The time for preloading at the highest value and the time between two preloadings should be
at least 30 seconds. After preloading and after steady-state conditions have been reached –
and the calibration item permitting -, the indication of the calibration item is set to zero. The
zero reading is carried out immediately afterwards. For the pressure step variation in a measurement
series, the time between two successive load steps should be the same and not be
shorter than 30 seconds and the reading should be made 30 seconds after the start of the
pressure change at the earliest. Especially Bourdon tube pressure gauges have to be slightly
tapped to minimize any frictional effect of the pointer system. The measurement value for the
upper limit of the calibration range is to be recorded prior to and after the waiting time. The
zero reading at the end of a measurement series is made 30 seconds after complete relief at
the earliest.