1-5
Q-5. What calibration label is used when actual measurement values must be known to use the test
equipment?
Special Calibration Labels
Two SPECIAL CALIBRATION labels are shown in view C of figure 1-1 that have black lettering
and a yellow background; the size and content of the labels are different. A SPECIAL CALIBRATION
tag (figure 1-1, view C) is used with the smaller of the two labels. These labels or tag are used when some
unusual or special condition in the calibration should be drawn to your attention.
Such special conditions may be deviations from usual calibration tolerances, multiple calibration
intervals, or a requirement for in-place calibration. The special condition that resulted in the SPECIAL
CALIBRATION label should be described on the large label when sufficient space is available on the
instrument or on the tag when the small label is used. Brief descriptions of special conditions are provided
in the following paragraphs.
Q-6. An instrument that must be calibrated in place requires what type of calibration label?
In cases where you do not require full instrument capability, the calibration can be performed with
reduced tolerances or cover less than all ranges and parameters. This approach is often used when the
instrument does not meet full calibration tolerances on certain ranges or parameters, but can still meet
user requirements. On the other hand, the special calibration may be for higher accuracy than usual on a
short-term basis upon your specific request.
MULTIPLE CALIBRATION INTERVALS.—Some instruments have components that require
calibration less frequently than the rest of the instrument. For example, the attenuator in a signal generator
may require calibration every 12 months, whereas the rest of the instrument parameters should be
calibrated every 4 months. Since the attenuator calibration is time consuming and may require unavailable
standards, use of the multiple-interval approach can save considerable time (man-hours) as well as permit
the more frequent calibration to be performed at a lower level laboratory.
When a specific instrument has been designed for multiple calibration intervals, such information is
provided in the applicable calibration procedure. The SPECIAL CALIBRATION label or tag is annotated
with the words MULTIPLE INTERVAL, and the type of calibration performed is indicated; for example,
partial 1 of 2, 2 of 2, complete calibration, and so forth. The calibration due date reflects the due date of
the next partial or complete calibration.
CALIBRATION IN-PLACE.—Some instruments should be calibrated in-place. Annotation on the
SPECIAL CALIBRATION label or tag will alert both you and the calibrator that the instrument should
not be removed, but should be calibrated in-place.
User Calibration Label
Some test and measuring equipment (T&ME) should be calibrated by you instead of your referring
the instrument to a calibration facility. For example, some instruments, such as hardness testers and
densitometers, are provided with their own standards and should be calibrated each time used, or at least
very frequently. Some instruments, such as oscillographic recorders, may require calibration before,
during, and after each use.
Other automatic test equipment (ATE) have self-calibration tests that should be performed each time
used or each day of use. Still other instruments are calibrated as part of checkout procedures performed
daily or weekly and recorded in maintenance logs. Whenever recognized, the requirement for calibration
