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ENCYCLOPEDIA OF ENVIRONMENTAL SCIENCE AND ENGINEERING - STACK SAMPLING

Chồng lấy mẫu GIỚI THIỆU Nó là thường xuyên cần thiết để xác định số lượng, tập trung, hoặc tỷ lệ phát thải các chất ô nhiễm khác nhau trong các dòng thải từ quá trình công nghiệp hoặc thương mại. Bởi vì điều này thường liên quan đến lấy mẫu và phân tích cuối cùng của các khí chảy qua một chồng vào không khí bên ngoài, nó thường được gọi là "chồng phát thải lấy mẫu", hoặc đơn giản hơn, "chồng lấy mẫu". Trong hầu hết các trường hợp, nó không phải là có thể có hoặc thực tế. | STACK SAMPLING INTRODUCTION It is frequently necessary to determine the amount concentration 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 fraction 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 applicable 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 reliability 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 .