Subsequently, this system was replaced by built-in retention tanks. These retention tanks utilized wash and galley water for toilet flushing purposes. The system posed several opera-tional problems, including the fact that the flushing water taxed the capacity of the retention tanks on longer flights, and was later replaced by recirculating chemical toilets. Recirculating chemical toilets currently being used aboard commercial aircraft have highly improved features to fulfill the requirements of the modern planes. Reinforced fiber-glass retention tanks for lightness, teflon coated toilet bowls for cleanliness, timer assemblies to control the flush cycle, improved reversible-motor-operated pumps, and a number of filter and filter-cleaning devices have all been developed to provide trouble-free operation and an aesthetic facility. The recirculating chemical toilets provide efficient oper-ation but, depending on the capacity of the water tank, the system requires frequent ground servicing. Furthermore, the amount of space and weight available for waste storage in aircraft is quite limited. Therefore, a system to concentrate the wastes during the flight is considered highly desirable. To achieve this, several waste-volume-reduction techniques have been investigated for use aboard commercial aircraft. These include: 1) Evaporation of the liquid to yield dry or highly concentrated solids to reduce the waste-storage space in the aircraft and eliminate the frequent ground servicing need. 2) Incineration devices which utilize electrical and fuel energy for waste incineration. Several improved incineration systems for aircraft appli-cation have been built and evaluated. 57 – 59 3) Evapo-combustion system to burn the macerated waste into a combustion chamber of the jet en-gine. Vacuum toilets have also been successively installed on large commercial aircraft. These toi-lets reduce the waste accumulation. 34, 60 – 64. RAILROAD TRAINS Historically, wastes from railroad trains have been discharged into the environment without benefit of any treatment. This primitive practice poses a threat to the public health. Although passenger traffic on trains in the US has declined in recent years, large numbers of persons, including railroad employees still use toilet facilities on trains. According to Food and Drug Administration (FDA), about 23 million pounds of human excrement or 16 million gallons of wastewater are discharged annually from locomotives and cabooses, and about 9.5 mil-lion gallons of “untreated human wastes” were discharged in 1968 from intercity and commuter passenger train cars. 56 A history of some of waste disposal practices of Amtrak was presented in a hearing before Congress in 1988. 65 Federal laws and regulations now prohibit buses (42 CFR 72.156) from discharging untreated human waste. 56,57 As a result, the passenger buses are equipped with suitable types of chemical or recirculating toilets. Currently, several types of waste treatment and disposal systems are being marketed which are designed and built for railroad trains. These include incinerating toilets, retention tanks, and recirculating toilets. Incinerating toilets built for railroad cars operate on natural gas, propane, diesel fuel, or electricity. These toilets operate without the use of water or chemicals and require no holding tanks or plumbing fixtures. Recirculating toilets of various types are also available for railroad use. One system built for locomotives, cabooses and crew cars uses a vacuum system. In this system air, rather than water, is used to carry waste from the toilets to a centrally located tank. 56,61 This system enables locating the holding tank elsewhere in the railroad car and two or more toilets can be connected to this tank. PICKUP CAMPERS, TRAVEL-TRAILERS, TENT CAMPING Various types of portable recirculating toilets are currently manufactured. These units have suitcase-style handles molded into their cases for easy carrying; can be used in tents or in camper. 66 A small family can get a few day’s use before the facility must be emptied and recharged. A unique system for reducing the volume of wastes from recirculating toilets was developed. In this system, the fecal wastes were liquefied by adding chemicals. The liquid mixture is pumped to a sanitizer which is a short, stainless steel tank connected to the exhaust pipe of the vehicle. The sanitizer operates at about 500°F. At this operating tempera-ture, the waste is concentrated and the microorganisms are destroyed. 66 The operating temperature of the sanitizer is reached at a vehicle speed of about 35 mph. ENVIRONMENTAL CONTROL AND LIFE SUPPORT SYSTEMS (ECLSS) FOR SPACE STATION NASA has sponsored programs to develop efficient, compact equipment to handle the various aspect of environmental life support for spacecraft and for the planned space station. The tasks include CO 2 removal, O 2 regeneration, temperature and humidity control, the purification of water recovered from the dehumidifier condensate, hygiene uses, and in the future, from urine. Also the removal of trace contaminants from the air, the maintenance of the air composition and pressure, and the storage of solid wastes pending their return to earth are included. A wide variety of techniques have been evaluated depending upon their prospects for meeting the desired per-formance specifications. 67 – 73 Table 1 provides a list of ECLSS technologies used or evaluated. The space systems have grown in complexity and compre-hensiveness as both the duration of the missions and the size of the crew have increased. With the possibility of long dura-tion space missions to other planets, and also the establishment of bases on the moon, NASA is in the early stages of testing technologies for solid waste treatment and recycling, and the C019_002_r03.indd 1090C019_002_r03.indd 1090 11/18/2005 11:06:46 AM11/18/2005 11:06:46 AM
1091intensive agricultural technique necessary to grow and process food in very confined spaces under low or zero gravity. Some of the technologies developed for the space program have possible application on earth. Many of the applications will only be relevant to submarines and hyper-baric chambers. In some cases there may be more widespread uses, such as the recovery and reuse of dehumidification and hygiene water in arid areas or in very cold climates, remov-ing CO 2 and regenerating O 2 , and controlling temperature and humidity in deep mines or while drilling long tunnels. Certain technologies may be applicable to the treatment of industrial emissions and/or effluents. It is likely that the basic technological knowledge will be applied to terrestrial problems, rather than the actual hardware developed for the space program. 