Brannan Calibration Services 2025 - Flipbook - Page 19
sales@brannan.co.uk
+44 (0)1946 816600
Frequently asked questions
brannan.co.uk
How often should my instrument be calibrated?
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We recommend getting your instrument calibrated yearly, however the calibration frequency for a speci昀椀c instrument
is up to the individual customer. It should be based on:
- The environment in which the instrument is used,
- The frequency of use,
- Any evidence of changes or trends in calibration data and the level of con昀椀dence required in the readings.
The customer must decide what is the consequence of an incorrect reading?
- If you waste a batch of wine due to an incorrect temperature reading, the consequences are probably far less
than if you are performing a scienti昀椀c experiment to formulate a new drug.
Has the device been subjected to any misuse or obvious damage? If the thermometer is used out on site it is
perhaps more likely to become damaged or knocked than if were kept in a cupboard in the laboratory between use.
How many calibration points should I choose and what speci昀椀c points?
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Calibration points can be drawn on a graph and joined together to form a calibration curve. This therefore allows
the user to estimate the corrections at points where a calibration value has not been measured.
- More calibration points will reduce estimation errors, but each calibration point chosen will incur a cost, so the
number chosen will be a trade-o昀昀 between accuracy and cost.
It is preferable for the customer to consider what points the calibration should be carried out at and specify these
at the time of request. Calibration points should either be:
- Speci昀椀c to your process, such as -18°C, 0°C and 4°C for fridges and freezers
- Or cover a minimum of 80% of the range of instrument if it is for general purpose use.
For example a -10°C to 110°C thermometer can easily be calibrated at 0°C, 50°C and 100°C.
The number of points checked will again be determined by the intended application. If the thermometer is used to
check a single point (e.g. 10°C), then only that point need be checked. However, it may be preferred to select a
small range around a point (e.g. 9°, 10° & 11°C).
Our standard calibrations o昀昀er a 5 point calibration across a minimum of 80% of the instruments range.
What is uncertainty of measurement on my UKAS calibration certi昀椀cate?
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UKAS accreditation requires that estimates of the maximum errors during the calibration are displayed on the
certi昀椀cate.
Uncertainty of measurement is the doubt that exists from the result of the calibration. People assume that well
made instruments should be trustworthy and give correct answers, but for every measurement there is always
a margin of error.
The uncertainty of measurement on our UKAS calibration certi昀椀cates arises from many di昀昀erent factors such as
uncertainties with our calibration equipment, materials used, and environmental conditions.
UKAS certi昀椀cates state the maximum probable uncertainty associated with all aspects of a calibration with a
con昀椀dence level of 95%. These uncertainties are quoted on UKAS certi昀椀cates and can be used as part of the
uncertainty budget for your measuring system.
Do you o昀昀er NIST calibrations?
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Through the International Laboratory Accreditation Cooperation (ILAC) agreement our UKAS accredited calibrations
are to the same international standard that NIST calibrations are performed. Although we cannot issue a NIST
calibration certi昀椀cate our UKAS certi昀椀cates are to the same standard, only using the UK alternative.
The ILAC agreement ensures our UKAS calibration certi昀椀cates are recognised around the world.
Measurement for life.
