Stack Emission Testing — EPA & DNER Compliance in Puerto Rico

Performance tests (stack tests or source tests) are point-in-time evaluations that quantify the actual emissions of a stationary source under typical or maximum operating conditions. C&S designs, coordinates, and executes these tests in strict accordance with EPA reference methods in 40 CFR Part 60, Appendix A, and 40 CFR Part 63, Appendix A, and in compliance with DNER’s Regulation for the Control of Atmospheric Pollution (RCAP). 

Our full-service process includes: 

• Pre-test protocol development and submission to DNER (Rule 106(C) of RCAP) at least 30 days before the test date. 

• Sampling program design: traverse point layout (EPA Method 1), port location verification, and equipment selection based on stack geometry and source type. 

• Synchronization of the C&S data acquisition system (DAS) clock with the facility operations clock to ensure data integrity. 

• Mobilization of calibrated field equipment to the site, including isokinetic trains, pitot tubes, S-type probes, impingers, FTIR analyzers, O2/CO2 CEMs, and digital thermometers. 

• Execution of three (3) one-hour test runs per source at maximum or representative operating load (within 10% of maximum peak load). 

• Post-test sample recovery, chain of custody documentation, and laboratory coordination for gravimetric and wet chemistry analysis. 

• Final test report preparation and submission to DNER/EQB within 60 days of the last day of testing. 

Source types we service: 

• Stationary internal combustion engines (spark ignition: natural gas, propane, gasoline; compression ignition: diesel) 

• Gas turbines and steam turbines (including Solar Turbines Centaur series and GE Jenbacher engines) 

• Industrial, hospital, and hotel boilers 

• Combined Heat and Power (CHP) cogeneration systems 

• Emergency and standby generators 

• Pathologic waste and industrial incinerators 

• Process equipment in the pharmaceutical, food & beverage, and manufacturing industries 

Subpart JJJJ of the NSPS (40 CFR Part 60) regulates stationary spark ignition (SI) engines fueled by natural gas, propane, or gasoline, rated at 25 HP or greater. This regulation applies broadly to cogeneration engines, emergency generators, and pumping engines at hospitals, pharmaceutical plants, hotels, and industrial facilities throughout Puerto Rico. 

C&S has performed NSPS JJJJ testing on Jenbacher J420 CHP engines (1,966 bhp, LNG-fueled) at industrial facilities, including simultaneous upstream and downstream sampling to verify Selective Catalytic Reduction/Oxidation System (SCROS) efficiency. 

Services include: 

• Initial Performance Test for NOx, CO, VOC (as propane equivalent), and Formaldehyde per § 60.4244 and Table 2 of Subpart JJJJ. 

• VOC speciation using FTIR: Propane, Benzene, Butane, Hexane, Toluene, and Pentane converted to carbon equivalent and reported as propane equivalent in ppmvd at 15% O2. 

• Formaldehyde determination and reporting as a separate pollutant (excluded from total VOC per Subpart JJJJ). 

• Emission control device (SCROS/oxidation catalyst) efficiency testing: simultaneous sampling at inlet and outlet of the control device to calculate percent removal efficiency for NOx, CO, VOC, and formaldehyde. 

• Exhaust flow rate determination using EPA Method 19 (F-factor method) — applicable when CHP heat recovery units or ductwork preclude conventional Method 2 velocity traverses. 

• Compliance determination against Table 1 of Subpart JJJJ limits: NOx ≤ 82 ppmvd, CO ≤ 270 ppmvd, VOC ≤ 60 ppmvd at 15% O2 (for non-emergency engines ≥ 100 HP). 

• Preparation of Initial Notification and Initial Performance Test Report for DNER and EPA Region 2. 

Subpart KKKK (40 CFR Part 60) regulates stationary combustion turbines with output capacity exceeding 10 MW. In Puerto Rico, this regulation applies to cogeneration turbines, industrial gas turbines, and backup turbines in the hospital and pharmaceutical sectors. C&S has performed NSPS KKKK testing on the Solar Turbines Centaur 40-4700 CHP Turbine (42.79 MMBtu/hr) at Destilería Serrallés, Inc. in Mercedita, PR. 

Services include: 

• Performance testing for NOx (ppmvd at 15% O2) and SO2 (lb/MMBtu heat input) per § 60.4320(a) and § 60.4330(b). 

• Multi-load emission factor testing: three (3) load conditions (maximum, intermediate, and low) to develop emission factors for NOx, SO2, CO, VOC, and Formaldehyde per permit requirements. 

• Moisture determination using EPA Method 320 (FTIR-based, self-validating) as an approved alternative to Method 4. 

