When you measure multiple variables (e.g., flow rate, temperature, and pressure) to calculate a result (e.g., turbine efficiency), the individual uncertainties combine. PTC 19.1 provides the method:
(often referred to simply as "PTC 19.1" or the "Test Uncertainty Standard") establishes the definitive methodology for evaluating and expressing uncertainty in test measurements. It serves as the underlying mathematical foundation for almost all other ASME Performance Test Codes (PTCs). The standard guides engineers in calculating the "Uncertainty Interval," which defines the range within which the true value of a measurement is expected to lie. The current active version is ASME PTC 19.1-2018 . asme ptc 191 pdf
ASME PTC 19.1 is a copyrighted document and is not typically available for free download as a legal PDF. You can find the most recent versions (such as the 2018 or 2013 editions) at authorized retailers: When you measure multiple variables (e
But the real gem? The . It’s a spreadsheet from hell where every instrument, every human reader, every tape measure thermal expansion gets an error term. Sum them properly (root-sum-square, not absolute — that’s the rookie mistake), and you get the truth: We are 95% confident that the true value lies within ±2.3% of what we measured. You can find the most recent versions (such
This document provides the definitive methodology for calculating and reporting uncertainty in performance tests (e.g., turbine heat rate, pump efficiency, fan flow). It replaces earlier ANSI/ASME standards and aligns with ISO/IEC Guide 98-3 (GUM), but with engineering-specific simplifications.
You might wonder why you should buy the ASME standard when the is available. Here is the difference:
Below is a comprehensive report detailing the scope, significance, and content of the , along with important information regarding access to the PDF.