74 – 77 Possible terrestrial application of space craft environmental systems are presented in Table 2. TABLE 1ECLSS technologies used or evaluatedECLSS subsystem category Used/Evaluated TechnologyAtmosphere revitalisation Used LiOHUsed Molecular sieveUsed Sabatier reactorUsed Static feed water electrolysisEvaluated Solid amine fixed bedEvaluated Liquid sorbent closed loopEvaluated Bosch systemEvaluated Algal bioreactorEvaluated Growing green plantsTrace contaminant removal Used Activated charcoalUsed Catalytic oxidiserUsed Particulate filtersWater recovery and management Used Vapor compression distillationUsed ChlorineUsed Sodium hypochlorite injectionUsed Iodine injectionUsed Heat sterilisationUsed Fuel cell byproduct waterEvaluated Unibed filterEvaluated TIMES membrane filterEvaluated Reverse osmosisEvaluated ElectrodialysisEvaluated ElectrooxidationEvaluated Supercritical water oxidationEvaluated ElectrodeionisationEvaluated Air evaporationEvaluated Vapor phase catalyticammonia removalEvaluated Immobilised cell or enzyme bioreactorsEvaluated Plant transpiration and water recoveryTemperature and humidity control Used Condensing heat exchangersUsed Water cooled suitsAtmosphere control and supply Used Compressed gas storageUsed Cryogenic gas storageWaste management Used Urine stored in bagsUsed Feces stored in bagsUsed Urine ventedUsed Feces stored in bags and vacuum driedUsed Urine stored in tank and ventedUsed Feces stored in bags and compactedC019_002_r03.indd 1091C019_002_r03.indd 1091 11/18/2005 11:06:47 AM11/18/2005 11:06:47 AM
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A joint NASA and NSF life support system utilizing some of the water recovery, waste treatment, plant growth, and energy efficiency technologies is to be installed at the US research sta-tion at the South Pole. This will provide a real world opportu-nity to use the planned technologies on a realistic scale. 78 REFERENCES 1. Sauter, G. and K. Leonard, Natural Home Remedy, Water Environment & Technology, Water Environment Federation, 7, No. 8, pp. 48–52 (August 1995). 2. US Environmental Protection Agency, Design manual, Onsite waste-water treatment and disposal systems, Office of water Program Opera-tions, Municipal Environmental Research Laboratory, Cincinnati, Ohio, EPA 625/1-800-012, October 1980. 3. US Environmental Protection Agency, Handbook of Septage Treat-ment and Disposal, USEPA 625/6-84-009, Center for Environmental Research Information, Cincinnati, OH, October 1984. 4. Qasim, S.R., Wastewater Treatment Plants: Planning, Design and Operation, Technomic Publishing Co., Lancaster, PA (1994). 5. Manual of septic-tank practice, USPHA, Publication No. 526, US Department of the Interior, Washington D.C. (1967). 6. Coulter, J.B., The septic tank system in suburbia, Pub. Health Rept., 73, 488 (1958). 7. Winneberger, J.H., et al. , Biological aspects of failure of septic tank percolation systems, Final report, Sanitary Engineering Research Labo-ratory, University of California, Berkeley (August 1969). 8. Laak, Rein., Wastewater Engineering Design for Unsewered Areas, Second edition. Technomic Publishing Co. , Lancaster. PA. (1986). 9. Andreadakis, A.D., Organic matter and nitrogen removal by an on-site sewage treatment and disposal system, Water Research (G.B.), 21, 559 (1987). 10. Scalf, M.R. et al., Environmental effects of septic tank systems, US Envi-ronmental Protection Agency, Ada, Oklahoma, EPA-600/3-77-096, 1977. 11. Sharp, W.E. et al., Restoration of Failing On-site Wastewater Disposal Systems Using Water Conservation, Journal Water Pollution Control Federation, 56, No. 7, pp. 858, (July 1985). 12. Reid and Leroy C. Jr., Design of wastewater disposal systems for indi-vidual dwellings, Journal Water Pollution Control Federation, 43, No. 10, pp. 2004–2010 (October 1971). 13. Report on Individual household aerobic sewage treatment systems, National Research Council–National Academy of Science, Publication No. 586 (February 1958). 14. Thomas, H.A. Jr. et al. , Technology and economics of household sewage disposal systems, Journal Water Pollution Control Federation, 32, No. 2, p. 113 (February 1960). 15. U.S. Environmental Protection Agency, Design Manual on Constructed Wetland and Aquatic Plant System for Municipal Wastewater Treatment Plants, Office of Research and Development, Center for Environmental Research Information, Cincinnati, Ohio, (September 1988). 16. U.S. Environmental Protection Agency, Subsurface Flow Constructed Wetland for Wastewater Treatment – A Technology Assessment, Office of Water, EPA 832-R-93-00, (July 1993). 17. U.S. Environmental Protection Agency, Subsurface Flow Constructed Wetlands, Proceedings of the Subsurface flow Constructed Wetlands Conference, August 16 and 17, 1993, University of Texas at EL Paso, (1993). 18. Qasim, S.R., N.L. Drobny, and B.W. Valentine, Process alternatives available in packalaged wastewater treatment plants, Water and Sewage Works, 177, Reference Number, pp. R-99 (November 1970). 19. Mahoney, J.A., Summary of commercial wastewater treatment plants, report No. AD 860 067, Air Force Systems Command, Kirtland Air Force Base, New Mexico, (September 1969). 20. Seymour, G.G., Operation and performance of package treatment plants, Journal Water Pollution Control Federation, 44, No. 2, pp. 274 (February 1972). 21. Defne, R.R., G.E. Elbert, and M.D. Rockwell, Contact stabilization in small package plants, Journal Water Pollution Control Federation, 44, No. 2, p. 255 (February 1972). 22. Sancier, J.W., The application or package wastewater treatment plants to suburban areas, Water and Wastes Engineering, p. 33. (December 1969). 23. Water Pollution Control Federation, Natural Systems for Wastewater Treatment, Manual of Practice F9–16, Water Pollution Control Federa-tion, Washington D.C. (1990). 24. Dinger, R., Natural Systems for Water Pollution Control, Van Nostrand Reinhold Co. New York, (1982). 25. Mellor, M., Utility on Permanent Snowfields, Monograph III-A2d, U.S. Army Corps of Engineers, Cold Regions Research Laboratory, Hanover, NH (1969). 26. An Alaskan Challenge: Nature Village Sanitation, US Department of Housing and Human Services, Y3.T 22/2:2AL 1S, (1994). 27. Alter, A.J., Arctic sanitary engineering, Federal Housing Administra-tion, Washington, DC (1950). 28. Clark and Groff Engineers, Sanitary waste disposal for navy camps in polar regions, final report to Naval Civil Engineering Laboratory on Contract NBy-32205 (1962). 29. A New Device for Cold Region Sanitation Disposal—the Alas-Can, The Northern Engineer, 22, No. 1, (Spring 1990). 30. Product Literature, Lehman Hardware and Appliances, Inc., Kidron, Ohio (1995). 31. Walters and Charles F., Promise disposal system, Water and Sewage Works (August 1962). 32. Walters, Charles F. and J.A. Anderegg, Water conservation through reuse of flushing liquid in an aerobic sewage treatment process, paper presented at 11th Alaska Science Conference (August 20, 1960). 33. Kouric, R., Toilets: Low Flush/No Flush, Garbage: The Practical Jour-nal for the Environment, 2, No. 1, pp. 16–24, (January 1990). 34. Water-wise Toilets, Technology Review, 97, (1994). TABLE 2Possible terrestrial applications of spacecraft environmental systemsECLS systems Possible earthbound usesWater reclamation Submarines, arid area operations, supply of filtered and sterile water for medical, experimental uses. Cleaning industrial effluent.Oxygen generation Submarines, medical use in oxygen enriched atmosphere, hyperbaric chambers, under water habitats and deep undergroundwork locations.CO2 removal Submarines, rescue and scuba equipment, under water habitats, hyperbaric chambers. Cleaning industrial emmissions. Revitalising atmosphere in deep underground work locations.Trace contaminant removal Submarines, under water habitats, hyperbaric chambers.Temperature, humidity control Passive systems developed for the control of the space station temperature gain and loss from and to space itself may have some terrestrial applications. Active systems used in controlling temperature in locations where there are localised sources of heat may be useful for cooling dense electronics, in satellites, possibly in aircraft, and perhaps in advanced super computers.C019_002_r03.indd 1092C019_002_r03.indd 1092 11/18/2005 11:06:47 AM11/18/2005 11:06:47 AM
