ADDENDA

B. Suggested Definitions of Performance Specifications:

Range The minimum and maximum measurement limits.

Output-Electrical signal which is proportional to the measurement; intended for connection to readout or data processing devices. Usually expressed as millivolts or milliamps full scale at a given impedence. Full Scale-The maximum measuring limit for a given range.

Minimum Detectable Sensitivity-The small

est amount of input concentration that can be detected as the concentration approaches zero.

Accuracy-The degree of agreement between

a measured value and the true value; usually expressed at percent of full scale.

Lag Time-The time interval from a step change in input concentration at the instrument inlet to the first corresponding change in the instrument output.

Time to 90 Percent Response-The time interval from a step change in the input concentration at the instrument inlet to a reading of 90 percent of the ultimate recorded concentration.

Rise Time (90 percent)-The interval between initial response time and time to 90 percent response after a step decrease in the inlet concentration.

Zero Drift-The change in instrument output over a stated time period, usually 24 hours, of unadjusted continuous operation, when the input concentration is zero; usually expressed as percent full scale.

Span Drift-The change in instrument output over a stated time period, usually 24 hours, of unadjusted continuous operation, when the input concentration is a stated upscale value; usually expressed as percent full scale.

Precision-The degree of agreement between repeated measurements of the same concentration. It is expressed as the average deviation of the single results from the

mean.

Operational Period-The period of time over which the instrument can be expected to operate unattended within specifications. Noise Spontaneous deviations from a mean output not caused by input concentration changes.

Interference-An undesired positive or negative output caused by a substance other than the one being measured. Interference Equivalent-The portion of indicated input concentration due to the presence of an interferent.

Operating Temperature Range-The range of ambient temperatures over which the instrument will meet all performance specifications.

APPENDIX F-REFERENCE METHOD FOR THE DETERMINATION OF NITROGEN DIOXIDE IN THE ATMOSPHERE (24-HOUR SAMPLING METHOD) 1. Principle and Applicability.

1.1 Nitrogen dioxide is collected by bubbling air through a sodium hydroxide solution to form a stable solution of sodium nitrite. The nitrite ion produced during sampling is determined colorimetrically by reacting the exposed absorbing reagent with phosphoric acid, sulfanilamide, and N-1naphthylethylenediamine dihydrochloride.

1.2 The method is applicable to collection of 24-hour samples in the field and subsequent analysis in the laboratory.

2. Range and Sensitivity.

2.1 The range of the analysis is 0.04 to 1.5 ug. NO,/ml. With 50 ml. absorbing reagent and a sampling rate of 200 ml./min. for 24 hours, the range of the method is 20-740 g./m. (0.01-0.4 p.p.m.) nitrogen dioxide.

2.2 A concentration of 0.04 ug. NO,/ml. will produce an absorbance of 0.02 using 1-cm. cells.

3. Interferences. 3.1 The interference of sulfur dioxide is eliminated by converting it to sulfuric acid with hydrogen peroxide before analysis. (1) 4. Precision, Accuracy, and Stability. 4.1 The relative standard deviations are 14.4 percent and 21.5 percent at nitrogen

dioxide concentrations of 140 ug./m.3 (0.072 p.p.m.) and 200 μg./m.3 (0.108 p.p.m.), respectively, based on an automated analysis of samples collected from a standard test atmosphere. Precision would probably be different when the analysis is performed manually.

4.2 No accuracy data are available. 4.3 Samples are stable for at least 6 weeks. 5. Apparatus.

5.1 Sampling. See Figure F1.

5.1.1 Absorber. Polypropylene tubes 164 x 32 mm., equipped with polypropylene twoport closures. Rubber stoppers cause high and varying blank values and should not be used. A gas dispersion tube with a fritted end of porosity B (70-100 μm. maximum pore diameter) is used.

5.1.1.1 Measurement of Maximum Pore Diameter of Frit. Carefully clean the frit with dichromate-concentrated sulfuric acid cleaning solution and rinse well with distilled water. Insert through one hole of a two-hole rubber stopper and install in a test tube containing sufficient distilled water to cover the fritted portion. Attach a vacuum source to the other hole of the rubber stopper and measure the vacuum required to draw the

Available from Bel-Art Products, Pequan

nock, N.J.

or

P Measured vacuum, mm. Hg. 5.1.2 Probe. Teflon, polypropylene, glass tube with a polypropylene or glass funnel at the end and a membrane filter to protect the frit. Replace filter after collecting five samples, or more often as indicated by visual observation of the loading.

