The Difference between Sampling and Continuous Monitoring for Stack Testing

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When your company requires stack testing, there are a variety of methods that can be utilized to provide you with the information you need. Understanding the difference between sampling the pollutant concentrations and monitoring them will help you hire the right company, as well as request the procedure that is most appropriate for your company.


Stack sampling refers to the acquisition of a small sample of the pollutant concentrations by a certified company. There are different devices and methods a company can use to obtain the sample they require. Once the pollutant is obtained, it is removed from the gas the sample includes and kept as a concentrate. This ensures accurate testing when the sample is sent to the laboratory for analysis. The reporting from the laboratory can take a while to get back to your company, which should be kept in consideration when you plan the testing and appropriate modifications as required by the results.


The main difference between sampling and monitoring for stack testing is the amount of time the procedures take. Sampling can be done in a relatively short amount of time because only a small amount of the pollutant is required. Monitoring, on the other hand, requires real-time analysis of the pollutants. This requires a longer period of time to monitor the concentrations and requires the use of precise analyzers. There are no samples to send to the laboratory because the analyzers are able to produce reports on the spot. This enables you to obtain the reports almost instantly after your testing.

Choosing a Method

When you are determining whether you need stack sampling or monitoring, you will need to take into consideration the type of results you require. The continuous stack testing that is available for monitoring is limited to a small number of specific gas analyzers. It is necessary to discuss your exact needs with your testing agency to determine if you can benefit from continuous monitoring that allows you to see how the pollutants affect the air over time or if you are better off with samples sent to a laboratory.

Stack testing is an intricate process that requires a variety of factors to be successful. When you hire a company to perform your testing, you will need to determine if you will benefit the most from sampling or continuous monitoring. Your testing agency will best be able to inform you of your choices and which process is the most profitable for your company.

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