1093 35. Pollen, M.R. and D.W. Smith, Water Conservation in Borrow Alaska, Proceedings of the Third Symposium on Utilities Delivery in Cold Regions, University of Alberta, Edmonton, Alberta, Canada (1982). 36. Viraraghavan, T. and G. Mathavan, Effect of Low Temperature on Physi-cochemical Processes in Water Quality Control, Journal of Cold Regions Engineering, American Society of Civil Engineers, 2, No. 3, (1988). 37. U.S. Environmental Protection Agency, Water Related Utilities for Small Communities in Alaska, EPA-600/3-76-104, Environmental Research Laboratory, Office of Research and Development. Corrallis, Oregon, (1976). 38. Bowen, P.T. and J.C. Lan, Wastewater Treatment of the South Pole, Water Environment and Technology, 5, No. 3, (March 1993). 39. Federal Water Pollution Control Administration, Wastes from water-craft, US Senate, 90th Congress 1st Session, Document No. 48, US Government Printing Office, Washington, DC (August 7, 1967). 40. The Clean Water Act Amendments of 1981, PL 97–117, Title III, Sec. 311.(b)(1). 41. 33 CFR, Part 159, Marine Sanitation Devices, (1994). 42. Wachinski, A.M. and M. Knofczynski, Managing Shipboard Wastes, Water Environment and Technology, Water Environment Federation, 4, pp. 58–62 (August 1992). 43. Hertzbery, R.H., Waste disposal from watercraft, Journal Water Pollu-tion Control Federation, 40, No. 12, p. 2055 (December 1968). 44. Oertle, Lee, Plan a head, monomatic self-contained recirculating head, Popular Mechanics, p. 140 (December 1968). 45. Manning, A.P., Headspace and horse sense on chlorinator, Motor Boat-ing, pp. 42–47 (March 1968). 46. Dugan, P.R. and F.M. Pfister, Evaluation of marine toilet chlorinator units, New York State Department of Health, Project No. GL-WP-1 (July 1962). 47. Yacht Safety Bureau, Inc., Requirements of marine sewage incinerating devices (February 1968). 48. Stewart, M.J. and H.F. Ludwig, Shipboard extended-aeration waste-water treatment plant design, Naval Engineering Journal, 109, pp. 985 (December 1963). 49. Singerman, H.H. and E.T. Kinney, The Navy’s technological prog-ress in water pollution abatement, Naval Engineers Journal, pp. 795 (October 1968). 50. Bockris, J.O. and Z. Nagy, Electrochemistry for Ecologist, Plenum Press, New York (1974). 51. Qasim, S.R. and N.L. Drobny, Development of a waste treatment system for naval vessels phase I-laboratory studies, research report, Battelle Memorial Institute, Columbus Laboratories (October 1970). 52. Droby, N.L., S.R. Qasim, and A. Cornish, Waste management systems for naval vessels, proceedings of the 17th Annual Meeting and Equip-ment Exposition, Institute of Environmental Sciences, Los Angeles, California (April 1971). 53. Joungs and Jim, et al. , Accessory Guide, Trailer Boats, pp. 70–78, (April 1995). 54. Sanitation manual for land and air conveyance operation in interstate traffic, Public Health Service report, 58, No. 5, pp. 157–193 (January 29, 1943). 55. Handbook on sanitation of airlines, US Department of Health, Educa-tion and Welfare, Public Health Service Publication No. 308, Vol. 31, Washington, DC (1953). 56. Environmental pollution: Discharge of raw human wastes from rail-road trains, 32nd report by the Committee on Government Operations, Washington, DC (October 8, 1970). 57. U.S. Congress, Discharge of Waste on Air and Highway Conveyances, Public Law, 21 CFR, 40 CFR 56524, February 1975, and as amended 48CFR 11432, March 18, 1983. 58. Fredric, E.W. and B. Mangus, Waterless toilet, US Patent 3, 110,037 (C14-131) (November 1963). 59. Krukeberg, C.W. and R.J. Jauch, Assignors to Tokheium corporation, Indiana, Incinerating Toilet, US Patent 2,995,097 (C1 110-9) (August 1961). 60. Duncan, Leon, L., Assignor to William J. King, Palos Park, III., Total disposal unit and method, US Patent, 3, 319,588 (C1 110-9) (May 1967). 61. Watkins, A.M., Sanivac-Revolutionary vacuum toilets, Popular Sci-ence, p. 86 (July 1970). 62. Kourik, R., Toilets: The Low-flush/No Flush Story, Garbage, p. 16, (January/February 1990). 63. Research Products/Blankenship, Incinolet: That Electric Toilet, Research Products/Blankenship (August 1994). 64. Alternative Toilets, National Small Flows Clearing House, US Envi-ronmental Protection Agency, West Virginia University, Morgantown, W.Va. (March 1994). 65. Committee on Government Operations, Government Activities and Transportation Subcommittee, Dumping of Human Waste from Amtrak Trains, Hearing Before a Subcommittee of the Committee on Govern-ment Operation, House of Representatives, 100th Conferee, Second Session, Washington, D.C., September 27, 1988. 66. For the travelling family: Take along comfort station, Popular Science, p. 99 (August 1970). 67. Hightower, T.M., Recycling and Source Reduction for Long Duration space Habitation, Proceedings of the 22nd International Conference on Environmental Systems, Seattle, WA, July 13–16, 1992. Society of Automotive Engineers, Warrendale, PA (1992). 68. Wieland, P.O. Designing for Human Presence in Space: An Introduc-tion to Environmental Control and Life Support Systems. George C. Marshall Space Flight Center, NASA RP-1324 (1994). 69. Ramananathan, R., J.E. Straub, and J.R. Shultz. Water Quality Program Elements for Space Station Freedom, Proceedings of the 21st Inter-national Conference on Environmental Systems, San Francisco, CA, July 15–18, 1991. Society of Automotive Engineers, Warrendale, PA, pp. 1–21 (1991). 70. McElroy, J.F., T.M. Molter, and R.J. Roy, SPE Water Electrolyzers for Closed Environment Life Support, Proceedings of the 21st Inter-national Conference on Environmental Systems, San Francisco, CA, July 15–18, 1991. Society of Automotive Engineers, Warrendale, PA, pp. 261–270. (1991). 71. Howard, S.G. and J.H. Miernik, An Analysis of Urine Pretreatment Methods for Use on Space Station Freedom, Proceedings of the 21st International Conference on Environmental Systems, San Francisco, CA, July 15–18, 1991. Society of Automotive Engineers, Warrendale, PA, pp. 157–166 (1991). 72. Herrman, C.C. and T. Wydeven, Physical/Chemical Closed-loop Water Recycling for Long Duration Missions, Proceedings of the 21st Inter-society Conference on Environmental Systems, Williamsburg, VA, July 9–12, 1990. Society of Automotive Engineers, Warrendale, PA, pp. 233–245(1990). 73. Miernik, J.H., B.H. Shah, and C.F. McGriff. Waste Water Processing Technology for space Station Freedom: Comparative Test Data Analy-sis, Proceedings of the 21st International Conference on Environmental Systems, San Francisco, CA, July 15–18, 1991. Society of Automotive Engineers, Warrendale, PA, pp. 229–239 (1991). 