Air Compliance Testing

2007-07-11T11:57:00.000-07:00

Ethanol Plant Emissions

Modern ethanol plants have been designed to incorporate a variety of emission control equipment to make the plants safe, efficient, and to control potential pollutants. It is important for project developers, and regulatory officials, to be familiar with the regulated pollutants.

Plant emissions may vary depending on process, design, plant type and feedstock. The typical ethanol production process includes feedstock delivery to the plant, feedstock handling and milling. During this process, tiny particles (particulate matter less than 10 microns in diameter, called PM10) are released into the air. PM10 is also emitted during the drying process. During fermentation, distillation and drying, volatile organic compounds (VOCs) are released. Some VOCs are known as hazardous air pollutants (HAPs). These include some or all of the following: acetaldehyde, acrolein, ethanol, formaldehyde, 2-furaldehyde, methanol, acetic acid and lactic acid. Potential emissions of these compounds must be measured and appropriate controls included in plant design regardless of the biofuel technology being considered. Carbon monoxide, nitrogen oxides, and sulfur oxides are also generated from combustion in the boilers at the plant. Carbon monoxide may also be generated in the drying process if such a process is included in the plant design. Modern emissions control equipment is included in most plant designs. However, potential emissions must be calculated and appropriate control strategies included in permit applications.

Other emissions may result from activities not associated with the production process. These may include: hydrogen sulfide and VOCs released from the wastewater treatment process; PM10 from the cooling towers; fugitive PM10 and VOC emissions from haul road traffic and equipment leaks, respectively; PM10, NOx, SOx, CO and VOCs from emergency equipment; and potential VOC evaporative loss emissions from the wet distillers grains solid storage piles if dryers are not in use at the plant.

Air Quality Permits
Virtually every state has enacted air quality regulations that require facilities with the potential to emit air pollutants above specified levels to obtain construction and/or operating permits. State regulations may vary in terms of permit requirements and the time-frame for authorizing and issuing permits. The project development team should confirm that the engineering firm or permit consultant with whom they may contract for these services is properly licensed in the state. The project development team should also review applicable work of the prospective firm(s) to determine relevant experience in these important areas. The project team should maintain an awareness of permit conditions and requirements that may affect plant operations initially, and in the future if plant expansion is contemplated.

Construction Permits
Before a new plant is built or an existing facility expands or modifies its plant, an air quality construction permit may be required. There are two types of construction permits: state and federal, known as Prevention of Significant Deterioration (PSD) permits. The type of construction permit needed will depend on the air pollutants that could be released from the new plant or expansion project.

Purpose
First and foremost, air quality construction permits are needed to protect the ambient air quality. Ambient air is the air outside of buildings that the general public has access to. The U.S. Environmental Protection Agency (EPA) has developed national ambient air quality standards (NAAQS) to protect the public health, welfare, and the environment. Predictive computer modeling is conducted prior to issuing construction permits to evaluate the potential impact the plant will have on the ambient air quality. A construction permit cannot be issued if the plant will cause or significantly contribute to violations of the ambient air quality standards. Construction permits also impose federally enforceable requirements that are recognized by the EPA.
Construction permits include emission and/or production limits that ensure air quality protection. The permits contain recordkeeping, reporting, monitoring, and testing requirements to ensure the plant is able to demonstrate that the permitted limits are met. The public is given notice that a construction permit may be issued and is given an opportunity to comment on activities that affect their environment. The public notice also provides an opportunity for communities to be educated about the environmental impacts of plants locating in their area.

State Construction Permits
Many states have had air quality construction permits in place since 1972 or earlier. In recent years, state permit requirements have been modified to reflect changes in the Clean Air Act Amendments of 1990. Facilities are typically required to obtain a construction permit before they construct, reconstruct or modify any air contaminant source or emission unit where there is a net increase in the potential-to-emit above prescribed quantities. Potential-to-emit (PTE) means the maximum emissions that would result from operating the source at full capacity 24 hours a day, 7 days a week, 52 weeks a year taking into consideration federally enforceable requirements.

Federal Construction Permits
EPA developed the federal construction permit program, known as the New Source Review Program, in 1977. Many states have incorporated the federal program into the state regulations and thereby maintain the authority to implement and enforce these rules. This program assures the following:

economic growth will occur in harmony with the preservation of existing clean air resources;
public health and welfare will be protected from adverse affects which might occur even at pollution levels below the ambient standards; and
air quality in areas of special natural recreation, scenic, or historic value, such as national parks and wildlife areas, will be preserved, protected and enhanced.

Under the New Source Review program there are two types of preconstruction permits. In areas that have pollution levels below the NAAQS, referred to as attainment areas, sources that meet the appropriate criteria will obtain a Prevention of Significant Deterioration (PSD) permit. In areas that have pollution levels above the NAAQS, referred to as nonattainment areas, sources meeting the appropriate criteria will obtain a nonattainment New Source Review permit.

In order for a facility to trigger the emission levels that require a PSD or New Source Review construction permit, they must meet both of the following criteria:

1) The facility must have the PTE of: 100 tons per year (tpy) of any criteria pollutant (PM10, NOx, CO, VOCs (used as an alternative to ozone), and Pb) if the source is one of 28 specific source categories listed in the PSD rules (40 Code of Federal Regulations (CFR) §52.21 (b)) OR 250 tpy of any criteria pollutant for sources not specifically listed in the PSD rules, and
2) Have net emissions increases of: 15 tons per year (tpy) of PM10, 40 tpy of SO2 or SO3 or any combination thereof, 40 tpy of NOx (calculated as NO2), 40 tpy VOC, 100 tpy CO, or 0.6 tpy Pb (lead).

Other pollutants with significant thresholds include total suspended particulate (TSP), fluorides, sulfuric acid mist, hydrogen sulfide (H2S), total reduced sulfur (TRS), and reduced sulfur compounds.

Chemical process plants are considered a major stationary source. It has been determined that ethanol plants are chemical process plants, so they are subject to the major stationary source requirements and the 100 ton per year threshold. A determination regarding production of other biofuels should be made during consultation with state permitting authorities. If a plant must obtain a construction permit under the PSD program, it must conduct a control device review and install BACT based on that review. The plant must also conduct an air quality review using computer modeling to assure that they will not exceed the NAAQS or impact areas of special natural recreation, scenic, or historical significance. As part of the air quality review, an increment analysis must also be performed. Increment is the portion of the ambient air that a facility is allowed to impact. This ensures each facility doesn’t excessively pollute the air and
affect future growth in the area. PSD permits may be subject to review by EPA, federal land managers, bordering states, and tribal organizations.