• Calculation of NOx emission rates in lb NOx/MWh for comparison against Subpart KKKK limits. 

• Visible Emissions (opacity) observation per EPA Method 9, concurrent with performance testing. 

• Coordination of the Initial Performance Test Report and Subsequent Performance Tests per § 60.4375 and § 60.4380. 

• Preparation of complete final report including: process description, sampling locations, QA/QC procedures, raw field data sheets, calibration records, and calculation documentation. 

C&S operates a MKS Model 2030 Fourier Transform Infrared Spectroscopy (FTIR) multi-gas analyzer — one of the most advanced instruments available for stationary source emission testing. The FTIR allows simultaneous measurement of multiple pollutants in a single sampling run, reducing test time and improving data quality consistency. 

How FTIR works: Infrared absorption spectroscopy is performed by directing an infrared beam through the gas sample to a detector. Most molecules absorb infrared radiation in a characteristic and reproducible pattern. Within defined constraints, there is a linear relationship between infrared absorption and compound concentration, allowing the system to identify and quantify multiple compounds simultaneously from their unique spectral signatures. 

The MKS 2030 simultaneously measures: 

• NOx (as NO + NO2) — per EPA Methods 7E and 320 

• CO — per EPA Methods 10 and 320 

• SO2 — per EPA Methods 6C and 320 

• VOC — per EPA Methods 25A and 320 (individual compounds: Propane, Benzene, Butane, Hexane, Toluene, Pentane, Methane) 

• Formaldehyde (HCHO) — per EPA Method 320 (reported separately from total VOC) 

• Moisture (%H2O) — per EPA Method 320, as an approved alternative to Method 4 

The FTIR system includes: 

• Stainless steel extraction probe with heated, 3/8-inch Teflon® sample line maintained at 240–260°F to prevent condensation. 

• Built-in spike recovery validation procedure (12 spike samples) to confirm analyzer response before each test. 

• Data acquisition system (DAS) with one-minute average data logging throughout each test run. 

• Pre- and post-test calibration using NIST-traceable EPA Protocol 1 certified reference gas mixtures. 

Particulate matter (PM) sampling is performed isokinetically — extracting the gas sample at the same velocity as the stack gas flow — to ensure the sample is representative of actual in-stack conditions. C&S has performed PM testing on pathologic waste incinerators (B&L Cremation Systems, 150 lb/hr capacity) and other stationary sources throughout Puerto Rico. 

The EPA Method 5 sampling train consists of: 

• Glass-lined, heat-traced probe with stainless steel button-hook nozzle and attached thermocouple and pitot tube. 

• Probe and filter maintained at 248°F ± 25°F to prevent condensation of semi-volatile compounds on the filter. 

• Pre-weighed glass fiber filter in a heated filter chamber. 

• Four-impinger train: (1) modified Greenburg-Smith with 100 mL distilled water, (2) Greenburg-Smith with 100 mL distilled water, (3) empty modified Greenburg-Smith, (4) modified Greenburg-Smith with silica gel for moisture capture. 

• Control console with sample pump, dry gas meter, inclined manometer, and calibrated orifice meter. 

Sample recovery and analysis: 

• Nozzle and probe rinsed and brushed three times with reagent-grade acetone. Rinsate collected in Nalgene or glass containers. 

• Filter removed and sealed in a Petri dish with Teflon tape. Desiccated for a minimum of 24 hours before gravimetric weighing to constant weight. 

• Probe wash evaporated in an air-filtered lab hood, then desiccated and weighed to constant weight. 

• Acetone field blank collected and subtracted from probe wash results to correct for reagent impurities. 

• Isokinetic sampling maintained within ±10% of 100% throughout each run, per EPA Method 5 requirements. 

VOC emissions are ozone precursors regulated under the Clean Air Act at both federal and state level. C&S measures VOC concentrations using both the FTIR multi-gas analyzer (Method 320) and a portable flame ionization detector (FID) analyzer (Method 25A), depending on the regulatory requirement and source type. 

VOC speciation approach (per NSPS JJJJ requirements): 

• Individual compounds measured and reported: Propane (C3H8), Benzene (C6H6), Butane (C4H10), Hexane (C6H14), Toluene (C7H8), and Pentane (C5H12). 

• Pre-test screening of the exhaust performed to identify any additional VOC compounds present. If detected, additional compounds are added to the total. 

• All compounds converted to a carbon equivalent and totaled, then converted to a propane equivalent for final reporting. 

• Results reported in ppmvd and ppmvd corrected to 15% O2. 

• Methane and Formaldehyde are excluded from the total VOC value and reported separately. 