74. Rossier, R.N., Nuclear Powered Submarines and the Space Sta-tion: A Comparison of ECLSS Requirement, Proceedings of the 16th Intersociety Conference on Environmental Systems, San Diego, CA, July 14–16, 1986. Society of Automotive Engineers, Warrendale, PA, pp. 321–329 (1986). 75. Straight, C.L. et al. , The CELSS Antarctic Analog Project: A Valida-tion of ECLSS Methodologies at the South Pole Station, In Proceedings of the 23rd Intersociety Conference on Environmental Systems, Colo-rado Springs, CO, July 12–15, 1993. Society of Automotive Engineers, Warrendale, PA, pp. 1–11 (1991). 76. Sribnik, F., R.C. Augusti, and E.G. Glastris, Life Support System for a Physically Isolated Underground Habitat. In Proceedings of the 20th Intersociety Conference on Environmental Systems, Williamsburg, VA, July 9–12, 1990. Society of Automotive Engineers, Warrendale, PA, pp. 1–11 (1990). 77. Dempster, W.F., Biosphere II, Engineering of Manned Closed Ecologi-cal Systems. Journal of Aerospace Engineering, 4, No. 1, Jan 1991, pp. 23–30. 78. Flynn, M.T., C. Straight, and D. Bubenheim, Development of an Advanced Life Support Testbed at the Amundsen-Scott South Pole Station. Preprint. SYED R. QASIM The University of Texas at Arlington C019_002_r03.indd 1093C019_002_r03.indd 1093 11/18/2005 11:06:47 AM11/18/2005 11:06:47 AM
1094 STACK SAMPLING INTRODUCTION It is frequently necessary to determine the amount, con-centration, or rate of emission of various pollutants in the exhaust streams from industrial or commercial processes. Because this generally involves the sampling and eventual analysis of the gas flowing through a stack into the outside air, it is usually called “stack emission sampling”, or more simply, “stack sampling”. In most cases, it is not possible or practical to collect all of the gases emitted to the outside air over any reasonable time period. Therefore, it is necessary to collect only a frac-tion of the overall gas stream. A representative side stream is isolated from the main flow (usually by removing it from the stack altogether) and processed in some way. The gas stream may be filtered, condensed, bubbled, adsorbed, bottled, or pumped through an automatic analyzer. The equipment used for this purpose is called the sampling train. The end result of this step is usually an assessment of the contents of the stream. Meanwhile, an assessment is made about the other characteristics of the stack gas itself, such as temperature and flow rate. The information from these two assessments is then combined to produce a measure of the emissions from the stack in the desired units, such as pounds per hour, grains/dry standard cubic foot, kg/kg of fuel burned, and so on. Generally, the units are chosen to conform with appli-cable regulations. Of course, the testing must include all of the pollutants that are of interest, under all of the process conditions that are needed. This must also include a wide range of checks and balances, often termed Quality Control (QC) and Quality Assurance (QA) to ensure and measure the reliabil-ity of the results. Most importantly, it all must be based on a well reasoned plan, called a Stack Test Protocol or Quality Assurance Project Plan (QAPP) that is written ahead of time and approved by all interested parties. Finally, these results must be reported in a way that fairly represents what was done, to allow regulators and/or the sources to make informed decisions. A prime criterion for method selection is that the method must produce data useful for the purpose intended. For example, is the detection limit of the method low enough to prove compliance with the emission standard, or is the method able to measure and/or account for cyclonic flow in the stack, or is it able to differentiate between similar chemi-cal species, or is that necessary? These sorts of questions fall into a general category called QA. They can be restated as six data quality parameters: P Precision RepeatabilityA Accuracy Bias, closeness to “correct”R Representativeness Typical of actual stack gasC Comparability Similar to other dataC Completeness Enough informationS Sensitivity Low enough detection levels These so-called PARCCS Parameters are simply ways to ensure that the results of a sampling project will yield useful results. When methods published by EPA are used, the PARCCS parameters have already been determined and are built into the methods. For novel methods, the PARCCS parameters must be determined, at least qualitatively. This is well beyond the scope of this chapter but must be borne in mind should new methodology need to be developed to fit a specific circumstance. This leads to the most important warning concerning stack testing. In all but the most dire emergencies, stack test-ing projects should be planned and carried out by trained, experienced stack testing teams. No one should believe that even a close reading of this chapter would provide sufficient background to plan or perform stack tests. There are four recent advances in the stack testing field that rate special mention. The first is the increasing reliance on external quality assurance, as embodied in audit samples and devices. Several agencies and organiza-tions, particularly the Emissions, Monitoring and Analysis Division in USEPA’s North Carolina facility, are now pro-ducing reliable Performance Evaluation (PE) audit samples that can be obtained for the purpose of checking analytical accuracy at the time of sample analyses. They are avail-able for many parameters, as listed in the specific Test Methods. The second major recent advance in stack testing is the development and proliferation of reliable continuous emis-sion monitoring systems (CEMS). CEMS are generally electronic analyzers that determine and record instantaneous concentrations of given parameters continuously. For example, a CEMS for stack gas opacity, termed a transmissometer, shines a light beam through the stack gas and measures the fraction of light transmitted, taking a reading C019_003_r03.indd 1094C019_003_r03.indd 1094 11/18/2005 11:07:13 AM11/18/2005 11:07:13 AM