Operating Permits
An ethanol plant or any other type of biofuels plant may also need to obtain an air quality operating permit. There are two types of operating permits: major source (federal program) and minor source (state program). Again, the potential emissions from the plant will determine whether a facility must obtain a major or minor operating permit.

Purpose
The federal operating permit program, known as the Title V program, was created by the Clean Air Act Amendments of 1990 and was designed to create a "one stop" permit. The Title V operating permit compiles all of the applicable state and federal regulatory requirements, existing construction permit provisions, and recordkeeping, reporting, testing, and monitoring requirements into one permit. The intention behind listing everything in one permit is to assist facilities with maintaining compliance. Often times, a facility will have several construction permits for several pieces of equipment and it is difficult to keep track of all of the requirements in each permit. One permit with all of the facility’s requirements is intended to make it easier to track the requirements.

Public notification is also an important aspect of the operating permit program. The public is notified when an operating permit is proposed and is given the opportunity to comment during the 30-day public notice period. This gives the public the opportunity to become educated about the impacts that the facility may have on their environment. Many states have implemented comprehensive operating permit programs for facilities emitting certain air pollutants. Several states have taken the operating permit program one step further than the federal Title V operating permit program. The federal program only regulates larger facilities (or major sources) of air pollution while some state operating permit programs regulate both larger and smaller facilities (or minor sources) of air pollution.

Unlike a construction permit that must typically be obtained prior to construction and is generally valid for the life of the emission unit, an operating permit must usually be applied for within some period, often 2 months, after the facility begins operation. The operating permit may be issued for a specific period of time rather than the life of the operating unit. Project developers should contact state regulatory officials to determine specific permit requirements for the proposed project.

Permit Process
Project developers should take steps to understand the time requirements of the various permits required by federal, state and local authorities. Permits dictate the pace of project development, and permit conditions may affect the operating parameters of the plant. Permits are typically filed on behalf of the ethanol project development group by an environmental consulting firm. As noted previously, project developers should understand the time commitment for permit applications and the process that governs the review and content requirements of the applications. The best source of information is typically the regulatory agency staff. Staff members can provide details about specific information required for the proposed project.

General information about which the project developers should be aware is listed below.

Is it a new source or modification of an existing source?
If it is a modification, has the applicant provided information regarding the existing source?
Are all of the applicable forms complete with the appropriate information?
Have emission points been identified, described, and consistently named?
Does the plant diagram show heights and locations of all buildings, delineations of ambient air (e.g. property boundaries), and emission points?

Emissions Information

Are fuel types, fuel use, raw production materials, consumption, production rates, and operating schedules provided?
Have both actual and potential emissions of regulated air pollutants been provided?
Have the assumptions and calculations of the actual and potential emissions been included?
Are citations of emission factors included?
Can a major or minor source determination be made?
Is the project subject to Prevention of Significant Deterioration (PSD) review?

Control Methodology and Equipment

Has emission control equipment been identified and described?
Is supporting information on control equipment efficiencies included?
Did the facility propose limits on plant operation or work practices that may affect emissions?
If it is a PSD project, has a Best Available Control Technology (BACT) analysis been provided?

Monitoring, Recordkeeping, and Reporting

Have compliance monitoring devices or activities been identified and described?
Has the facility proposed testing of any emission units?
Did the facility provide information on existing or proposed recordkeeping practices?

Modeling

Is the project subject to modeling?
If yes, has a modeling protocol been submitted and approved?
Have the modeling inputs, assumptions, etc. been provided to the state regulatory agency on CD or diskette?
Was the modeling conducted in accordance with the approved protocol?
If it is a PSD project, have the ambient standards, PSD increment, and other impacts analyses been provided?

After a draft permit is filed, reviewed and approved, it is prepared for public notice. The public notice period generally includes an opportunity for public comments or public hearings. Project developers are advised to be attentive to potential sources of dissent and to take steps to mitigate concerns and questions about the project prior to the comment period. The permit process can be a lengthy period during which technical and community issues are discussed with project developers, technical consultants, regulatory officials and community representatives.

Permit Application Tips
State regulatory officials understand there is a significant volume of information required in construction and operating permit applications. In addition, wastewater treatment and drinking water permits will likely be required. Several tips that may make the process go more smoothly include:

Start early. Recognize the permit requirements and the time frame for permit issuance by federal, state and local authorities.
Talk with the regulatory agency staff. Communication is a key to a successful permitting process.
Make sure the permit application is complete and accurate. If plans change after you have submitted permit applications, you have an obligation to submit updated information, or face the risk of delays.
Address confidentiality issues appropriately, if such issues are important.
Include calculations and citations with your permit application. This information will assist the regulatory staff during permit review.
Research. Generally, ethanol plants are subject to various federal standards as well as state regulations. Federal requirements could influence your decisions regarding plant equipment. The issue of dryers at the plant is a recent example of permit issues influencing equipment choices.
Be aware of current regulatory issues. As the ethanol industry continues to expand throughout the nation and more emissions data is gathered, state agencies face new and often times challenging issues. Many of these issues are best dealt with during the early planning stages of the project.
Again, communication with state regulatory officials will help the project development group address these issues.
Get help. Although not required, state regulatory officials generally suggest that plant developers consult with people or companies that are familiar with the specific state requirements for permitting an ethanol plant. A qualified consultant that is familiar with the process and professional staff can help minimize the cost and time required for successful completion of the permit process. Familiarity and professional relationships can help move the permit process toward a successful completion in a timely fashion.

Permit Content
Construction permits and operating permits generally consist of the same basic elements. Each permit will contain general and specific conditions. Project developers should be generally familiar with the content and conditions of the permit. Working with and communicating with a qualified consultant is essential to this process. State regulatory officials can provide precise information about permit requirements.

Other Permitting and Compliance Issues
State regulatory officials monitor compliance of ethanol plants and other biofuel production facilities but compliance responsibilities ultimately rest with the plant owners and operators. Compliance issues can arise when the plant is constructed or operated in a fashion that differs from the conditions in the construction permit or operating permit. Common violations include failure to perform emissions testing, testing late, exceeding emissions or production limits, failure to keep adequate records, failure to submit required reports on time, and failure to conduct and keep records of control equipment maintenance. Following are a few tips that can help a facility maintain compliance, and reduce the potential for adverse economic consequences that may impact the plant owners.

Compliance Tips

Read and reread permit on a routine basis.
Understand permit requirements.
Keep records in one place and in a logical order.
Properly operate and maintain control equipment.
Designate an "environmental manager" and train a backup.
Ask state regulatory officials questions in order to get necessary information and to avoid misunderstandings and mistakes.
Plan ahead!
As noted, state and local regulatory agencies are the best source of information that is specifically applicable to an ethanol plant in the area. Information about federal permit requirements can be obtained from regional EPA offices and by visiting the EPA web site located at: http://www.epa.gov/.

