NOTE 1 A measuring instrument that can be used alone is a measuring system.
NOTE 2 A measuring instrument may be an indicating measuring instrument or a material measure.
NOTE A measuring system may consist of only one measuring instrument.
EXAMPLES Voltmeter, micrometer, thermometer, electronic balance.
NOTE 1 An indicating measuring instrument may provide a record of its indication.
NOTE 2 An output signal may be presented in visual or acoustic form. It may also be transmitted to one or more other devices.
EXAMPLES Standard weight, volume measure (supplying one or several quantity values, with or without a quantity-value scale), standard electric resistor, line scale (ruler), gauge block, standard signal generator, certified reference material.
NOTE 1 The indication of a material measure is its assigned quantity value.
NOTE 2 A material measure can be a measurement standard.
EXAMPLES Thermocouple, electric current transformer, strain gauge, pH electrode, Bourdon tube, bimetallic strip.
EXAMPLES Sensing coil of a platinum resistance thermometer, rotor of a turbine flow meter, Bourdon tube of a pressure gauge, float of a level-measuring instrument, photocell of a spectrometer, thermotropic liquid crystal which changes colour as a function of temperature.
NOTE In some fields, the term “detector” is used for this concept.
EXAMPLES Halogen leak detector, litmus paper.
NOTE 1 In some fields, the term “detector” is used for the concept of sensor.
NOTE 2 In chemistry, the term “indicator” is frequently used for this concept.
EXAMPLE 1 Electro-acoustic measuring chain comprising a microphone, attenuator, filter, amplifier, and voltmeter.
EXAMPLE 2 Mechanical measuring chain comprising a Bourdon tube, system of levers, two gears, and a mechanical dial.
NOTE 1 Types of adjustment of a measuring system include zero adjustment of a measuring system, offset adjustment, and span adjustment (sometimes called gain adjustment).
NOTE 2 Adjustment of a measuring system should not be confused with calibration, which is a prerequisite for adjustment.
NOTE 3 After an adjustment of a measuring system, the measuring system must usually be recalibrated.
adjustment of a measuring system so that it provides a null indication corresponding to a zero value of a quantity to be measured