TB 9-6665-285-15
(b)
Supply freshly tested batteries, when required.
(c)
Allow time for instrument warm-up.
(d)
Verify instrument battery test(s).
(e)
Zero indicating needle.
(2) Perform calibration operations.
(a) ACTIVE-type instruments.
1. Always record or take note of readings before making any adjustments.
2. Gamma and X-ray RADIAC instrument tolerance of each calibration point is
10 percent of standard's calculated value. This estimated measurement uncertainty (2
standard deviations) is derived by combining uncertainty in standard (source) calibration,
uncertainty in the location of the effective center of the detector, uncertainty contributed by
radiation scatter, and statistical fluctuations in instrument readings. Other parameter
RADIAC instruments; e.g., alpha, should be similarly calibrated when possible.
3. RADIAC instrument adjustment is required only when out-of-tolerance
conditions exist.
4. Guidance on calibration points: Survey meter scales.
aa. Linear scales. Provide a minimum of two calibration points per scale,
separated by not less than 50 percent of full scale for gamma and X-ray RADIAC
instruments. Other parameter RADIAC instruments should be similarly calibrated when
possible. It is preferred that the highest calibration point be taken at 75 to 80 percent of
full scale and the lowest point be 20 to 30 percent.
bb. Logarithmic scales. Meters having a multidecade logarithmic scale shall be
calibrated at two points on one decade and no less than one point on each of the remaining
decades. The points on the "two-point decade" should lie at approximately 75 to 80 percent
and at 20 to 30 percent of the decade.
cc. Digital displays. Meters having an automatic ranging digital display device
for indicating rates shall be calibrated at no less than two points on one decade and at no
less than one point on each of the remaining decades. The points on the "two-point decade"
should lie approximately 75 to 80 percent and at 20 to 30 percent of the decade.
5. Perform calibration requested. Provide a calibration report (examples, for
guidance only, provided at figures 1 and 2) on all ACTIVE-type RADIAC instruments. A
copy of this report will be retained for 5 years following calibration. Questions concerning
the calibration should be resolved by telephone with the individual user in order to
minimize turnaround time.
aa. The calibration report should include the type of calibration service (isotope
or effective energy), calibration geometry, check source geometry and reading (if
applicable), and clear indication of calibration points and RADIAC instrument readings at
those points.
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