From "A Guide for Evaluating the Requirements of Ethanol Plants", Developed by the Clean Fuels Development Coalition, the Nebraska Ethanol Board, and the U.S. Department of Agriculture, summer 2006.

2007-06-05T07:42:00.000-07:00

VOC Emission Measurement Methods

1.0 INTRODUCTION
Individual pollutant emissions from a wide variety of industrial processes are measured by a limited number of source sampling methods. Volatile Organic Compounds (VOCs) present a particularly unique testing dilemma since there are a large number of different compounds defined as VOCs. The process of accurately and consistently measuring the quantity of total VOCs emitted is a concern to both industry and regulatory agencies.

The most commonly used methods for quantifying VOCs in gas streams are in the Code of
Federal Regulations (40 CFR 60) Appendix A, Methods 18, 25, and 25A. Each method has advantages and disadvantages relative to the other methods. The choice of measurement and reporting techniques depends on the purpose that the data will serve. Due to differing analytical limitations for each of the VOC test methods, all sources may not be able to use the same test method and data manipulation procedures.

2.0 VOC EVALUATION REQUIREMENTS
Many industrial facilities emit a pollutant termed Volatile Organic Compounds (VOCs). VOCs are an air quality concern primarily because they are a precursor for tropospheric ozone formation. The control of VOC costs industry millions of dollars a year. Measuring the effects of control as well as the quantification of total VOC emissions (tons/yr) is typically performed using emission measurement test methods commonly referred to as 'Stack Testing'. The possibility of error in VOC quantification due to the test methods or the reporting units could be a major concern for industry and regulatory agencies.

There are three primary mechanisms for evaluating VOC emissions:
1) Material Balance - A material balance estimates the outlet pollutant emissions based on the process inputs. Coating industries are the prevalent source category to use this mechanism. By manipulating data such as the VOC content of coatings, the quantity of coatings used per product, and the quantity of product produced over a period of time, the VOC emissions of a source can be estimated. If a source requests a reduction of the reported emissions due to control equipment, usually a reasonable control efficiency will be applied or a control efficiency test will be required.

2) Emission Factors - Overall, emission factors for VOCs are not widely used for permitting or compliance purposes in North Carolina. The use of the emission factors may be appropriate to determine if estimated emissions are significantly lower than regulatory limits, but otherwise a material balance or source test is employed.

3) Emissions Testing - Testing is typically the most preferred source of emissions data from a specific source. Test data is a good representation of emissions from the source if the test is performed correctly and the emissions are reported in the correct units.

2.1 Regulations
Industrial facilities constantly test their air pollutant emissions. One of the primary reasons for emissions testing is to provide proof of compliance with applicable regulations. Sources are required to demonstrate compliance with VOC emission limits that may be expressed as a concentration, a control efficiency, or a mass emission rate. The units for VOC emission limits will vary depending on the source category, the age of the source, the location of the source, and the regulating agency. Therefore, the requirements for VOC measurements, via testing, may include reporting the emissions on a mass rate. However, the VOC methods in 40 CFR 60 Appendix A, Methods 18, 25, and 25A (M18, M25, M25A), may not provide an accurate mass emission measurement as the methods are currently applied. Correctly defining the intentions of the measurement test, what pollutant group should be measured, and what pollutant group the methods can measure is crucial to the VOC measurement problem.

2.1.1 Concentration Limits
A concentration based VOC standard is often listed as parts per million corrected to a percentage of diluent flue gas such as oxygen (i.e. ppm @7% O2). The standard has usually been defined by the same test method that will be used to prove compliance with the standard. This means that experimental data has been compiled that will help determine the limit or determine if the limit is measurable. The same methodology that was used to measure emissions for determining a limit will also be used to prove compliance with the limit.

2.1.2 Control Efficiency Limits
Control efficiency is defined as the amount of pollutant that is created or that would be exhausted to the atmosphere uncontrolled in comparison to the amount of pollutant exhausted to the atmosphere after an air pollution control device (APCD). The determination of control efficiency will include the amount of capture for a control system. The capture efficiency is defined as the percentage of process gas that enters the APCD compared to the total amount of untreated process gas. By testing the flue gas, before and after the APCD, and considering the capture efficiency, the total control efficiency can be calculated. (Rich, G.A., 1991)

2.1.3 Mass Emission Limits
Mass emission reporting is most often stipulated in regulations such as Prevention of Significant Deterioration (PSD), State Implementation Plans (SIP), and for emissions inventories. A mass emission rate is typically reported in terms of pounds per hour (lb/hr) or some derivative of mass per time. For any pollutant emission, the mass emission can be determined by sampling the gas stream for a representative concentration of the pollutant. The concentration is then combined with the flow rate and the molecular weight (MW) of the pollutant to determine the mass emissions. The effluent flow rate is evaluated through other stack testing methods and the MW should be known for the pollutant. (An example is sulfur dioxide, SO2, with a MW of 64 lb/lbmol.) However, VOCs are defined in 40 CFR 51.100(s) as " any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions." 40 CFR 51 is the SIP / PSD section of the CFR and contains a list of the federally exempted VOCs. Based on this definition of VOCs, there are an innumerable amount of different VOCs, all with differing MWs. Therefore, no single MW can be used to fully characterize mass VOC emission rates.

3.0 VOC TERMINOLOGY
The terms and definitions used to describe organic compound emissions vary depending on the context in which they are used. The term Total Organic Compounds (TOC) would seem to indicate the quantification of all organic compounds in an effluent stream. However, even the EPA defines TOC differently dependent on which publications are cited. The emissions estimate manual, AP-42, defines TOC as all VOCs and all exempted VOC compounds. In contrast, certain New Source Performance Standard (NSPS) subparts dealing with the Synthetic Organic Chemical Manufacturing Industry (SOCMI) define TOC by the specific chemicals that may be present in that process or all compounds quantified by the measurement techniques, except that: "..those compounds which the Administrator has determined do not contribute appreciably to the formation of ozone are to be excluded." The apparent discrepancy with these definitions deals with the measurement techniques.

The SOCMI subparts require a M18 which reports speciated VOC quantification in terms of the compound, 'as VOC'. M25 or M25A will generate total VOC emission rates usually in terms of carbon. Without speciation, the fraction of exempted VOCs in the TOC measurement is unknown.

