Measurement Uncertainty: pressure_manometer_liquid
GUM-compliant measurement uncertainty budget components and coverage factors for common engineering measurements. Covers Type A (statistical) and Type B (non-statistical) uncertainty sources with standard uncertainties, expanded uncertainties at k=2 (95%), and confidence levels for: length/dimension (caliper, micrometer, CMM, gauge block), mass (analytical balance, platform scale), temperature (Type K thermocouple, Pt100 RTD, IR pyrometer), pressure (Bourdon gauge, electronic transducer, liquid manometer), flow (orifice plate, turbine meter, Coriolis, ultrasonic transit-time), electrical (DMM, power analyzer), force (load cell), and torque (torque wrench). Also includes coverage factor reference rows (k=1/2/3, 68/95/99.7%) and distribution divisors (rectangular, triangular, normal, U-shaped). Per ISO/IEC Guide 98-3:2008 (GUM), NIST TN 1297, ISO/IEC 17025:2017.
| measurement type | uncertainty source | confidence level pct (%) | coverage factor k | distribution | divisor | expanded uncertainty k2 | expanded uncertainty unit | notes | standard uncertainty unit | standard uncertainty value | uncertainty type |
|---|---|---|---|---|---|---|---|---|---|---|---|
| pressure_manometer_liquid | combined_standard_uncertainty | 95 | 2 | normal | 1 | 0.34 | mm_H2O | RSS: sqrt(0.14^2+0.10^2+0.02^2) = 0.174 mm H2O; U95 = 0.34 mm H2O; good for very low pressure differential | mm_H2O | 0.17 | Combined |
| pressure_manometer_liquid | fluid_density | 95 | 2 | normal | 2 | 0.04 | pct_FS | Liquid manometer (water or mercury): density uncertainty from temperature measurement; water density 0.00003 g/cm3 per 0.1C change at 20C; uncertainty 0.02% FS | pct_FS | 0.02 | Type_B |
| pressure_manometer_liquid | repeatability | 95 | 2 | normal | 1 | 0.2 | mm_H2O | Type A: repeatability of reading; typically 0.1-0.2 mm H2O for inclined manometer; better than vertical | mm_H2O | 0.1 | Type_A |
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