5.1.3 Flow Control Device. Calibrated 27gauge hypodermic needle, three-eighths of an inch long to maintain a flow of approximately 0.2 liter/minute. The needle should be protected by a membrane filter. Change filter after collecting 10 samples.

5.1.4 Air Pump. Capable of maintaining a flow of 0.2 liter/minute through the absorber, and a vacuum of 0.7 atmosphere.

5.1.5 Calibration Equipment. Glass flowmeter for measuring airflows up to approximately 275 ml./min. within ±2 percent, stopwatch, and precision wet test meter (1 liter/revolution).

6.2.1 Sulfanilamide. Dissolve 20 g. sulfanilamide in 700 ml. distilled water. Add, with mixing, 50 ml. concentrated phosphoric acid (85 percent) and dilute to 1,000 ml. This solution is stable for a month if refrigerated.

6.2.2 NEDA Solution. Dissolve 0.5 g. N-1naphthylethylenediamine dihydrochloride in 500 ml. of distilled water. This solution is stable for a month if refrigerated and protected from light.

6.2.3 Hydrogen Peroxide. Dilute 0.2 ml. 30 percent hydrogen peroxide to 250 ml. with distilled water. This solution may be used for a month if protected from light.

6.2.4 Standard Nitrite Solution. Dissolve sufficient desiccated sodium nitrite (NaNO2, assay of 97 percent or greater) and dilute with distilled water to 1,000 ml. so that a solution containing 1,000 μg. NO2/ml. is obtained. The amount of NaNO2 to use is calculated as follows:

7.1 Sampling. Assemble the sampling train as shown in Figure F1. Add 50 ml. absorbing reagent to the absorber. Disconnect funnel, insert calibrated flowmeter, and measure flow before sampling. If flow rate before sampling is less than 85 percent of needle calibration, check for leak or change filters as necessary. Remove flowmeter and replace funnel. Sample for 24 hours from midnight to midnight and measure flow at end of sampling period.

7.2 Analysis. Replace any water lost by evaporation during sampling. Pipet 10 ml. of the collected sample into a test tube. Add 1.0 ml. hydrogen peroxide solution, 10.0 ml. sulfanilamide solution, and 1.4 ml. NEDA solution with thorough mixing after the addition of each reagent. Prepare a blank in the same manner using 10 ml. absorbing reagent. After a 10-minute color-development interval, measure the absorbance at 540 nm. against the blank. Read μg. NO;/ml. from standard curve (Section 8.2).

8. Calibration and Efficiencies. 8.1 Sampling.

8.1.1 Calibration of Flowmeter. Using a wet test meter and a stopwatch, determine the rates of air flow (ml./min.) through the flowmeter at several ball positions. Plot ball positions versus flow rates.

8.1.2 Calibration of Hypodermic Needle. Connect the calibrated flowmeter, the needle to be calibrated, and the source of vacuum in such a way that the direction of airflow through the needle is the same as in the sampling train. Read the position of the ball and determine flow rate in ml./min. from the calibration chart prepared in 8.1.1. Reject all needles not having flow rates of 190 to 210 ml./min. before sampling.

8.2 Calibration Curve. Dilute 5.0 ml. of the 1,000 g. NO2/ml. solution to 200 ml. with absorbing reagent. This solution contains 25 g. NO;/ml. Pipet 1, 2, 5, and 15 ml. of the 25 μg. NO2/ml. solution into 50-, 50-, 100-, and 250-ml, volumetric flasks and dilute to the mark with absorbing reagent. The solutions contain 0.50, 1.00, 1.25, and 1.50 ug. NO5/ml., respectively. Run standards as instructed in 7.2. Plot absorbance vs. #g. NO,/ml.

8.3 Efficiencies. An overall average effciency of 35 per cent was obtained from test atmospheres having nitrogen dioxide concentrations of 140 μg./m.3 and 200 μg./m. by automated analysis. (2)

V=Volume of air sampled, m.*

ml./min.

9.2

g. NO,/m.=.

(ug. NO,/ml.) X50

V=Volume of air sampled, m."