AP-42 is the EPA document listing air pollutant emission estimates for industrial processes. This compilation of emission estimates was created through the use of testing data, operational information, mass balance and other sources. AP-42 defines VOCs under three broad headings: TOC, Total Non-Methane Organic Compounds (TNMOC), and individual speciated organic compound listings. The data presented in AP-42 can be analyzed to determine the procedure used to create the factor. In general, when a TOC rate is for all compounds, then the testing was most likely M25A. When the data is presented as TNMOC, due to the analytical steps, then the estimate is the result of M25 testing. When the data in AP-42 is presented as speciated compound rates, then the testing was likely performed by M18. In earlier editions of AP-42 the data for TOC is often presented 'as carbon' or 'as methane' which is a clear indicator that M25A was the origin of the data.

The correct determination of VOC emission rates is dependant on multiple factors. One factor is the ultimate purpose of the data. If testing is performed for regulatory purposes, then the regulating agency must define the pollutant and the reporting units. For PSD mass emission rate reporting, VOCs must be quantified as all organic compounds (except those listed in the 40CFR51 VOC definition) and the total weight of the molecules of the organic compounds.

Although speciation and quantification of individual organic compounds is not required, more information about the gas stream will be necessary in order to use the correct methodology for testing. Possibly the most difficult factor is the sampling and analytical capability of the available methods. (Crumpler, D., 11/26/96)

4.0 VOC TEST METHODOLOGY
A brief discussion of M18, M25, M25A should explain the positive and negative attributes of each method. The analytical capabilities will be influential in describing the appropriateness of each method. Each individual method has limits of performance and may not be as applicable as another method in particular circumstances.

4.1 Method 18
M18 is the reference method for VOC analysis using a gas chromatograph (GC). The method is a guideline and a system of quality assurance checks (QA) for the VOC analysis rather than a rigorous, explicit manual for sampling. The method is flexible on the choice of collection media as long as the QA requirements are met. Often sampling is performed using NIOSH (National Institute of Occupational Safety and Health) methods or a Volatile Organic Sampling Train(VOST). A sample gas stream can be extracted from the source and then routed through a collection material upon which the VOCs will be deposited. Typical materials are Tenax tubes, or charcoal tubes. The gas stream may also be analyzed by direct interface with a GC. Moisture content (H2O) is a difficulty with most VOC methods due to the solubility of VOCs and other moisture induced problems. The GC analysis is performed by separating and identifying individual VOC compounds and then quantifying the compounds using a detector. The separation is performed by injecting the gas stream into a GC column. The elution times, the amount of time a specific compound takes to travel through the column, can be determined experimentally using organic compound calibration standards.

Once a compound in the gas stream can be identified, the compound is then quantified in the detector portion of the analyzer. A Flame Ionization Detector (FID), which will be thoroughly described in the M25A section, is common in GCs. For GC methods, standards are typically used to calibrate the instrument for the specific compound of interest. Due to the specific compound calibration, the pollutant quantification should be accurate. However, this requirement is also a negative for M18 since there is an implicit requirement to know what specific compounds are present in the sample and a rough estimate of their quantities. If testing is being performed on either a combustion process, a source with no previous process emission data, or a highly variable VOC process, then the sampling should be done in a two tier fashion. An initial test would perform a screen for identifiable VOCs, possibly using a GC/MS (mass spectrometry), and then the actual quantification test would be performed. Knowing the type of organic compounds present will dictate the correct sampling and analysis procedures.

M18 is ideal when the quantity of speciated organic compounds must be known. The M18 data may be reported as a concentration or on another basis using additional facility or effluent data.

For the quantification of TOC from a source that does not have a VOC characterization, M18 can be time intensive and extremely costly. The possibility of multiple sampling scenarios is a concern. The analysis cost can easily escalate with multiple calibration standards and laboratory fees for each sample or compound quantification.

4.2 Method 25A
M25A is a derivative of M25, but will be discussed first in order to understand the analytical procedure. Method 25A was created in order to make VOC quantification easier, yield real-time results, and provide a method to compensate for the detection limits of M25. M25A also introduces extra biases and problems. The method details the sampling, analysis and calibration of the VOC test system. Sampling is accomplished by extracting a gas stream from the effluent and transferring it via heated non-reactive tubing to the analyzer. The sample line is heated in order to prevent any moisture in the effluent from condensing. Once the gas sample reaches the analyzer, it is injected into the FID under very controlled temperature and pressure conditions.

The FID analysis is a great concept, but creates reporting problems. The FID is composed of a chamber with electric current detecting plates and a flame. The flame is typically created through the combustion of hydrogen and oxygen. The detecting plates are oppositely charged in order to create a potential difference across them. By injecting a gas into the FID, the VOCs will be combusted by the flame. The chemistry that occurs in the flame is confusing, depends on the sample matrix and is not entirely understood. (Teco, 11/24/96) Most of the theory for FIDs comes from experimentation.

Essentially, the carbon radicals in the flame have an ionization. The ionization is measured by the detector plates through a decrease or increase of amperage across the detector. (McAlister, G., 11/26/96) The positive attributes for M25A include the ease of sampling and analysis, real time emission measurement, and lower cost. The M25A sampling system can deal with H2O in the effluent since the sample is transported above the condensation temperature. The FID can operate at levels of H2O up to approximately 40% prior to the flame being extinguished. (EPA, 6/1977).

The negative attributes of M25A are at the core of VOC reporting difficulties. The FID measures the quantity of carbon ions, and is typically calibrated by a standard of methane (CH4) or propane (C3H8). The FID will give a response relative to the calibration standard. The VOC stream quantified is then reported in terms of 'as carbon', 'as methane', or 'as propane'. This procedure will involve two errors: response factors and total VOC molecular weight. The response factor is the ratio of the actual concentration of the VOC to the instrument reading. Response factors are dependent on the detector and on the sample gas matrix so it is difficult to actually determine correct response factors for all sampling situations. Without compensating for the response factor, the reported VOC concentration can be under or over quantified. Response factor difficulties typically arise when chlorine (Cl) or oxygen (O) atoms are present in the VOC molecule. It is theorized that the Cl and O atoms have a tendency to recombine with the carbon ions prior to ionization quantification or that the Cl and O atoms will alter the charge of the carbon atoms thereby suppressing the response. Other atoms may also affect the carbon ions in a similar manner. It is also possible that other radicals in the flame zone will have ionic charges and therefore register on the detector which would yield an increased response. (McAlister, G., 10/24/96) Published response factors exist for some compounds, however, response factors are unique to a FID.