1095every few seconds. A CEMS for SO 2 extracts a small sample of stack gas and sends it to a monitor outside the stack for analysis and recording. The CEMS records present an excel-lent picture of the continuing status of compliance of the stack gas, reveal any inconsistencies, failures of control devices, or process upsets, and allow plant operators to act immediately when any anomaly appears. It is likely that more and more CEMS will be required as they become available. CEMS are becoming more available for mercury, particulate matter and ammonia. While detailed discussion of CEMS technology, proce-dures, and operation cannot be presented here, the Performance Specifications for the CEMs currently required by USEPA may be found in Appendix B to 40 CFR Part 60, immediately following the Test Methods. A third major advance in stack testing is the introduc-tion of the 300 series methods found in 40 CFR Part 63 Appendix A. In an effort to measure the hazardous air pollut-ants to demonstrate emission reductions pursuant to MACT requirements, EPA has introduced a number of 300 series methods. Some of these methods are specific for pollutants from specific sources. Method 301, which is undergoing revi-sion in 2005, is a field validation procedure that will enable source owners to validate their own test methods in the absence of a recognized EPA method. The fourth is the rewrite of the manual methods into a standard format. The instrumental methods are being rewrit-ten in 2005, along with some major changes. The following sections of this chapter will deal with the selection of sampling and analytical methods, followed by some general information on protocol and final report preparation. Selection of a Sampling Method The choice of stack sampling methodology is most strongly dependent on the pollutants to be measured. In many cases, similar pollutants can be measured with the same or slightly modified methods, while dissimilar pollutants may require totally different methods. The most obvious categorization of pollutants is based on their physical state: gaseous, liquid, or solid. Gaseous pollutants are generally easier to sample and can be collected using one of a few simple train configurations. Liquid and solid pollutants, usually lumped into a single category called particulates, require a totally different collection concept. The following sections will describe the generalized methods employed for collecting particulate and gaseous stack samples. These are followed by more detailed descrip-tions of methods to be used for specific compounds, or groups of compounds. When the U.S. Environmental Protection Agency (EPA) has designated a method as a Test Method, it is required by EPA and by most states for compliance determi-nations. For convenience, the appropriate EPA designations are indicated. When a Test Method is used in establishing an emission limit and is specified by a regulation that method is called the Reference Method. Particulate Sampling When the pollutant of interest is or is attached to solid par-ticles or liquid droplets at stack conditions, it is necessary to select a method that physically traps the particles. But the first step must be the selection of a side stream that is truly representative of the stack exhaust gases. A representative sample of the stack exhaust gas will look and behave like a small-scale version of the actual exhaust gas. It will contain the same fraction of particulates as the main stream (including the same ratios of large and small particles) and will contain a fair share of material from each part of the stack cross section. (This is necessary because gases flow faster near the center of a stack and slower near the walls due to friction). In addition a representative sample must be taken at a location that is free of unusual flow patterns, such as cyclonic flow (in which a significant component of the flow is not along the axis of the stack) or stratified flow (in which the particulates are bunched along one side of the stack). This is because it is very difficult to figure out the actual aver-age flow rate and particulate rate when the measurements are all skewed by the flow anomalies. In most cases, flow abnormalities are caused by recognizable disturbances, such as bends, fans, expansions, contractions, or shape changes in the duct. These disturbances, whether upstream or down-stream from the sampling location, have the potential for making useful testing very difficult, or even impossible. For that reason, the first criterion for good particulate testing is to find a location that is sufficiently far from flow distur-bances. Extensive testing has shown that a sampling location 8 stack diameters downstream from any disturbance and 2 diameters upstream from any disturbance is sufficiently far. In this measurement, the term stack diameter is used liter-ally for circular stacks. For rectangular stacks, an equivalent stack diameter is calculated. In some cases, it is impossible to find a location in the stack or in any straight duct leading to the stack that satisfies these criteria. It is possible to use a location closer to distur-bances. However, other provisions must be taken to account for the possible inaccuracies introduced by the disturbed flow. All of this is described in detail in Test Method 1. Once a sampling location is selected, it is necessary to collect samples of the gas stream that are representative of the gas flowing by that location. This is achieved by sam-pling for a short time at each of several points across the stack cross-section. In practice, two or more holes, or ports, are cut in the stack wall and a sampling probe inserted. The probe is essentially a hollow tube shaped like a shepherd’s crook with the short end, or nozzle, facing into the gas stream. The gas stream is then pumped by suction from the main stream through the nozzle and probe into the collection part of the sampling train located outside the stack. The probe is held in one spot, aligned into the main stream, for a specified time. It is then moved to another point and held for the same time. This process is repeated along the line between the port and the opposite wall. The process of moving the probe along C019_003_r03.indd 1095C019_003_r03.indd 1095 11/18/2005 11:07:14 AM11/18/2005 11:07:14 AM
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this line is called a traverse, and the individual sampling points termed traverse points. The configuration of the ports and the traverse points is generally chosen according to Test Method 1. Three additional considerations must be addressed in order for the sample to be considered representative. First, the particulate-laden gas stream entering the nozzle must be typical of the stream flowing by it. Second, the makeup of the gas stream leaving the probe and entering the rest of the sampling train must be substantially the same as it was when it entered the nozzle. Third, sampling must be conducted at a time and for sufficient duration to cover any inconsistencies in the pollution emission rate. The first of these conditions may sound like overkill. However, the previous work was to ensure the representa-tiveness of the location. This part concerns the representa-tiveness of the gas collected there. This is ensured by careful design of the nozzle and control o the side stream flow rate. The opening of the nozzle is designed with sharply tapered edges. The nozzle itself is shaped to minimize deposition of particulates on the inside walls as the stream turns 90°. The sampling stream flow rate is extremely important because of the difference in aerodynamics and inertial effects of particles. Very small particles tend to behave like gas mol-ecules and tend to follow gas flow stream lines. For these particles, sample flow rates are not critical. Large particles, however, do not necessarily follow the gas flow streamlines. Instead, their flow is controlled more by their inertia. In other words, they tend to keep going in straight lines. Thus, if the flow rate into the sampling nozzles is different than the local