N.J. Admin. Code § 7:27B-3.8

Current through Register Vol. 56, No. 19, October 7, 2024

Section 7:27B-3.8 - Procedures for the direct measurement of volatile organic compounds using a gas chromatograph (GC) with a flame ionization detector (FID) or other suitable detector

(a) The method in this section is applicable for the determination of the concentrations and the mass emission rates of any known VOC in unknown proportions in systems with constant emissions and flow rates. For the same circumstances as described above, the procedure specified in 7:27B-3.9 may be used in place of this method. Any other alternative test method shall be submitted to the Department for review pursuant to 7:27B-3.2(c), (d) and (e).

(b) This method is based upon the following principles:

1. Gas chromatography, whereby VOC are separated by passing an inert gas stream containing a known volume of the sample gas or a standard gas through a column containing a suitable stationary phase and/or a solid support; and

2. Ionization produced when each VOC in the gas sample as eluted from the gas chromatograph is combusted in a hydrogen flame. The ions and electrons formed in the flame enter an electrode gap, decrease the gas resistance, and thus permit a current flow in an external circuit. The resulting current is proportional to the instantaneous concentration of the VOC. Any alternative detector shall be submitted to the Department for review pursuant to 7:27B-3.2(c), (d) and (e).

(c) The following is a summary of this method:

1. The GC-FID is calibrated with standard gas mixtures containing each VOC being measured to establish the calibration curves and retention times. A representative sample is drawn into the gas sampling loop under conditions which prevent any condensation of the sample gas and which remove particulate matter. The sample is injected into the GC, the responses and retention times of the individual VOC are recorded on a strip chart recorder, and the peak areas of each VOC are measured. The peaks are identified from the established retention times. The concentration of each VOC is determined by referring to the calibration curve. The total gas flow rate, moisture content, and the average molecular weight of the gas are determined during the sampling period, and the mass emission rate of the VOC is calculated and reported as pounds per hour.

2. For the purposes of this procedure, three separate test runs will be conducted, each of which shall extend for one hour or a batch cycle whichever is longer. Any alternative test period shall be submitted to the Department for review pursuant to 7:27B-3.2(c), (d) and (e).

3. In situations where safety considerations, location, or number of sample points prohibit direct analysis at the VOC source, the samples are collected in accordance with the method prescribed in 7:27B-3.9 and transported to the GC-FID for analysis.

(d) The following is a list of equipment used in this method:

1. Probe;

2. Sample line;

3. Temperature sensor;

4. Pump;

5. Gas sampling valve;

6. Needle valve;

7. Gas chromatograph-flame ionization detector (GC-FID);

8. Recorder/Integrator;

9. Gas cylinder supplies as follows:

i. Laboratory standard calibration gases;

ii. Pure components standard;

iii. Fuel gas;

iv. Combustion gas; and

v. Carrier gas.

10. Velocity meter;

11. Condensor; and

12. Dilution system (if necessary): a system as described in 7:27B-3.9.(e)4, capable of producing dilution ratios which will prevent any condensation of the sample gas and capable of bringing the sample concentration within the linear range of the GC detector.

(e) The procedure for this section shall be as follows:

1. A presampling survey of the source operation(s) shall be conducted to establish certain basic information including but not limited to: sampling location; stack temperature and pressure; stack gas moisture content; approximate particulate concentration; composition of the gases; and the identification and approximate concentrations of the VOC to be analyzed. It may be necessary to take samples for analysis to acquire any information that is not readily available.

2. The instruction shall be calibrated as follows:

i. The instruction shall be operated according to the manufacturer's instructions;

ii. The operating parameters of the instruction such as column selections, temperatures, carrier gas flow rate, and chart speed shall be established for the VOC to be measured and verified in the laboratory prior to actual sampling. The conditions selected should produce baseline separation of the individual VOC peaks, if possible, but in no case should the height of the valley between the two peaks measured from the baseline to the lowest point in the valley be greater than 30 percent of the height of the shorter of the two peaks. More than one set of conditions may be necessary for complete resolution;

iii. The instrument operating conditions shall be recorded on the chart and maintained throughout the calibration and sample gas analyses. The operating conditions to be recorded are sample loop temperature, column temperature, carrier gas flow rate, and chart speed. Attenuator setting shall be adjusted as required and recorded on the chart to indicate the time and amount of adjustment;

iv. Purge the sample loop with one of the calibration gas mixtures and record the concentration;

v. Activate the sampling valve to inject the sample and mark the injection point on the chart;

vi. Measure the distance on the chart from the injection point to the time at which the peak maximum occurs for the calibration mixture. This distance divided by the chart speed will provide the retention time for each compound;

vii. Calculate the sample peak areas by multiplying the height times the width at half height and adjust each peak area by the attenuator setting as required. An integrator may be used to calculate peak areas;

viii. Repeat steps iv through vii for each calibration gas until two consecutive analyses agree within five percent. The corresponding peak areas for each VOC shall then be averaged;

ix. Plot the areas of each peak versus the concentration on suitable graph paper. If any point should deviate from a straight line by more than five percent, the calibration shall be repeated. If a straight line is not obtained, less concentrated standards or a smaller sample must be used to bring the response within the linear range of the detector; and

x. Draw a straight line through the points to establish a calibration curve for each VOC. Calculate the unknown VOC concentrations from their peak areas by reading from the appropriate calibration curve or by multiplying the peak area by the slope of the calibration curve. Extrapolation beyond the calibrated range is not acceptable.

xi. The instrument calibration shall be checked just prior to each test. The calibration gas shall be introduced through the sampling system in a manner similar to the introduction of the source gas.