Another negative attribute concerns the FID analysis and the reporting technique. Since a FID measures the quantity of carbon ions relative to a standard, the VOC compound is not identified. It is not a requirement that the individual VOCs be quantified, but in order to convert a concentration to a mass rate, the MW of the compound must be known. An average molecular weight of the gas stream can be used, but in order to calculate an average MW, the relative concentrations of specific VOCs must be known. Without an average MW, the data is often reported on a mass basis 'as carbon' or in terms of another surrogate. Since M25A should measure the number of carbons in a compound, the MW of the compound should be divided by the number of carbons in the molecule to get a carbon weighted MW.

However, since the individual VOC compounds often are not characterized, the relative percentages of VOCs and an average MW is not known. As an example of the error introduced to the mass emission rate by the use of the MW for carbon, consider Propylene Glycol (CH3C(OH)CH2OH). The MW for this compound is 76.10. The carbon weighted MW is 76.1/3=25.4. If we assume a concentration of 100ppm and a Qsd of 100,000dscfm then lb/hr 'as carbon'= 18.7 lb/hr. Assuming the same concentration and flow rate but using the MW normalized for carbon we get lb/hr 'as VOC'=39.57 lb/hr. An error in excess of 100% due only to MW.

M25A is a good method to use with low VOC concentrations. M25A is also an efficient method when proving compliance with a VOC concentration standard, provided the standard was defined by M25A, or when determining a control efficiency (CE). Since the mass rate is not required for CE, the APCD inlet and outlet concentrations can be used to determine CE. A concern with a M25A CE determination is the type of control device. A combustion device will change the composition of the effluent and possibly add new VOCs. Since FIDs may yield differing response factors before and after the combustion device, the results may be skewed. Also, a removal device may be more efficient in removing one specific type of VOC and also skew the results due to differing relative percentages of VOCs in the stream before and after the APCD and due to differing response factors. However, the effect of the control device is often ignored when measuring CE in favor of minimizing the necessary testing.

4.3 Method 25
Method 25 is used to determine the TNMOC concentration. It measures non-methane organics
due to part of the analysis procedure. Sampling is performed using an evacuated stainless steel
cylinder and a condensate trap. The condensate trap is utilized in order to prevent moisture from entering the cylinder. The sample must be conditioned properly prior to analysis and the actual sampling can be problematic due to the location and effluent conditions.

The sample is ultimately injected into a GC column which removes CH4, carbon monoxide
(CO), and carbon dioxide (CO2) from the sample. The remainder of the sample, which should contain the non-methane hydrocarbons, is oxidized to CO2. The CO2 is then reduced to CH4. The CH4 will then be measured by a FID. The purpose for the oxidation / reduction steps is to eliminate any response factor differential. The FID can be calibrated using methane and then quantify the sample stream in terms of methane.

One benefit of M25 is the absence of the response factor problem that plagues M25A. The
negative attributes of M25 are numerous. The method is sensitive to H2O and CO2 which can have combined effects. Typically if the percentage of CO2 multiplied by the percentage of H2O is greater than 100, then M25 will not function very well. The method also has a high minimum detection limit (MDL) of 50ppm. Often testing companies and regulatory agencies accept 100 ppm as the MDL. This fact often eliminates the use of M25 for control efficiency testing since the outlet concentration of an APCD may be below 100ppm (McAlister 1/91). Due to the expertise required for accurate sampling and complicated analysis, the M25 test is often more expensive than a M25A test. There also appears to be difficulties with meeting the audit sample requirements. Two audit samples provided by the regulating agency should be analyzed within 20% of the audit sample concentration. Data suggests that the 20% error limit is often surpassed and may not be realistic. (Mitchell, 2/95)

Ultimately, the method still does not yield the mass weight rate of the VOCs. In order to report
a mass emission rate, the MW of the VOC must be known. If the gas stream contains only one VOC, then the MW for that one VOC can be used for the mass calculation. If the gas stream contains multiple VOCs, which is the most common case, then the relative percentage of VOCs must be known in order to calculate an average MW. Again, knowing the relative percentages of individual VOCs is a problem when the gas stream is uncharacterized. The applicability section of Method 25 states:
"Direct measurement of an effluent with a flame ionization detector (FID) analyzer may be appropriate with prior characterization of the gas stream and knowledge that the detector responds predictably to the organic compounds in the stream."

4.4 VOC Method Summary
In summary, the three most prominent methods for VOC testing are M18, M25, and M25A.
M18 is excellent for speciating individual compounds, testing for Toxic Air Pollutants (TAPs) and
Hazardous Air Pollutants (HAPs), for mass emission tests when there are only a few VOCs in the gas stream, and for characterizing a gas stream. M25 is useful for proving compliance with set
concentration limits, such as the limits in several NSPS. M25 can be used for mass emissions when the prerequisites are satisfied. M25A is useful when the concentration of VOCs is below 100ppm and can also be used for mass emissions with the prerequisite VOC characterization and response factor compensation.

The concepts of method precision and accuracy are defined for M18. Duplicate analyses should be within 5% of their mean value while the accuracy of M18 should be within 10% of the actual value for a calibrated organic. M25 and M25A do not discuss precision and accuracy possibly
due to the analytical limitations. Discussing precision and accuracy in terms of the concentration of carbon measured compared to the actual amount of VOCs emitted does not make sense. Beyond the precision and accuracy of the methods, the errors associated with response factors and incorrect molecular weight can greatly underestimate the emissions of VOCs. It would be difficult to determine this amount of error due to a lack of published data, the variability of sources, and variable analytical responses. More testing, performing M18, M25 and M25A simultaneously as well as any other validated VOC test, needs to be done so that the data can be analyzed to determine source specific correction factors. The associated costs of such projects may be prohibitive.

An emerging technology that may someday eliminate the VOC testing and reporting problem
is FTIR testing. FTIR (Fourier Transform Infrared) testing utilizes the identification of a chemical compound through the use of spectral patterns that are unique to the compound. While FTIR testing may one day be the reference, currently there is not an approved FTIR method. The cost from possibly having to validate a source specific test along with the associated costs of emerging technology has not allowed widespread use of FTIR. (Entropy, 11/20/96)

Excerpted from "VOC Emissions: Influence of VOC Measurement and Reporting Methods on
Regulatory Policy and Emissions Estimations" NC Division of Air Quality Stationary Source Compliance Branch, Michael Pjetraj December 6, 1996

2007-05-10T13:51:00.000-07:00

OSHA Compliance Monitoring

Why Monitor your Employees?
Protecting employees from adverse health effects due to chemical, biological, and physical hazards is important to businesses for many reasons:
• Proactive evaluation and prevention of workplace hazards
• Resolving employee concerns about their environments
• Assessing the effectiveness of engineering controls
• Selecting appropriate personal protective equipment
• Investigating occupational disease claims
• Complying with Federal and State regulations

How We Can Help
Air ComplianceTesting is equipped to perform air sampling for nearly all classes of chemical contaminants. We offer both personnel and area air monitoring services, using both active and passive sampling techniques. Real-time monitoring is available formany contaminants. We can performsampling formost organic and inorganic vapors and particulates. We have experience sampling for ozone, trace metals, asbestos, volatile organics, and microbiological contaminants (e.g. mold and various bioaerosols).

