Vernier Calipers Calibration

This standard covers vernier gauges with external and internal contact faces from 0 – 48″/0 -1000mm. Metric calipers measure lengths up to a maximum of 1000mm using a main scale and vernier scale graduated to read to 0.02mm. Imperial calipers measure lengths up to a maximum of 48″ using a main scale and vernier scale graduated to read to 0.001″. It may be uneconomical for any company or institution to invest in equipment to the level required in order to calibrate vernier calipers fully in accordance with the standard.

It is highly recommended that an appropriate authority such as a UKAS approved laboratory carries out a full calibration on vernier calipers at least once a year. In between UKAS calibrations at a frequency based on usage vernier gauges should be calibrated in-house. A typical in-house calibration would include a written procedure and an associated calibration record sheet which would contain as a minimum the following listed information:

(a) Serial number

(b) Location

(c) Procedure number

(d) The flatness of external measuring jaws

(e) The parallelism of external measuring jaws

(f) The parallelism of internal measuring jaws

(g) Linearity of the measuring scale

(h) Results

(i) Measurement uncertainty

(j) Sentence if appropriate

(k) Date and calibrators signature

(l) Traceability to National Standards

It is necessary that any person carrying out such calibration work should have received appropriate training and have shown the ability to be confident via a suitable training authority. Training records should be held and maintained.

The following is a layout for a typical in-house calibration for a 0 – 150mm vernier caliper.

Calibration to be carried out in accordance with in-house procedure number …………………..

Information includes:

Serial Number: Make:

Calibration Date: Range:

The vernier caliper was mechanically and visually inspected for mechanical performance, damage, wear and missing parts and the following faults were noted:

UKAS certification would also detail a measurement uncertainty in accordance with the schedule.

Calibrators Signature: ………………………………….

A traceability statement in this section would be required for all items and their relevant certification utilised for the calibration of the vernier caliper.