0.35 Efficiency.

9.2.1 If desired, concentration of nitrogen dioxide may be calculated as p.p.m. NO,. p.p.m. (ug. NO,/m.3) X 5.32 × 10-4 10. References.

(1) Jacobs, M. B., and Hochheiser, S., "Continuous Sampling and Ultramicrodetermination of Nitrogen Dioxide in Air", Anal. Chem., 30 426 (1958). (2) Purdue, L. J., Dudley, J. E., Clements, J. B., and Thompson, R. J., "Studies in Air Sampling for Nitrogen Dioxide," I. A reinvestigation of the JacobsHochheiser Reagent. In Preparation.

MEMBRANE FILTER

51.30 Request for 2-year extension. 51.31 Request for 18-month extension. 51.32 Request for 1-year postponement. Appendix A-Air Quality Estimation. Appendix B-Examples of Emission Limitations Attainable with Reasonably Available Technology.

Appendix C-Major Pollutant Sources. Appendix D-Emissions Inventory Summary (Examples Regions).

Appendix E-Point Source Data.
Appendix F-Area Source Data.
Appendix G-Emmissions Inventory Sum-
mary (Other Regions).

Appendix H-Air Quality Data Summary.
Appendix I-Projected Motor Vehicle Emis-

sions.

Appendix J-Required Hydrocarbon Emission Control as & Function of Photochemical Oxidant Concentrations.

Appendix K-Control Agency Functions. Appendix L-Example Regulations for Prevention of Air Pollution Emergency Episodes.

AUTHORITY: The provisions of this Part 51 issued under section 301(a) of the Clean Air Act (42 U.S.C. 1857(a), as amended by section 15(c) (2) of Public Law 91-604, 84 Stat. 1713.

SOURCE: The provisions of this Part 51 appear at 36 F.R. 22398, Nov. 25, 1971, unless otherwise noted.

Subpart A-General Provisions § 51.1

Definitions.

As used in this part, all terms not defined herein shall have the meaning given them in the Act:

(a) "Act" means the Clean Air Act (42 U.S.C. 1857-18571, as amended by Public Law 91-604, 84 Stat. 1676).

the

(b) "Administrator" means Administrator of the Environmental Protection Agency (EPA) or his authorized representative.

(c) "Primary standard' means a national primary ambient air quality standard promulgated pursuant to section 109 of the Act.

(d) "Secondary standard' means a national secondary ambient air quality standard promulgated pursuant to section 109 of the Act.

(e) "National standard” means either a primary or a secondary standard.

(f) "Owner or operator" means any person who owns, leases, operates, controls, or supervises a facility, building,

structure, or installation which directly or indirectly results or may result in emissions of any air pollutant for which a national standard is in effect.

(g) "Local agency" means any local government agency, other than the State agency, which is charged with the responsibility for carrying out a portion of a plan.

(h) "Regional Office" means one of the ten (10) EPA Regional Offices.

(i) "State agency" means the air pollution control agency primarily responsible for development and implementation of a plan under the Act.

(j) "Local agency" means any air pollution control agency other than a State agency, which is charged with responsibility for carrying out a portion of a plan.

(k) "Point source" means:

(1) Any stationary source causing emissions in excess of 100 tons (90.7 metric tons) per year of any pollutant for which there is a national standard in a region containing an area whose 1970 "urban place" population, as defined by the Bureau of Census, was equal to or greater than 1 million or

(2) Any stationary source causing emissions in excess of 25 tons (22.7 metric tons) per year of any pollutant for which there is a national standard in a region containing an area whose 1970 "urban place" population, as defined by the U.S. Bureau of the Census, was less than 1 million and

(3) Without regard to amount of emissions, stationary sources such as those listed in Appendix C to this part. (1) "Area source" means any small residential, governmental, institutional, commercial, or industrial fuel combustion operations: onsite solid waste disposal facility; motor vehicles, aircraft, vessels, or other transportation facilities; or other miscellaneous sources such as those listed in Appendix D to this part, as identified through inventory techniques similar to those described in: “A Rapid Survey Technique for Estimating Community Air Pollution Emissions," Public Health Service Publication No. 999-AP-29, October 1966.

(m) "Region" means (1) an air quality control region designated by the Secretary of Health, Education, and Welfare or the Administrator, (2) any area designated by a State agency as an air quality control region and approved by the Administrator, or (3) any area of a State not designated as an air quality