gas flow rate, the gas itself and the fine particles will be skewed, either into or out of the nozzle, depend-ing on the relative rates. The large particles, however, will continue along their straight paths. Those, and only those, in direct line with the nozzle face will enter. This can have a significant effect on the measured particulate concentra-tions, depending on the degrees of error in the nozzle flow rate and on the fraction of particulate mass attributable to the large particles. Sampling at exactly the right flow rate is termed iso-kinetic sampling. Sampling at too great a velocity is called superisokinetic, while sampling at too low a velocity is called subisokinetic. Generally, superisokinetic sampling results in an underestimation of the actual particulate con-centration (termed a low bias), while subisokinetic sam-pling results in an overestimation (high bias). Test Method 5 contains instructions for choosing the appropriate nozzle size and sampling flow rate to ensure isokinetic sampling. Sample flow rate and nozzle size are based on the volume of sample gas that needs to be collected and on the flow rate in the stack gas. The needed sample volume is based on the amount of particulate needed for the physical or chemical analyses to be conducted, and will be discussed in the analysis section. The stack gas flow rate is determined according to procedures described in Test Method 2. The procedure involves the measurement of linear flow rate by means of the relationship between the static and dynamic pressure in the gas stream. The static pressure is the pressure of the gas stream, as measured by a pressure tap perpendicu-lar to the flow. The dynamic pressure is the pressure exerted by the flowing stream and is indicative of the flow velocity. It is measured by a pressure tap facing directly into the flow stream. In practice, a device called an “S-type pitot tube” is used to measure static and dynamic pressure at a single loca-tion. Standard calculations are then used to compute the flow rate. By moving the pitot tube across a stack cross section, the flow rate at each point can be determined. All of this is described in detail in Test Method 2. Next, it is necessary to assure that the sample gas stream does not change substantially between the time it enters the nozzle and leaves the probe for the collection part of the sam-pling train. This is accomplished by ensuring that the construc-tion and operation of the probe do not interfere physically or chemically with the flowing sample stream. The nozzle and probe must be made of materials, such as stainless steel, glass, or teflon, that are smooth and do not react with the stream. In addition, the probe may be heated to ensure that vapors in the stream do not condense on the walls of the probe. A stainless steel nozzle and a glass-lined probe heated to 120 ⫾ 14ºC (248 ⫾ 25ºF) will suffice for most situations. However, spe-cial construction materials and/or probe temperature settings may be required for sampling exhaust streams from certain source types of containing certain contaminants. The appro-priate sections of this chapter should be consulted in detail before any decisions are made. The third and final consideration for ensuring represen-tative particulate sampling is that the sampling is conducted at a time and over a sufficient time period to account for variabilities in the exhaust steam. In general, it is desirable to measure the maximum possible emissions, so as to deter-mine compliance under so-called worst case conditions. This is accomplished by first determining the stage or stages in the plant process mot likely to produce the greatest emis-sion rate. This might require preliminary testing, or it may be specified in the applicable regulations. Once the time for testing is selected, it is necessary to decide the duration of each sample run and the number of runs to be performed. Generally, this is specified in the applicable regulation or in the Test Methods. However, in some cases, it may be necessary to select different sampling periods. The basic reason for sampling for any given time is to account for temporal variability in the emissions. Very few processes produce emission streams that are truly con-stant over more than a few minutes at a time. In most cases, though, an hour or two-hour sampling period will be suf-ficient to smooth out any inherent variation in the exhaust stream. In practical terms, this is accomplished by pumping the sample stream through the filter, solutions, or sorbents for the full sampling period. This effectively averages the collected sample over the entire time period. Of course, it is possible that variations in the emission rate with time could mean that higher concentrations are measured at one point in a traverse, such as near one stack wall, etc. However, in most cases, these variations are not significant. The individual regulations or Test methods usually state the required sampling duration. There are two reasons that C019_003_r03.indd 1096C019_003_r03.indd 1096 11/18/2005 11:07:14 AM11/18/2005 11:07:14 AM
1097the sampling duration might be changed. First, if the source is known to vary over a longer or shorter cycle, such that a different sampling period would be likely to yield more meaningful results. Second, with some state operating per-mits establishing very low emission limits, sampling times are increased to provide adequate quantification limits. At this point, the sample gas stream should be as repre-sentative as can be collected using these methods. However, there is still the inherent variability of the methods them-selves. To account for this, most testing programs include a series of three or more test runs in a single test. Depending on the underlying regulations, the results of the test runs can be used independently or averaged to reach a final emission measurement. Once an appropriate sample gas stream has been extracted from an exhaust stream, it must be collected in some way for subsequent analysis. Most particulate sam-pling trains separate the particulate matter from the rest of the gas stream, saving the particulates and exhausting the particulate-free gas sample stream. This separation can be accomplished physically, chemically, or both. Examples of physical separation are filtration, inertial separation (using a “cyclone”), or condensation. Examples of chemical separa-tion include dissolving into solution, adsorption, or chemical reaction into a solution. One or more of these separation techniques may be appropriate for a given particulate material or under given process and/or stack conditions. The specific technique to be used and the limiting conditions may be found under the specific Test Methods described later in this Section. The essence of each is to ensure that all of the particulate matter flowing through the nozzle and probe is actually collected for subsequent analysis. The following is a brief list of these particulate sampling principles, rearranged in an order that might be followed for an actual test. 1) Select a sampling location far from disturbances. 2) Determine traverse point locations. 