Formaldehyde is a toxic air pollutant regulated under multiple NSPS and NESHAP standards. It is a required measurement for CHP cogeneration systems and certain industrial engines under NSPS Subpart JJJJ and specific EQB/DNER permit conditions. 

C&S measures formaldehyde using the MKS Model 2030 FTIR analyzer under EPA Method 320. Key features: 

• Formaldehyde is determined and reported separately from total VOC — it is explicitly excluded from the VOC total per Subpart JJJJ. 

• Method 320 is a self-validating method with built-in spiking procedures to validate measurements from sources not previously validated. 

• Results reported in ppmvd on a dry basis, corrected to 15% O2 reference concentration. 

• Simultaneous measurement with NOx, CO, SO2, VOC, and moisture in a single test run, reducing on-site time and equipment requirements. 

Accurate measurement of stack gas volumetric flow rate is required to convert pollutant concentrations into mass emission rates (lb/hr). C&S applies the appropriate flow measurement method based on the source configuration. 

EPA Methods 1 and 2 (velocity traverse): 

• Method 1: Determination of the number and location of sampling traverse points based on stack diameter and upstream/downstream flow disturbances. 

• Method 2: Velocity measurements using a calibrated stainless steel S-type pitot tube connected to an inclined oil manometer. Stack temperature measured with a calibrated K-type thermocouple. 

• Volumetric flow rate calculated using Equation 2-8 and reported in acfm, wscfm, and dscfm. 

• Cyclonic flow check performed at the start of each test to verify flow uniformity. 

EPA Method 19 (F-factor method — for CHP systems): 

• Applied when CHP heat recovery boilers, added ductwork, rain caps, or diversion gates make direct velocity measurement impractical or non-representative of normal operation. 

• Uses fuel ultimate analysis and fuel heat content (HHV) combined with diluent gas concentration (O2 or CO2) measured by Method 3A to calculate flow using Equation 19-13 or 19-15. 

• Removes the effects of cyclonic flow within the duct and eliminates the need to confirm velocity measurement location requirements per Method 1. 

Opacity is a visual measurement of plume density expressed as percent light blockage. C&S conducts opacity observations by a certified Visible Emissions Evaluator (VEE) at 15-second intervals during representative operating periods. Results are documented on the EPA Method 9 Opacity Field Data Sheet and compared against EQB permit limits (typically 20% maximum opacity). Opacity testing is frequently required as a concurrent observation during performance tests for turbines, engines, and incinerators. 

Accurate O2 and CO2 measurements are the foundation of all emission rate calculations. C&S uses the Quantek Model 902P electronic gas analyzer for Method 3A measurements, simultaneously with all other sampling runs. 

The O2 measurement serves two critical functions: 

• Correction of pollutant concentrations to the reference O2 basis (15% O2 for engines and turbines, using the formula: Cr = Cm × (20.9 − r) / (20.9 − m)). 

• Input to exhaust flow calculations using Method 19 F-factor equations (O2-based: Qs = Fd × H × 20.9/(20.9−O2)). 

Calibration QA/QC: 

• Initial calibration error check: low, mid, and high EPA RATA-class calibration gases introduced directly to the CEM. Maximum allowable error: 2% of concentration. 

• System bias check at sample probe: difference between calibration-at-instrument and calibration-at-probe cannot exceed 3%. 

• System drift check after each test run: drift cannot exceed 3% of span. 

• Response time test performed during initial calibration to establish mean upscale and downscale response times. 

• Analyzers not adjusted during testing unless a system malfunction occurs; if recalibration is needed, the test run is restarted. 

C&S provides sampling services for the 187 HAPs designated by the EPA under 40 CFR Part 63, including metals, halogenated compounds, dioxins/furans, and semi-volatile organics. These services are applicable to incinerators, boilers, and industrial processes subject to NESHAP standards. 

• EPA Method 26A: Halogen gases and hydrogen halides (HCl, HF, Cl2) using water/alkaline impinger trains. Analysis by IC at NELAP-accredited laboratory. 

• EPA Method 29: Multi-metals (Pb, Hg, As, Cd, Cr, Ni, Zn) using acid impinger sampling trains. Analysis by ICP-MS or CVAA at NELAP laboratory. 

• EPA Method 101A: Specific mercury (Hg) sampling — elemental and oxidized forms. 

• EPA Method 23: Dioxins and Furans (PCDD/PCDF) using XAD-2 sorbent. Applicable to incinerators under 40 CFR Part 63 Subpart EEE. Analysis by HRGC/HRMS. 

• EPA Method 0030 (VOST): Semi-volatile organic HAPs using Tenax/silica adsorption tubes. Analysis by GC/MS.