3. The sampling and analysis shall be conducted as follows:

i. Assemble and connect any sampling probe, sample line, filter and heating or dilution system to the GC-FID. All connections shall be tight.

ii. Turn on the GC and source gas sampling systems and adjust conditions to prevent any condensation of the sample gas;

iii. If a dilution system is used, run three field standards through the dilution system and the instrument and record each response. The response shall not deviate from linearity by more than five percent;

iv. The probe shall be positioned at least two feet into the stack or at the centroid of the stack. The sample port location shall be in accordance with N.J.A.C. 7:27B-1, AIR TEST METHOD 1 (7:27B-3.18, Reference 1);

v. After thoroughly purging the gas sampling loop with source gas, analyze a sample of the source gas maintaining the same instrument operating conditions used during the calibration procedures. Calculate the concentrations of the components by referring to the calibration curve; and

vi. Repeat the analysis at uniform intervals as many times as practical during the test run. No less than three sample analyses per test run shall be acceptable;

vii. For the purposes of this procedure three separate and valid test runs will be conducted, each of which shall extend for one hour or a batch cycle whichever is longer. Any alternative test period shall be submitted to the Department for review pursuant to 7:27B-3.2(c), (d) and (e).

viii. During the test period, determine the stack gas velocity, temperature, moisture content, average gas molecular weight, and volumetric flow rates in accordance with the methods prescribed in N.J.A.C. 7:27B-1, AIR TEST METHOD 1 (7:27B-3.18, Reference 1), or other flow determining method submitted to the Department for review pursuant to 7:27B-3.2(c), (d) and (e). See Appendix A for the required reporting form. (Any alternative reporting forms shall be submitted to the Department for review pursuant to 7:27B-3.2(c) and (e).)

ix. At the conclusion of each test run introduce the calibration gas in a manner similar to the introduction of the source gas and determine the response. The net response must agree to within +/- five percent of the pretest response for the test to be valid.

(f) The calculations shall be performed as follows:

1. Establish the molecular weight of each VOC.

2. Calculate the total gas flow rate from the source operation(s) in SCFM (70 [degree]F and 1 atm) including the contribution of the VOC and any moisture present.

3. Record the individual concentrations (C ppm) and determine the average concentration (C) of each VOC in ppm (avg. C ppm) for each test run from the calibration curves.

4. Calculate the emission rate in lbs/hr of each VOC as follows:

Avg. C ppm(VOC)
lbs VOC	=	x MW(VOC) x SCFM
_______________________________________
hr	387 x 10 [LESS THAN] 6 [GREATER THAN]

Where:

Avg. C ppm(VOC)=average parts per million of VOC over the test period.

MW (VOC)=molecular weight of VOC (pounds per pound-mol).

SCFM=cubic feet per minute at 70 [degree]F and 1 atm emitted from the source operation.

387=molar volume at standard conditions in cubic feet per pound-mol.

NOTE: This formula is based upon the assumption that both the standards and the sample have been passed through the same sampling system and diluted by the same amount.

5. Calculate the total emission rate in lbs/hr of the VOC by totaling the individual VOC calculated in (f)4 above.

(g) The test report shall include the following information submitted on the required reporting form in Appendix C (any alternative reporting form shall be submitted to the Department for review pursuant to 7:27-3.2(c) and (e)) :

1. A dimensioned sketch of the sampling location;

2. All data used to determine the volume flow rates;

3. The composition of the gas and its average molecular weight;

4. A sketch and/or description of the sampling system used;

5. The identity, concentration, and means of verification for each standard used;

6. A description of the analysis instrument and the conditions of operation;

7. Copies of the chromatograms for each standard and each test run identified as to time taken and pertinent instrument and dilution conditions;

8. Sufficient details of the calculations to allow the results to be reproduced independently;

9. The emission rate measured in lbs/hr of each VOC for each test;

10. Operating conditions of the source operations; and

11. An explanation for any unusual procedures or results.

N.J. Admin. Code § 7:27B-3.8

Amended by R.1992 d.102, effective 3/2/1992 (operative March 28, 1992).
See: 23 New Jersey Register 1858(b), 24 New Jersey Register 792(a).
"VOS" replaced by "VOC".