3) Select appropriate nozzle, probe, heater, and so on. 4) Determine appropriate time for testing (worst case, etc.) 5) Determine isokinetic sampling rates. 6) Select sample train configuration. 7) Perform test runs. Gaseous Sampling When the pollutant of interest is a gas at ambient pressure, sampling is much easier and more straightforward than for particulate samples. This is because gas streams are almost always well mixed across the stack and are not subject to the internal considerations at the nozzle or in the probe. As a result, there is usually no need to worry about the sample location, traversing the stack cross-section, or isokinetic sam-pling. An exception is the measurement of nitrogen oxides from gas turbines using method 20. This method requires a stratification study. The only real concern is that the probe be constructed of materials that will not react with or adsorb contaminants from the sample stream. Sampling is usually performed by inserting a probe at a convenient location and sampling at the centroid of the cross-section. As with particulate sampling, it is important to measure the gas flow rate in the stack to allow calcula-tions of emission rate. This is done in the same way as for particulate sampling using Test Method 2. Protocol and Final Report Preparation A stack sampling project, like most other investigative work, is not likely to succeed unless it is well planned and documented. The Stack Test Protocol, or Quality Assurance Project Plan, is the means used to document the planning of the project. The more detail that can be included in the protocol, the better the likelihood that the test will suc-ceed the first time. Most EPA Regions and State Agencies have specific protocol formats and require specific types of information. Therefore, the project manager should contact the Agency well before the projected test date to obtain the format and to discuss any special conditions that need to be included, such as audit samples. The final Stack Test Report is just as important as the Protocol. It is the means by which the testing team documents what they did and their results. If the Report does not fairly report what actually happened on the stack, in the laboratory and in the calculations, the entire test might well be wasted. Again, it is advisable for the project manager to contact the regulatory agency well before the test to obtain information of acceptable report formats and special information that might be needed. It is likely, though, that the Agency will require copies of all field data sheets, lab data sheets and print-outs, calculation procedures, examples, and results, diagrams, etc. A fourth advance has been made in the dis-semination of stack testing information through EPA’s elec-tronic bulletin board. The Emission Measurement Technical Information Center (EMTIC) bulletin board is available as part of the Technology Transfer Network Bulletin Board Service (TTNBBS). The EMTIC bulletin board includes promulgated methods, proposed methods, some state test methods, papers on stack analysis, a data base on validated methods for various compounds, etc. It can be used to get answers to specific questions. Access to the TTNBBS is available through the Internet at “http://www.epa.gov//ttn” Stack Test Guidance is available at http://www.epa.gov/Compliance/assistance/air/index.html This his document does not address test methods. However, it does provide a good discussion of regulatory requirements for stack testing, including notifications, time frames, observation by regulatory agencies, and reporting. TEST METHOD DESCRIPTIONS The main body of this chapter includes brief descriptions of selected current U.S. EPA Test Methods. These are the C019_003_r03.indd 1097C019_003_r03.indd 1097 11/18/2005 11:07:14 AM11/18/2005 11:07:14 AM
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TABLE 1 Parameters Test methods ConditionsArsenic 108, 108A−CBeryllium 103, 104 103 ScreeningCarbon Disulfide 15Carbon Monoxide 3, 10Carbon Dioxide 3, 3A, 3B, 3A Instrumental3C, 20Carbonyl Sulfide 15Condensible PM 202Chromium 306, 306A ElectroplatingDioxins 23Dry MolecularWeight 3Excess Air 3Field Validation 301Flow Rate 2 VolumetricFlow Rate 2A Small stacksFlow Rate 2B Gasoline Vapor IncinFlow Rate 2C For small ductsFlow Rate 2D For small ductsFlow Rate 2E Landfill gas productionFluoride (total) 13A, B, 14 AL plantsFugitive Emissions 22Gasoline Vapors 27 Leaks from TanksHalogenated Organic 307 Vapor from solvent cleaningHydrogen Chloride 26Hydrogen Sulfide 11, 15Lead 12 Inorganic(continued)methods approved by U.S. EPA for testing emissions from sources subject to the New Source Performance Standards (NSPS), found in 40 CFR Part 60, and the National Emissions Standards for Hazardous Air Pollutants (NESHAPS), found at 40 CFR Parts 61 and 63. The methods themselves can be found in the appendices to those regulations. The U.S. EPA Test Methods may, of course, be used for purposes other than NSPS or NESHAPS. However, their applicability and validity may be unsure. The same is true for methods developed by the states or by others. Many meth-ods are completely appropriate for a given circumstance for which they have been extensively verified (as have the EPA methods for NSPS and NESHAPS). However, their validity under other circumstances should always be questioned until and unless their performance can be confirmed. The descriptions presented here are valuable for develop-ing general understanding of the equipment and procedures. However, the methods should never be attempted without a thorough reading and understanding of the methods them-selves. Stack Testing is still a very complex process that requires experience if useful results are to be obtained. To assist in the selection of a Test Method, Table 1 lists the parameters that can be measured, along with the appro-priate methods. Test Method 1 Test Method 1 is used to determine representative traverse points for measuring solid or liquid pollutants and/or deter-mine total volumetric flow rate from a stationary source. The procedures described in this method are used to determine the minimum number of points, the location of these points, and whether the chosen points are free from cyclonic flow. The Method contains a rote procedure for choosing point locations that are at the centroids or equal area portions of the stack cross section. This ensures equal weighting of all flows into the average flow rate determination. The minimum number of sampling points is determined from Figure 1. This figure is applicable to both round and rectangular ducts based on the distance from the nearest dis-turbance, bend, exit o other obstruction which might disrupt the flow of gas through the duct. The ducts must be at least C019_003_r03.indd 1098C019_003_r03.indd 1098 11/18/2005 11:07:14 AM11/18/2005 11:07:14 AM