Health Hazard Assessments
Air ComplianceTesting provides walk-through surveys and personnel interviews as well as personal and area onsite testing of hazardous environmental conditions (e.g. Carbon Dioxide, temperature, humidity).

IndustrialWorkplace Assessments
Our comprehensive worker exposure monitoring programs includes test method recommendations and equipment specifications including those from:
• The Occupational Safety & Health Administration (OSHA)
• The National Institute for Occupational Safety and Health (NIOSH)
• American Society forTesting and Materials (ASTM)
• Environmental Protection Agency (EPA)
• Other custom methods as necessary.

Results can be compared with established occupational exposure limits such as:
• OSHA 8-hourTimeWeighted Average (TWA) Permissible Exposure Limits (PEL) and Short-term Exposure Limits (STEL),
• American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLV),
• NIOSH Recommended Exposure Limits (REL), or
• Other employer defined limits.

For more information, go to www.aircomp.com.

2007-05-10T13:40:00.000-07:00

Dispersion Modeling

Dispersion modeling uses mathematical formulations to characterize the atmospheric processes that disperse a pollutant emitted by a source. Based on emissions and meteorological inputs, a dispersion model can be used to predict concentrations at selected downwind receptor locations. These air quality models are used to determine compliance with National Ambient Air Quality Standards (NAAQS), and other regulatory requirements such as New Source Review (NSR) and Prevention of Significant Deterioration (PSD) regulations. These models are addressed in Appendix A of EPA's Guideline on Air Quality Models (also published as AppendixW of 40 CFR Part 51).

Our approach to Dispersion Modeling:
Air Compliance Testing will start by collecting all needed information about the facility, such as point parameters, exact locations, and emission rates. Our next step is to perform preliminary modeling (screening) to determine whether refinedmodeling is required. If it is, then we will perform a refined modeling analysis according to the guidelines of the state in which the facility is located. Our finished report to you will be suitable for submittal to the agency.

Dispersion Modeling Can Be Used During Your Permitting Process:
• To verify that emissions from a new source will not exceed ambient air quality standards, or maximum ground level, fence line concentrations (AirToxics requirements).
• To determine appropriate stack configuration and/or additional control requirements.
• To predict future pollutant concentrations from multiple sources.
• To perform, Air Quality Impact Studies.
• To evaluate the effect of building downwash.
• To analyze deposition patterns.

Modeling can be a very cost-effective approach:
• When preliminary calculations indicate the need for excessively high stack heights that would be expensive to install;
• When multiple discharges from stacks and vents are present;
• When a better understanding of the impact of discharges is required.
• When management controls are needed to minimize odor impacts. Dispersion Modeling can determine the conditions under which odor complaints are likely to occur, which can be used to plan a mitigation strategy;
• When the impact of changes in emissions, emission controls or stack heights are being assessed. Potential changes can be input into the model to see the effect on the dispersion pattern.

Additional Dispersion Modeling Services:
Accidental Release Modeling
Accidental releases can include scenarios such as toxic gas or liquid spill releases, or overpressure explosions. The nature of the release, including the substance and the emission rate, and the type of release dictate the most appropriate model for calculating downwind concentrations.

Engineering/Business Assessments
Dispersion modeling is ideal for performing “what-if ” analysis to determine the effects of potential operational changes. By performing a series of model runs, Air ComplianceTesting can help you with plant and equipment siting, stack height design, and evaluation of control equipment options.

A Few Of Our Modeling Tools:
Toxins Screening Model (TSCREEN) - A Gaussian model that implements the procedures to correctly analyze toxic emissions and their subsequent dispersion from one of many different types of possible releases for superfund sites. It contains 3 models: SCREEN3, PUFF, and RVD (Relief Valve Discharge).

AERMOD Modeling System - A steady-state plume model that incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concepts, including treatment of both surface and elevated sources, and both simple and complex terrain.

CALPUFF Modeling System - A non-steady-state puff dispersion model that simulates the effects of time- and space-varying meteorological conditions on pollution transport, transformation, and removal. CALPUFF can be applied for long-range transport and for complex terrain.

The SLAB model treats denser-than-air releases by solving the one-dimensional equations of momentum, conservation of mass, species, and energy, and the equation of state. SLAB handles release scenarios including ground level and elevated jets, liquid pool evaporation, and instantaneous volume sources.

Go to www.aircomp.com for more information.

2007-01-22T09:36:00.000-08:00

FTIR Field Testing Report Links

FOURIER TRANSFORM INFRARED (FTIR) METHOD VALIDATION AT A COAL-FIRED BOILER
This report describes results of the Fourier transform infrared (FTIR) method field validation test that was conducted at a coal-fired boiler facility. The validation test was conducted from January 25 to February 10, 1993 by Dr. Grant M. Plummer, Mr. Scott A. Shanklin, Mr. Greg C. Blanschan, Dr. Thomas A. Dunder, Dr. Thomas J. Geyer, Ms. Lisa M. Grosshandler, Dr. Ed Potts, Ms. Patricia Royals, Mr. Rick Strausbaugh, and Mr. Mike Worthy, of Entropy Environmentalists, Inc., under U.S. EPA Contract No. 68D20163, Work Assignment No. 2.
FTIR spectrometry is of interest in emissions testing because of its usefulness in performing multicomponent gas analyses. Because each distinct molecular structure possesses a distinct infrared absorption spectrum, FTIR instruments can provide quantitative and qualitative information on the composition of sample gases. This aspect of the technique, along with its potential for providing near-real-time analytical results, is particularly important considering the number of hazardous air pollutant (HAP) compounds listed in the Clean Air Act Amendment of 1990.

