28
13) CONTROLS AND LIFE OF A LOAD CELL
13.1 STARTING PERIOD:
During the first months from the cell construction, are discharged the superficial stresses due
to the machining and the stresses included in the cements; they
follow
possible
little
variations of zero and sensitivity.
For laboratory precise tests, it is advisable a control and a calibration after the first 6 months
of life of the cell and, further, every year period.
For industrial applications the changes are insignificant and the recalibration useless.
13.2 CREEP:
On a cell loaded for a long period can appear creep of the metal body, of the cements, of the
plastic backing of the gauges.
This creep is shown as a variation of the measure and, unloading the cell, as a non-return to
zero. The variations are acceptable in industrial applications.
13.3 LIFE OF A CELL FOR USE WITH RISKS OF DAMAGES:
(See Chapter 5). After a maximum period of 5 years the cell must be substituted in use with
risks of damages.
A finished cell cannot be submitted to a complete check-up by ultrasound and
magnetoscopic tests, to discover fatigue deteriorations, microfractures, etc., due to unknown
shocks and vibrations.
This rule is imposed by several safety recommendations
Summary of Contents for 500QD Series
Page 23: ...23 ...
