Physically or electronically changing a measuring system so its readings line up with known values: turning a trimmer, editing calibration constants in firmware, shimming a mechanism or re-spanning a transmitter. Adjustment follows an as-found calibration and must be followed by an as-left calibration to show the outcome. Because it changes the instrument, needless adjustment wipes out the drift history that interval analysis depends on.
It was in tolerance but close to the edge, so we made an adjustment and recorded as-left data.
Some labs adjust only when as-found data exceed a set fraction of tolerance, such as 70 %, to keep a clean drift record.
Also heard as
- adjust
Do not mix it up with
- Calibration: Calibration measures and records; adjustment changes the instrument. A calibration can be done with no adjustment at all.
Related terms
Calibration
Comparing an instrument with a better-known standard and recording how its readings line up with the standard's values.
As found
Calibration data recorded on an instrument as received, before any adjustment or repair is made.
As left
Calibration data recorded after adjustment or repair, showing the condition the instrument returns to service in.
Tweak
Shop slang for making a small adjustment to an instrument to bring its readings back toward nominal.