An Instrument
manufacture recommendations include
periodic calibration requirements that
may included a nationally recognized
standard like NIST. Electronic sensors
and circuits need verification to be
within manufacture specifications.
Although calibration
certification intervals vary, the
purpose is to have an accurate
instrument and measurement procedure.
Sensors life expectancy should also be
evaluated along with the calibration
record and procedure, Performance may
out last the life expectancy.
Calibration intervals depend on use,
with some instruments needed more
frequent verification than others.