Frequently Asked Questions (FAQ)

Frequently Asked Questions

Please check our Frequently Asked Questions to know more about our products and services.

What is a Process Monitor?

Process monitors condition the electrical signals that is generated from a process sensor. Then, it scales the resulting data into a display device, according to the desired unit of measure.

What is a Flow Batch Controller?

Flow Batch Controllers dispense a desired amount of fluid into a container, tank or vehicles. They work in conjunction with a flow sensor and control valve. Option: temperature may be used to estimate fluid density for stored fluids.

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Glossary of Terms

ABSOLUTE PRESSURE — Absolute pressure measurement is relative to the absolute zero pressure. The absolute pressure reading is obtained by measuring the differential pressure force between it and the process side of a sensor.

ACCURACY RATING — A defined limit that measurement errors will not exceed under specific reference operating conditions. The rating includes the combined effects of conformity, hysteresis, dead band and repeatability errors.

CALIBRATION CYCLE — The process of adjusting an instrument or compiling a deviation chart so that its reading can be correlated to the actual values being measured.

CALIBRATION TRACEABILITY — How the calibration process relates comparatively to the calibration steps performed by a national standardizing laboratory, such as NIST.

DAMPING — Oscillation suppression. The viscosity of a fluid is used in viscous damping, while the induced current in electrical conductors is used to affect magnetic damping.

FORCE BALANCE DEVICES (vs motion balance devices) — Instruments which operate by force-balance (between the detected variable and the generated output), require no motion and therefore tend to be more maintenance-free than motion-balance devices.

ERROR, RANDOM — The amount of error that remains even after calibrating a sensor. It is also called precision, while repeatability is defined as twice that, the diameter instead of the radius of the circle within which the readings fall.

HYSTERESIS — Property of an element or sensor that defines whether its output is dependent not only on the value of the input, but on the direction of the current traverse. (The reading of the same value differs as a function of whether the measurement is rising or falling.)

REPEATABILITY — Maximum difference between output readings when the same input is applied consecutively. This is the closeness of the agreement among consecutive measurements of the output for the “same value of the input” under the same operating conditions and approaching from the same direction. It is usually measured as non- repeatability and expressed as in percent of span.

REPRODUCIBILITY —- Closeness of agreement among repeated measurements of the output for the same value of the input made under the same operating conditions over a period of time, approaching from both directions. It includes hysteresis, dead band, drift and repeatability.

VISCOSITY — is a principle parameter in any flow measurement of fluids that describes the internal friction of a fluid or gas. Note: Viscous liquids can cause large errors in flow measurement, thus the appropriate meter must be selected very carefully.

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Resource Standards

NIST Logo
National Institute of Standards and Technology
Gaithersburg, MD
www.nist.gov

American National Standards Institute (ANSI)
New York, NY
web.ansi.org

Underwriters Laboratories
Northbrook, IL
www.ul.com

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