Instrumentation

Front 1

Absolute pressure

Back 1

The sum of gauge pressure plus atmospheric pressure.

Front 2

Absolute zero

Back 2

Temperature at which thermal energy is at a minimum and all molecular activity ceases, reported as 0°K or-273°C.

Front 3

Accessible

Back 3

Describing a device or function that can be used or seen by an operator for the purpose of performing control actions.

Front 4

Accuracy

Back 4

Conformity to an indicated, standard, or true value, usually expressed as a percentage deviation (of span, reading, or upper-range value) from the indicated, standard, or true value.

Front 5

Actuator

Back 5

A part of the final control element that converts a signal into a forced action.

Front 6

Alarm

Back 6

A device or function that signals the existence of an abnormal condition by means of audible or visible discrete changes, or both, intended to attract attention.

Front 7

Algorithm

Back 7

A detailed set of instructions executed by the central processing unit (CPU), which is the portion of a computer that decodes the instructions, performs the computations, and keeps order in the execution of programs.

Front 8

Alphanumeric

Back 8

A character set that contains both letters and digits.

Front 9

Ambient compensation

Back 9

The design of an instrument such that changes in ambient temperature do not affect readings of the instrument or compensation for ambient conditions when mounting an instrument.

Front 10

Ambient conditions

Back 10

Conditions around the device that are examined (e.g., pressure, temperature).

Front 11

Ammeter

Back 11

An instrument used to measure current.

Front 12

Ampere

Back 12

A unit used to define the rate of current flow (1 amp = 1 coulomb per second).

Front 13

Amplification

Back 13

The dimensionless ratio of output/input in a device intended by design to have this ratio greater than unity.

Front 14

Amplifier

Back 14

A device whose output by design is an enlarged reproduction of the input signal and is energized from a source other than the input.

Front 15

Amplitude

Back 15

A measurement of the distance from the highest to the lowest excursion of motion; for example, the peak-to-peak swing of an electrical waveform.

Front 16

Amplitude ratio

Back 16

The ratio of the magnitude of a steady-state sinusoidal output with respect to the input.

Front 17

Analog

Back 17

A continuous operation signal.

Front 18

Analog computer

Back 18

A computer operating on continuous variables.

Front 19

Analog output

Back 19

A voltage or current signal that is a continuous function of the measured parameter.

Front 20

Analog simulator

Back 20

An electronic, pneumatic, or mechanical device that solves problems by simulation of the physical system under study using electrical or physical variables to represent the process variables.

Front 21

Analog-to-digital converter (A/D)

Back 21

A device or circuit that outputs a binary number corresponding to an analog signal level at the input.

Front 22

Analyzer

Back 22

An automatically operating, analytical measuring device that monitors a process for one or more chemical compositions or physical properties.

Front 23

Anemometer

Back 23

An instrument for measuring or indicating the velocity of air flow.

Front 24

ANSI

Back 24

American National Standards Institute.

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Archived

Back 25

Placed in an assigned, permanent, accessible storage location for possible future retrieval.

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ASCII

Back 26

American Standard Code for Information Interchange.A seven- or eight-bit code used to represent alphanumeric characters.

Front 27

Assignable

Back 27

A term applied to a feature permitting the channeling (or directing) of a signal from one device to another without the need for switching, patching, or wiring changes.

Front 28

Attenuation

Back 28

A decrease in signal magnitude; the reciprocal of gain.

Front 29

Auto-manual station

Back 29

Synonym for control station.

Front 30

Auto-zero

Back 30

An automatic, internal correction for offsets and/or drift at zero voltage input.

Front 31

Automatic control systems

Back 31

Operable arrangements of one or more automatic controllers along with their associated equipment connected in closed loops with one or more processes.

Front 32

Automatic controller

Back 32

A device or combination of devices that measures the value of the variable, quantity, or condition and operates to correct or limit deviation of this measured value from a selected reference.

Front 33

Automatic reset

Back 33

The integral function on a PID controller that adjusts the proportional bandwidth with respect to the set point to compensate for droop in the circuit (i.e., adjusts a controlled process to a set point after the system stabilizes).

Front 34

Automation

Back 34

The act or method of making a processing or manufacturing system without the necessary operator intervention.