Isokinetic sampling means the velocity of the fluid entering the sampling nozzle matches the velocity of the fluid flowing in the main process pipe.
ASME PTC 19.11, "Steam and Water Sampling, Conditioning, and Analysis in the Power Cycle," mandates methods and hardware for obtaining representative samples of steam and water to prevent corrosion, deposition, and turbine damage in power plants. The standard details requirements for isokinetic sampling nozzles, sample conditioning for pressure and temperature, and online monitoring of chemical parameters like cation conductivity and pH to ensure high-purity water. You can find more information about ASME codes on the American Society of Mechanical Engineers website.
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The "conditioning" part of the title refers to how a 1,000 psi, 500°F sample is safely reduced to atmospheric pressure and 77°F for sensors. The PDF includes specifications for: Asme Ptc 19.11 Pdf
For multi-phase fluids like saturated steam, the standard mandates .
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Measurand: mass flow rate determined from differential pressure across an orifice. Inputs: differential pressure, fluid density (temperature/pressure), orifice coefficient, pipe diameter, manometer calibration. For each input, obtain u(xi), compute sensitivity coefficients from the flow equation, include correlations (e.g., common temperature sensor used for density and viscosity), then combine and report U with k. Isokinetic sampling means the velocity of the fluid
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For an official PDF of ASME PTC 19.11-2008 (R2018), you should use the following authorized channels:
ASME PTC 19.11 is part of a larger series of standards under the , which provides various guidelines on instruments and apparatus for performance testing. Other key parts of this series include: You can find more information about ASME codes
A chilling loop using chilled water cuts the final fraction of heat to lock the sample precisely at 25°C, which is the calibration standard for pH and conductivity meters. 5. Safety Devices
While the full PDF runs over 60 pages, the standard is built around several core components: