on the probe heating system. Adjust the probe heater setting during sampling to prevent any visible condensation, Place crushed ice around the impingers. Add more ice during the run to keep the temperature of the gases leaving the last impinger at 70° F. or less.

4.1.3 Train operation. For each run, record the data required on the example sheet shown in Figure 8-2. Take readings at each sampling point at least every 5 minutes and when significant changes in stack conditions necessitate additional adjustments in flow rate. To begin sampling, position the nozzle at the first traverse point with the tip pointing directly into the gas stream. Start the pump and immediately adjust the flow to isokinetic conditions. Maintain isokinetic sampling throughout the sampling period. Nomographs are available which aid in the rapid adjustment of the sampling rate without other computations. APTD-0576 details the procedure for using these nomographs. At the conclusion of each run, turn off the pump and record the final readings. Remove the probe from the stack and disconnect It from the train, Drain the ice bath and purge the remaining part of the train by drawing clean ambient air through the system for 15 minutes.

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4.2 Sample recovery.

4.2.1 Transfer the isopropanol from the first impinger to a 250 ml. graduated cylinder. Rinse the probe, first impinger, and all connecting glassware before the filter with 80% Isopropanol. Add the rinse solution to the cylinder. Dilute to 250 ml, with 80% Isopropanol. Add the filter to the solution, mix, and transfer to a suitable storage container. Transfer the solution from the second and third impingers to a 500 ml. graduated cylInder. Rinse all glassware between the filter and silica gel impinger with deionized, distilled water and add this rinse water to the cylinder. Dilute to a volume of 500 ml. with deionized, distilled water. Transfer the solution to a suitable storage container.

4.3 Analysis.

4.3.1 Shake the container holding 1sopropanol and the filter. If the filter breaks up, allow the fragments to settle for a few minutes before removing a sample. Pipette & 100 ml. aliquot of sample into a 250 ml. Erlenmeyer flask and add 2 to 4 drops of thorin indicator. Titrate the sample with

barium perchlorate to a pink end point. Make sure to record volumes. Repeat the titration with a second aliquot of sample. Shake the container holding the contents of the second and third impingers. Pipette a 25 ml. aliquot of sample into a 250 ml, Erlenmeyer flask. Add 100 ml, of isopropanol and 2 to 4 drops of thorin indicator. Titrate the sample with barium perchlorate to a pink end point. Repeat the titration with a second aliquot of sample. Titrate the blanks in the same manner as the samples.

5. Calibration.

5.1 Use standard methods and equipment which have been approved by the Administrator to calibrate the orifice meter, pitot tube, dry gas meter, and probe heater.

5.2 Standardize the barium perchlorate with 25 ml. of standard sulfuric acid containing 100 ml. of isopropanol.

6. Calculations.

6.1 Dry gas volume. Correct the sample volume measured by the dry gas meter to standard conditions (70° F., 29.92 inches Hg) by using Equation 8-1.

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