Report Conclusions: The FTIR spectrometric analytical procedures described in this report have been subject to a test for validity according to a revised form of EPA Method 301, in which the option for (dynamic) analyte spiking was chosen. On the basis of these tests and the prescribed statistical calculations, the methodology is to be considered "valid" for a number of compounds in three different sampling systems. The number of compounds considered "valid" for each sampling system, and the approximate in-stack concentration corresponding to the spike concentration level, are summarized below.
23 compounds for hot/wet sampling, at 10 ppm.
24 compounds for condenser sampling, at 10 ppm.
11 compounds for concentrated samples, at 500 ppb.
With the exception of m-xylene, all compounds which met the validation criteria in concentrated samples also passed for either the hot/wet or condenser samples. 15 compounds are considered validated for both the hot/wet and condenser sampling systems. 32 different compounds are considered valid for at least one sampling system, as well as a total of 58 compound/sampling system combinations.
The test procedures differed from those prescribed in Method 301 in the following ways:
Gas phase samples were collected sequentially, rather than simultaneously.
The required number of samples (24) was not obtained for all gas phase spike compounds, and fewer than the required number were obtained for all sample concentration spike compounds.
Gas phase samples were spiked dynamically at 20% of the sample volume.
The equivalent spike levels (10 ppm for gas samples, 500 ppb for concentrated samples) did not approximate the emission level in the effluent.
Further testing may be warranted for extension of concentration to high-boilers (via addition of cryo-trapping), extension of gas phase sampling to particular reactive species (e.g. HCl, HF), and to compounds for which cylinder gas standards cannot be prepared.

GAS-FIRED BOILER EMISSION TEST REPORT
The U.S. Environmental Protection Agency (EPA), Office of Air Quality Planning and Standards (OAQPS), Industrial Studies Branch (ISB), and Emission Measurement Branch (EMB) directed Entropy, Inc. to conduct an emission test at Houston Lighting and Power Company's (HLPC) Greens Bayou electric generating station, Unit 5, gas-fired boiler in Houston, Texas. The test was conducted on May 20 and 21, 1993. The purpose of this test was to identify which hazardous air pollutants (HAPs) listed in the Clean Air Act Amendments of 1990 are emitted from this source. The measurement method used Fourier transform infrared (FTIR) technology, which had been developed for detecting and quantifying many organic HAPs in a flue gas stream. Besides developing emission factors (for this source category), the data will be included in an EPA report to Congress.

Report Conclusions: This represents the first attempt to use FTIR spectroscopy in such an ambitious test program. The program accomplished very significant achievements and demonstrated important and fundamental advantages of FTIR spectroscopy as an emissions test method: Using a single method quantitative data were provided for over 100
compounds.

Software was written to analyze a large data set and provide
concentration and detection limit results quickly. The same or
similar software can be used for subsequent tests with very little
investment of time for minor modifications or improvements.

The original data are permanently stored so the results can be
rechecked for verification at any time.

A single method was used to obtain both time-resolved (direct gas)
and integrated (sample concentration) measurements of gas streams
from two locations simultaneously.

The two techniques of the FTIR method cover different concentration
ranges.

Preliminary data (qualitative and quantitative) are provided on-site
in real time.

With little effort at optimization (see below), detection limits in
the ppb range were calculated for 29 HAPs and less than 5 ppm for 70
HAPs using direct gas phase measurements of hot/wet samples, which
present the most difficult analytical challenge. Sample
concentration provided even lower detection limits for some HAPs.

A compound detect is unambiguous.

FUEL OIL FIRED ELECTRIC UTILITY BOILER EMISSION TEST
The U. S. Environmental Protection Agency (EPA) Office of Air Quality Planning and Standards (OAQPS), Industrial Studies Branch (ISB), and Emission Measurement Branch (EMB) directed Entropy, Inc. to conduct an emission test at the Unit 1 oil-fired boiler at Long Island Lighting Company's (LILCO) electric generating station in Northport, New York. The test was conducted on July 19 to July 21, 1993. The purpose of this test was to identify which hazardous air pollutants (HAPs) listed in the Clean Air Act Amendments of 1990 are emitted from this source. The measurement method used Fourier transform infrared (FTIR) spectrometry, which had been developed for detecting and quantifying many organic HAPs in a flue gas stream. Besides developing emission factors (for this source category), the data will be included in an EPA report to Congress.

Report Conclusions: This program represents the first attempt to use FTIR spectroscopy in such an ambitious test program. The program accomplished very significant achievements and demonstrated important and fundamental advantages of FTIR spectroscopy as an emissions test method over other test methods:
Using a single method quantitative data were provided for over 100
compounds.
Software was written to analyze a large data set and provide
concentration and detection limit results quickly. The same or
similar software can be used for subsequent tests with very little
investment of time for minor modifications or improvements.
The original data are permanently stored so the results can be
rechecked for verification at any time.
A single method was used to obtain both time-resolved (direct gas)
and integrated (sample concentration) measurements of gas streams
from two locations simultaneously.
The two techniques of the FTIR method cover different concentration
ranges.
Preliminary data (qualitative and quantitative) are provided on-site
in real time.
With little effort at optimization (see below), detection limits in
the ppb range were calculated for 21 HAPs and between 1 and 5 ppm for
65 other HAPs using direct gas phase measurements of hot/wet samples,
which present the most difficult analytical challenge. Sample
concentration provided even lower detection limits for some HAPs.
A compound detect is unambiguous.

COAL-FIRED BOILER EMISSION TEST
The U. S. Environmental Protection Agency (EPA) Office of Air Quality Planning and Standards (OAQPS), Industrial Studies Branch (ISB), and Emission Measurement Branch (EMB) directed Entropy, Inc. to conduct an emission test at New York State Electric and Gas Company's (NYSEG) Kintigh Station (Site 12), a coal-fired electric generating unit in Somerset, New York. The test was conducted from July 26 to July 29 1993. The purpose of this test was to identify which hazardous air pollutants (HAPs) listed in the Clean Air Act Amendments of 1990 are emitted from this source. The measurement method used Fourier transform infrared (FTIR) technology, which had been developed for detecting and quantifying many organic HAPs in a flue gas stream. Besides developing emission factors (for this source category), the data will be included in an EPA report to Congress.

Report Conclusions:This represents the first attempt to use FTIR spectroscopy in such an ambitious test program. The program made significant achievements and demonstrated some important and fundamental advantages of FTIR spectroscopy as an emissions test method: Quantitative data were provided for a large number of compounds
using one method.

Software was written to provide concentration and detection limit
results in a timely manner. The same or similar software can be
used for subsequent tests with very little investment of time for
minor modifications or improvements.

Preliminary data (qualitative and quantitative) is provided on-site
in real time.

With little effort at optimization (see below), detection limits in
the ppb range were calculated for 25 HAPs and below 5 ppm for a
total of 75 HAPs using direct gas phase measurements. Sample
concentration provided even lower detection limits for some HAPs.

A positive identification of a compound is unambiguous.

