Issue with the height setting of chimney sampling points
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GB/T 16157-1996 Sampling methods for particulate and gaseous pollutants in exhaust gases from stationary pollution sources specifies that the sampling point should be located at a distance of not less than 6 times the diameter downstream of elbows, valves, and reducers； The HJ/T75-2017 and HJ75-2017 Technical Specifications for Continuous Monitoring of Emissions from Fixed Pollution Sources (SO2, NOX, Particulates) stipulate that sampling points should be located at a distance of not less than 4 times the diameter downstream of elbows, valves, and reducers. Then, which of these specifications should be used to determine the height of the sampling platform on the chimney? If the diameter is 6 times larger, an elevator is required when the platform is over 20 meters in length; with a diameter of 4 times larger, no elevator is needed. I’m not sure which of these two standards should be adopted; please advise me
The two standards have different specifications, but both are advisory standards, not mandatory ones. If I had to choose, I would go with the environmental protection standard HJ 75-2017, as it is more convenient given your actual situation, and it is also the latest standard. It would be better to confirm things with the local environmental protection authorities before starting the construction. Although HJ 75-2017 should not pose any problems, it’s still better to get everything done properly in one go, as redoing work is always a hassle. It’s fine as long as the local environmental authorities approve it; otherwise, if they say no (the possibility is very low, but just in case), it could cause problems.
GB/T falls under general provisions and recommended standards； HJ75-2017 is a special standard and a mandatory standard (2007 was not, but it is the version 17 that is in force now); therefore, the latter takes precedence in terms of validity
HJ 75-2017 Technical Specifications for Continuous Monitoring of Flue Gas Emissions (SO2, NOX, Particulates) from Fixed Pollution Sources is an industry-mandated standard that must be followed.