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.
- ACCURACY: 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.
- AMBIENT AIR: Often used as a term when referencing oxygen analyzer calibration. Ambient air consists of 20.9% oxygen which can be used as a known SPAN gas value.
- AMBIENT TEMPERATURE: The minimum / maximum temperature of air surrounding the device or equipment. A critical parameter when specifying an analyzer.
- ANALOG:
- A parameter which varies in a continuous, rather than incremental or discrete-step manner.
- CALIBRATE:
- To determine the indication or output of a device with respect to a standard.
- 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.
- EMI / RFI:
- Electromagnetic interference / Radio Frequency Interference.
- EXPANDED SCALE:
- 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.
- EXPLOSION PROOF:
- 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.
- FORM:
- 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%
- GROUND:
- Reference point for an electrical system. Often used to indicate an earth connection or negative side of a DC supply.
- LINEARITY ERROR:
- 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.
- NEMA 4X / IP66 ENCLOSURE:
- A rating standard which defines intended use and degree of environmental protection. Typically associated with analyzers that will be installed outdoors.
- 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.
- RANGE:
- The span of values over which a meter will function without entering overload condition, e.g. 0-100ppm
- REPEATABILITY:
- The ability of an instrument to register the same reading in successive measurements of the same input.
- RESOLUTION:
- 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.
- SENSITIVITY:
- The minimum change in input to which a device can respond.
- SHIELD:
- A protective conductive covering that provides a least resistance path to ground for external interference.
- SPAN CAL ADJUSTMENT:
- The ability to adjust the gain of an instrument so the display value.
- T90 Response Time:
- The time required for a sensor to respond to 90% of its total change resulting from a step input.
- TWO-WIRE TRANSMITTER:
- An instrument configuration in which the signal output and power input share two wires, power is transfer on one wire and returned to a PLC or DCS system via a 4 – 20mA signal on the other wire. In most cases, this signal is non-isolated.
- ZERO CAL ADJUSTMENT:
- The ability to adjust an instrument so that zero output or zero display corresponds to a specific input signal, such as 0V or 4mA.