COAL-FIRED FLUIDIZED BED BOILER EMISSIONS TEST
The U. S. Environmental Protection Agency (EPA) Office of Air Quality Planning and Standards (OAQPS), Industrial Studies Branch (ISB), and Emission Measurement Branch (EMB) directed Entropy, Inc. to conduct an emission test at Texas-New Mexico Power Company's (TNP) Unit 2 fluidized bed coal-fired boiler, in Hammond, Texas. The test was conducted from May 10 to May 13, 1993. The purpose of this test was to identify which hazardous air pollutants (HAPs) listed in the Clean Air Act Amendments of 1990 are emitted from this source. The measurement method used Fourier transform infrared (FTIR) technology, which had been developed for detecting and quantifying many organic HAPs in a flue gas stream. Besides developing emission factors (for this source category), the data will be included in an EPA report to Congress.

Report Conclusions: The gas phase system detected water vapor, CO2, CO, SO2, NO, and NO2. Sample concentration detected formaldehyde, ammonia, HCl, SO2, HCN, methane, hexane, and a cyclic siloxane compound. Ammonia was also detected in the ambient samples collected at the stack. Some absorbance bands remain unidentified.

COMBINED CYCLE GAS-FIRED GAS TURBINE EMISSIONS TEST
The U. S. Environmental Protection Agency (EPA) Office of Air Quality Planning and Standards (OAQPS), Industrial Studies Branch (ISB), and Emission Measurement Branch (EMB) directed Entropy, Inc. to conduct an emission test at Houston Lighting and Power Company's (HLPC) T. H. Wharton Electric Generating Station combined-cycle gas-fired gas turbine in Houston, Texas. The test was conducted on May 17 and 18, 1993. The purpose of this test was to identify which hazardous air pollutants (HAPs) listed in the Clean Air Act Amendments of 1990 are emitted from this source. The measurement method used Fourier transform infrared (FTIR) technology, which had been developed for detecting and quantifying many organic HAPs in a flue gas stream. Besides developing emission factors (for this source category), the data will be included in an EPA report to Congress.

Report Conclusions: This represents the first attempt to use FTIR spectroscopy in such an ambitious test program. The program accomplished very significant achievements and demonstrated important and fundamental advantages of FTIR spectroscopy as an emissions test method:
Using a single method quantitative data were provided for over 100
compounds.

Software was written to analyze a large data set and provide
concentration and detection limit results quickly. The same or
similar software can be used for subsequent tests with very little
investment of time for minor modifications or improvements.

The original data are permanently stored so the results can be
rechecked for verification at any time.

A single method was used to obtain both time-resolved (direct gas)
and integrated (sample concentration) measurements of gas streams
from two locations simultaneously.

The two techniques of the FTIR method cover different concentration
ranges.

Preliminary data (qualitative and quantitative) are provided on-site
in real time.

With little effort at optimization (see below), detection limits in
the ppb range were calculated for 26 HAPs and between 1 and 5 ppm for
77 other HAPs using direct gas phase measurements of hot/wet samples,
which present the most difficult analytical challenge. Sample
concentration provided even lower detection limits for some HAPs.

A compound detect is unambiguous.

2007-01-22T09:25:00.000-08:00

FTIR Technology (From: Technology Transfer NetworkEmission Measurement Center)

The Emission Measurement Center (EMC) at EPA has been investigating the application of Fourier Transform Infrared Spectroscopy (FTIR), to emissions monitoring. The FTIR technology shows promise since it has the capability to measure more than 100 of the 189 Hazardous Air Pollutants(HAPs) listed in Title III of the Clean Air Act Amendments of 1990 (CAAA).Upon passage of the CAAA, measurement methods existed for only 40 of theHAPs. The FTIR has the capability of measuring multiple compounds simultaneously, thus providing an advantage over current measurement methods which measure only one or several HAPs; FTIR Methods can provide a distinct cost advantage since it can be used to replace several traditional methods(cost savings can vary depending on the number of compounds present).

Method 318 - Extractive FTIR Method for Measurement of Emissions from Mineral Wool and Wool Fiberglass Industries
Performance Specification 15 for Extractive FTIR CEMS in Stationary Sources
Method 320 Vapor Phase Organic and Inorganic Emissions by FTIR(extractive)
Method 321 for the determination of HCl for Portland Cement Industries
Protocol for Extrative FTIR for Analysis of Gas Emissions

2006-11-09T11:10:00.000-08:00

Air Compliance Testing Now Offers FTIR

Commonly referred to as FTIR, Fourier Transform Infrared Spectroscopy is the most recent addition to the Air Compliance Testing technological toolbox. FTIR can be used to identify chemicals from paints, polymers, coatings, spills, drugs, and contaminants (qualitative analysis). FTIR is likely the most powerful tool for identifying types of chemical bonds (functional groups). The wavelength of light absorbed is characteristic of the chemical bond as can be seen in this annotated spectrum. Because the strength of the absorption is proportional to the concentration, FTIR can also be used for some quantitative analyses.

FTIR Applications include:
- Identifying gas stream organic compounds and many inorganic compounds
- Chemical process monitoring and optimization
- On-line process monitoring
- Measuring moisture in corrosive gases
- Reaction end point determinations
- Measuring catalyst efficiency
- Control equipment optimization
- Real time speciated VOC emission analysis
- Indoor air monitoring of VOC's and semi-volatiles at very low levels
- Blending processes optimization
- Ambient air and employee exposure monitoring

By now you’re probably wondering how FTIR works: Because chemical bonds absorb infrared energy at specific frequencies (or wavelengths), the basic structure of compounds can be determined by the spectral locations of their IR absorptions. The plot of a compound's IR transmission vs. frequency is its "fingerprint" that can be compared to reference spectra to identify the material. FTIR spectrometers offer speed and sensitivity impossible to achieve with older wavelength-dispersive instruments. This capability allows rapid analysis of micro-samples down to the nanogram level is some cases, making the FTIR unmatched as a problem-solving tool in organic analysis.

Fourier transform infrared spectroscopy is preferred over dispersive or filter methods of infrared spectral analysis for several reasons:
- It is non-destructive
- There are few sample constraints; solids, liquids and gases can be accommodated.
- It provides a precise measurement method which requires no external calibration
- Because all of the frequencies are measured simultaneously, most measurements by FT-IR are made in a matter of seconds rather than several minutes.
- It has greater optical throughput
- Mechanical Simplicity: The moving mirror in the interferometer is the only continuously moving part in the instrument. Thus, there is very little possibility of mechanical breakdown.
- Sensitivity is dramatically improved with FTIR. The detectors employed are much more sensitive, the optical throughput is much higher, which results in much lower noise levels, and the fast scans enable the coaddition of several scans in order to reduce the random measurement noise to any desired level.

- These instruments are self-calibrating and never need to be calibrated by the user.

Contact Air Compliance Testing at 1-800-EPA-AIR1 to see how we can apply this incredible diagnostic tool to your process improvement or problem.

More info at http://www.aircomp.com