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ISO 3567-2011 pdf free download
ISO 3567-2011 pdf free download.Vacuum gauges Calibration by direct comparison with a reference gauge
Manométres — Etalonnage par comparaison directe avec un man ométre de référence.
— quantity to be determined by the calibration (error of reading, correction factor, sensitivity coefficient, for example, in volts/pascals, etc.);
— the uncertainty of the measurand at the time of calibration determined in accordance with 7.3.
Sometimes, a single measurand as a mean over a larger pressure range can be determined such as the
effective accommodation coefficient of a spinning rotor gauge, Ion gauge constant or ion gauge sensitivity.
73 Measurement uncertainty
The standard uncertainty. u, of the quantity determined by the calibration. e.g. error of reading, correction factor, sensitivity coefficient, shall be calculated in accordance with ISOIIEC Guide 98-3. The following uncertainty contributions can be significant.
a) Uncertainty of base pressure due to inaccuracy of measurement and drift in time.
NOTE For the static method, the drift in time can be estimated from the pressure rise after closing the valve to the pump. For the stationary equilibrium method, the drift in time can be estimated by observing the base pressure before gas admission over 30 mm in the same position of the pump valve as during the first calibration point.
b) Uncertainty of calibration pressure due to non-equal density and velocity distribution of gas molecules at the entrance flange of IJUC and reference gauge(s). If the design criteria of 6.1 to 6.3 are met, the standard uncertainty (relative) of these effects may be estimated to u = 0,3 % for pressures I’cal below 100 Pa and u 0,1 % for pressures p greater than or equal to 100 Pa, even if the design criteria of 6.1 are not met.
NOTE This uncertainty includes non-equal density and velocity distribution of gas molecules due to several effects: specific flow conditions by rarefied gas flow through the vacuum system — Including the effect of a partly closed (and therefore not cylinder-symmetrical to the chamber axis) valve to the pump, see Note to 6.3.5 — temperature gradients and drifts in time. sorption. desorption. outgassing. pumping speed of gauges, and smaU leaks. For the last five of these effects, it is assumed that all is state of the art meaning that all components are cleaned and baked out according to the level of required base pressure, the pumping speed of the gauge is less than 11100 of the effective pumping speed, on the chamber, and leak testing has been performed. Lower uncertainties may be estimated, If the laboratory has carefully evaluated the effects mentioned above (e.g. companng measurements at different ports by changing the gauges, measurement of spatial temperature distribution and temporal temperature drift).
c) Uncertainty of calibration pressure due to drift in time.
NOTE This can be estimated by observing the reading of the reference gauge in a time interval typical of that needed to perform the measurements at a given target pressure.
d) Measurement uncertainty of the reference gauge. In addition to the uncertainty value given in the calibration certificate, the following can also contribute to this uncertainty: long-term instability of the gauge, its resolution scatter, scatter of indicated values, inaccuracy of offset measurement, offset drift, effect of ambient conditions, different temperatures of the calibration chamber at use as the reference standard and when it was calibrated, temperature drift and possible mutual influences of the gauges.ISO 3567-2011 pdf free download.
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