Also referred to as a vocabulary or definition of terms, we have put together some common terms that come up in reference to our precision O2 sensors. If you run across a term you are not familiar with, contact us.
The quality of closeness to a specified value under stated conditions. Usually expressed as uncertainty – the maximum deviation to be expected between a reading or output and the actual value being measured.
The average temperature of air surrounding the device or equipment.
A parameter which varies in a continuous, rather than incremental or discrete-step manner.
To determine the indication or output of a device with respect to a standard.
Temperature scale where 0° = freezing and 100° = boiling point of water at sea level. Formerly known as Centigrade.
A measure of the display span of a meter. By convention, a full digit can assume any value from 0 through 9, a 1/2 digit will display a 0 or 1 and overrange at 2, a 3/4 digit will display up to 3 and overrange at 4. A meter with a display span of ±3999 counts is a 33/4 digit meter.
An arrangement that expands a specific portion of an overall range to occupy a larger portion of the full-scale length than it normally would.
An enclosure capable of withstanding an explosion of a specified gas or vapor which may occur within it and of preventing the ignition of a specified gas or vapor surrounding the enclosures by sparks, flashes, heat or explosion of the gas vapor within.
A method for specifying relay contact configuration: Form A SPST-NO single pole, single throw, normally open Form B SPST-NC single pole, single throw, normally closed Form C SPDT single pole, double throw Change-Over CO same as SPDT
FULL SCALE VALUE:
The arithmetic sum of the two end-scale values (may not apply to some specialized meters, such as power factor). When zero is not on the scale, the full-scale value is the higher end-scale value. Examples: Scale Full Scale Value 0-10 ppm, 0 – 100ppm, 0 – 500ppm, 0 – 1000ppm, 0 – 2500ppm, 0 – 10000ppm, 0 – 1%, 0 – 5%, 0 – 10%, 0 – 25%
Reference point for an electrical system. Often used to indicate an earth connection or negative side of a DC supply.
The difference in an output or activation point due to rising vs. falling input signals.
The total opposition to electrical flow, including both resistive and reactive elements.
INPUT RESISTANCE (INPUT IMPEDANCE):
DC (or AC) resistance measured across the input terminals with signal leads disconnected.
The basic temperature unit of the thermodynamic scale. 0°C= 273K
A measure of the departure from a straight-line response in the relationship between two quantities, where the change in one quantity is directly proportional to a change in the other quantity. Usually expressed as a maximum percent.
A rating standard from the National Electrical Manufacturers Association which defines intended use and degree of environmental protection.
The non-zero output of a device for zero input.
A reading that exceeds full scale. OVERSHOOT The amount by which a meter or process exceeds the final value during
PPM (PARTS PER MILLION):
A convenient format to express very small numbers, such as temperature coefficients. 100ppm is 0.01%. PPM is also written as “trace” as in trace oxygen.
PSIA (PSI Absolute):
A pressure reading using vacuum as the reference.
PSIG (PSI Gauge):
A pressure reading using ambient air pressure as the reference.
The span of values over which a meter will function without entering overload condition, e.g. 0-100ppm
The ability of an instrument to register the same reading in successive measurements of the same input.
The degree to which nearly equal values of a quantity can be discriminated. In digital meters, the value represented by a one-digit change in the least-significant digit.
RTD (RESISTANCE TEMPERATURE DETECTOR):
A metallic sensor where resistance increases in a predictable manner with increasing temperature.
The minimum change in input to which a device can respond.
A protective conductive covering that provides a least resistance path to ground for external interference.
The ability to adjust the gain of a process or meter so the display span corresponds to a specified signal span.
The change in a parameter produced by a change in temperature. Normally expressed in %/°C or ppm/°C.
A semiconductor material which exhibits a known electrical resistance vs. temperature.
The time required for a sensor to respond to 90% of its total change resulting from a step input.
A signal conditioner in which the signal output and power input share two wires, thus minimizing wiring.
The unit of electromotive force. One volt applied to a resistance of one ohm produces a current of one ampere.
Unit of real (effective) electrical power. W = VA x PF in a sinusoidal circuit.
The ability to adjust a signal conditioner or meter so that zero output or zero display corresponds to a specific input signal, such as 0V or 4mA.