1099 TABLE 1 (continued)Parameters Test methods ConditionsLeaking GasolineTank Organics 27Leaks—Organic 21Mercury 101, 101A, 102, 101A From Incinerators102 In hydrogenMercury 105 In Sewage SludgeMetals 29Moisture 4Nitrogen Oxides 20Nitrogen Oxides 7, 7A−E Different methodsNonmethaneOrganics 25Organics—Leaking 21Organics (gaseous) 18, 25A−B A-B-different analyzersOrganics 25C Landfill gasOrganics 25D Waste samplesOrganics 25E Waste samples Organics 304A−B BiodegradationOrganics 305 Individual organics in wasteOrganics 311 Hazardous air pollutants in paintsOxygen 3, 3A, 3B, 3C, 20 3A instrumentalParticulates 5, A-I A-I Specif Facials, 17 In stack filterPM10201 OR 201A, and 202Polonium-210 IIISampling Site ISulfur Dioxide 6, 6A−C, 8 A—Fossil fuel,B—daily average,C—instrumentalSulfur Compounds 15A, 16, 16A 16A Total Reduced,16—SemicontinuousSulfuric Acid Mist 8Surface Coatings 24, 24A Volatiles, water, density, solidsSurface Tension 306B Chromium electroplatingOrganics (gaseous) 18Traverse Point 1Traverse Points 1A For small ductsVelocity 2, 2A-2HVinyl Chloride 107 In Wastewater,107A resin slurryVinyl Chloride 106Visible Emissions 9, 9-Alt, 303, 9-Alt-Lidar,303A,22 fugitivesVolatile OrganicsCapture Efficiency(VOCs) 204 et al.Wood Heaters 28 Certification and auditingWood Heaters 28A Air to fuel ratioC019_003_r03.indd 1099C019_003_r03.indd 1099 11/18/2005 11:07:14 AM11/18/2005 11:07:14 AM
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12 inches (0.3 m) in diameter or 113 in 2 (0.071 m 2 ) cross-sectional area. Sampling ports must not be within 2 duct diameters downstream or half a diameter upstream from any flow disturbance. Sampling points are then determined by dividing the stack into equal area sections as shown in Figures 2 and 3. A table is provided in the Method which gives the percentage of the stack diameter from the inside wall to each traverse point. For stacks greater than 24 inches in diameter, no point should be closer than 1 inch from the wall; for smaller stacks, no closer than 0.5 inch. Once these criteria are met measurement of the direction of flow is made to insure absence of significant cyclonic flow. The angle of the flow is determined by rotating a Type S pitot tube until a null or zero differential pressure is observed on the manometer. The angle of the pitot tube with the stack is then measured. This procedure is repeated for each sampling point and the average of the absolute values of the angles calculated. If the average angle is greater than 20º, the sampling site is not acceptable and a new site must be chosen, the stack extended, or straightening veins installed. A few unusual cases have been accounted for by the method. If the duct diameter or size is smaller than that required by Method 1, Method 1A can be used. For cases where 2 equivalent stack diameters downstream or a half diameter upstream are not available, a directional velocity probe can be used to determine the absence of cyclonic flow, as described in Method 1. If the average angle is less than 20º, then the sampling site is satisfactory; however a greater number of points must be used. Test Method 2 Test Method 2 is used to determine the average velocity in a duct by measuring the differential pressure across a Type S (Stausscheibe) pitot tube. The Type S pitot tube is preferable to the standard pitot tube when there are particles that could cause plugging of the small holes in the standard pitot tube. Measurement sites for velocity determination are chosen as described in Method 1, that is, required number of sites and absence of cyclonic or swirling flow. The type S and standard pitot tubes are shown in Figure 4. When the Type S pitot tube has been correctly manufactured and installed on a probe as shown in Figure 5, there is no interference and calibration is not necessary. A pitot tube constant of 0.84 is assumed. If the criteria for interferences are not met, the method discusses the necessary calibration procedures. DUCT DIAMETERS DOWNSTREAM FROM FLOW DISTURBANCE* (DISTANCE B)2010203040500.51.01.52.0 2.534567 89102024 OR 25a8 OR 9a1612STACK DIAMETER = 0.30 TO 0.61 m (12-24 in)STACK DIAMETER > 0.61 m (24in)FROM POINT OF ANY TYPE OF DISTURBANCE (BEND, EXPANSION, CONTRACTION, ETC.)aHIGHER NUMBER IS FOR RECTANGULAR STACKS OR DUCTSDUCT DIAMETERS UPSTREAM FROM FLOW DISTURBANCE (DISTANCE A)MINIMUM NUMBER OF TRAVERSE POINTSDISTURBANCEMEASUREMENTSITEDISTURBANCEBAFIGURE 1 Minimum number of traverse points for particulate traverses.C019_003_r03.indd 1100C019_003_r03.indd 1100 11/18/2005 11:07:14 AM11/18/2005 11:07:14 AM
1101 Velocity, as measured with a pitot tube, is proportional to the square root of the differential pressure across the two sides of the pitot tube and the density of the stack gas. Most sampling trains use a combination inclined–vertical manom-eter to measure the velocity head, or ∆p. These manometers usually have 0.01 inch of water subdivisions from 0−1 inch of water. The vertical section has 0.1 inch divisions from 1−10 inches of water. This type of gauge provides sufficient accuracy down to 0.05 inches; below that a more sensitive gauge should be used. The temperature of the gases is usually measured using a type K (Chromel-Alumel) thermocouple mounted on the probe. The absolute pressure is calculated by adding the static pressure in the stack to the barometric pressure. The molecu-lar weight of the stack gases is determined using Methods 3 and 4. Velocity is calculated by the equation below: V s ⫽ K p C p (∆p 0.5 ) avg {T s(avg) /(P s M s )} 0.5 where: K p = Velocity equation constant K 34.97msec(g/g - mole)(mmHg)( K)(mmH O)metricp20.5⫽⎡⎣⎢⎤⎦⎥ K 85.49ftsec(lb/lb - mole)(in.Hg)( R)(in.H O)Engp20.5⫽⎡⎣⎢⎤⎦⎥llish C p ⫽ Pitot tube Coefficient (0.84 for S Type without interferences) ∆p ⫽ pressure difference across the two sides of the pitot tube (velocity head of the stack gas) P s ⫽ Absolute pressure of the stack, mm Hg or in. Hg M s ⫽ Molecular weight of the wet stack gases, g/g mole or lb/lb mole T s ⫽ Absolute stack temperature, ºK (273 + ºC) or ºR (460 + ºF) The average dry volumetric stack flow is: Q sd ⫽ 3,600(1 − B ws )V s A(T std /T s(avg) )(P s /P std ) where: Q sd ⫽ Average stack gas dry volumetric flow rate B ws ⫽ Water vapor in the gas stream from Method 4 or 5 V s ⫽ Average stack gas velocity A ⫽ Cross-sectional area of the stack T std ⫽ Standard absolute temperature 293ºK or 528ºF P std ⫽ Standard absolute pressure 760 mm Hg or 29.92 in. Hg 123456TRAVERSEPOINTDISTANCE,% of diameter1234564.414.629.670.485.495.6FIGURE 2 Example showing circular stack cross section divided into 12 equal areas, with location of traverse points indicated.FIGURE 3 Example showing rectangular stack cross section divided into 12 equal areas, with a tra-verse point at centroid of each area.C019_003_r03.indd 1101C019_003_r03.indd 1101 11/18/2005 11:07:14 AM11/18/2005 11:07:14 AM
1102
SECTION AACURVED ORMITERED JUNCTION90° BENDAADSTATICHOLES(0.1D)IN OUTSIDETUBE ONLYHEMISPHERICAL TIPIMPACT OPENING-INNER TUBE ONLY60 (MIN.)80 (MIN.)MANOMETERStandard pitot tube design specifications.1.90–2.54 CM(0.75–1.0 IN.)7.62 CM (3 IN.)TEMPERATURE SENSORTYPE S PITOT TUBELGAS FLOWFLEXIBLE TUBING6.25 MM (¼ IN.)LEAK-FREECONNECTIONSMANOMETERL = DISTANCE TO FURTHEST SAMPLING POINT PLUS 30 CM (12 IN.)PITOT TUBE - TEMPERATURE SENSOR SPACINGType S pitot tube-manometer assembly.FIGURE 4 Type S pitot tube-manometer assembly.C019_003_r03.indd 1102C019_003_r03.indd 1102 11/18/2005 11:07:15 AM11/18/2005 11:07:15 AM
