How to legally obtain the PDF: Purchase from the ASME website (asme.org) or access via institutional subscription (e.g., university, company library).
Summary of the standard: ASME PTC 19.1 covers Measurement Uncertainty for performance test codes, including definitions, calculation methods (e.g., systematic/random uncertainty), and reporting.
Alternative search tip: Search for “ASME PTC 19.1 PDF” on legitimate academic or engineering databases (Google Scholar, IEEE, ASME Digital Collection) — not unauthorized repositories.
ASME PTC 19.1 is not a test code for a specific machine; rather, it is the umbrella standard for measurement uncertainty. It serves as the mathematical and statistical foundation for all other ASME PTC codes.
Ensure accuracy: By following ASME PTC 19.1, instrument manufacturers and users can ensure that their instruments and instrument systems are accurately measuring and controlling process variables.
Improve safety: Performance testing helps to identify potential safety risks associated with instrument failures or inaccuracies, which can lead to accidents or equipment damage.
Optimize process efficiency: By ensuring that instruments and instrument systems are performing accurately, process efficiency can be optimized, leading to cost savings and improved productivity.
These are unpredictable variations that cause data to scatter. PTC 19.1 quantifies this as Random Uncertainty asme ptc 191 pdf
2. Random (Precision) Error
This is the "scatter." If you measure the temperature of a bath ten times, you will likely get ten slightly different readings due to noise, vibration, or human factors. PTC 19.1 uses statistical methods (standard deviation) to quantify this scatter. How to legally obtain the PDF : Purchase
, typically calculated using statistical methods like standard deviation from repeated measurements. Systematic Errors (Bias): ASME PTC 19
A measurement without an uncertainty value is incomplete. Whether you are testing a massive steam turbine or a small pump, you need to know the range within which the true value lies. PTC 19.1 provides a standardized mathematical framework to move from raw data to a "confidence level". 2. Key Concepts in the Standard
3. Weaknesses & Criticisms
Dense & Academic Tone: The writing is highly formal, with heavy reliance on statistical notation. New users may struggle without prior uncertainty analysis training.
Limited Digital Features: The PDF is essentially a scanned/print replica—no hyperlinked cross-references between equations, sections, or appendices. Navigating from a formula back to its variable definition is tedious.
Cost vs. Value: At over $150 (ASME member price) for a single-user PDF, it is expensive for independent engineers or small firms, though reasonable for large utilities or testing companies.
Missing Practical Examples: While good, the examples assume perfect instrument calibration records. Real-world issues (drift, uncalibrated sensors, missing data) are not addressed.
No ISO Alignment Table: PTC 19.1 differs from ISO GUM in some terminology (e.g., “random error” vs. “Type A uncertainty”). A cross-reference table would help global users.
ASME. (2018). Test Uncertainty: Performance Test Codes (ASME PTC 19.1-2018). The American Society of Mechanical Engineers, New York.