Terms Glossary


Acoustics: The degree of sound emitted from the transducer.

Acre Foot: One acre foot equals 43,560 cubic feet or 325,900 gallons.

Alphanumeric: A character set that contains both letters and digits.

Alternating: Two pump control logic to equalize the number of operating hours between two pumps by alternating each cycle of operation.

Ambient: The average process conditions around the device.

Analog Output: A current signal that is a function of the measurement.

ANSI: American National Standards Institute.

AWG: American Wire Gauge.


Backup: A redundant safety system that is used when the primary device malfunctions.

Beam Angle: The area of acoustic pulse transmission that spreads with distance over range.

Bulk Storage: Chemical, water and waste bulk storage tanks sized from 1K-10K gallons.


Celsius: Temperature scale defined by 0°C at the ice point and 100°C at the boiling point of water.

Chemical Compatibility: Reaction of plastic, metal or elastomers corrosive material.

Condensate: Condensed material resulting in water or ice based on temperature.

Conductance: The measure of the ability of a liquid or solid to carry an electrical current.

Controller: A device that takes sensor inputs and automates processes via relays.

CSA: Canadian Standards Association.

Cubic Foot: One cubic foot equals 7.48 gallons or 62.4 pounds of water.

Cubic Foot/Second: A flow rate of 450 gallons per minute or 646,320 gallons per day.

Current: The rate of flow of electricity (1 Ampere = 1 Coulomb per second).


Day Tanks: Chemical, water and waste day storage tanks sized from 0.25K-2K gallons.

Direct Current: An electric current flowing in one direction that is constant in value.

Dead Band: The air gap distance in front of the transducer that cannot be measured by the sensor.

Decibel: Unit of measurement (dB) commonly used to measure the strength of an acoustic signal.

Dielectric Constant: Attraction between two opposite charges separated by uniform medium.

DIN: Deutsches Institut für Normung e.V. The German Institute for Standardization.

Drums: Typically 55 gallon drums are used in chemical feed applications.

Duplexing: A combination of both Lead/Lag and Alternating operations. The primary operation is alternating. However, when a secondary start level is reached, the non-active pump will start to assist in a lead-lag operation.


EMI: Electromagnetic interference.

Excitation: External voltage and current applied to a transmitter during operation.

Explosion Proof: A device that can withstand an explosion of gases within it and prevent the explosion of gases surrounding it due to sparks, flashes or the explosion of the container itself, and maintain an external temperature that will not ignite the surrounding gases.


Factory Reset: Procedure that resets the device back to the factory default settings.

Fahrenheit: Temperature scale defined by 32° at the ice point and 212° at the boiling point of water.

FEP: A derivative of Teflon® that is highly resistant to aggressive media.

FET: A field effect transistor is a solid-state switching device that completes or interrupts a circuit electrically with no moving parts.

FM: Factory Mutual.

FRP: A term used to describe fiberglass reinforced plastic lined tanks.


HART: Highway Addressable Remote Transmitter.

Hertz: Units in which frequency (Hz) is expressed that is synonymous with cycles per second.

Hysteresis: The maximum difference between two set points typically associated with control.


IBC: Intermediate bulk container typically used to transport chemicals on flat bed trucks.

Invert: Term used when the measurement span is reversed from 4-20 mA or 20-4 mA.

Impedance: The total resistive and reactive opposition to electrical flow.

Intrinsically Safe: A device that cannot produce any spark or thermal effects under normal or abnormal conditions that would ignite a specified gas and/or dust mixture.

ISA: International Society of Automation.

ISO: International Standards Organization.


Latch: Control term indicating that in order for a switch to energize or de-energize, both set points must be wet, or both set points musts be dry.

Lead/Lag: Two pump control logic where the primary lead pump activates to empty a sump at the start level and deactivates at the stop level. A secondary lag pump will activate if the primary pump cannot complete the empty operation. The secondary pump will also deactivate at the stop level.

Loop Power: Analog circuit where the device power and signal are delivered on the same two wires.

Loop Resistance: The total resistance of all devices connected in series on a 4-20 mA loop.


Milliamp: One thousandth of an Ampere.

Multi-meter: An instrument used to measure voltage and current.


NEC: National Electric Code. Published by the National Fire Protection Association.

NEMA: National Electrical Manufacturers Association.

NPT: National Pipe Thread.


OEM: Original Equipment Manufacturer.

Offset: Typically refers to the 4 mA span set point.

OSHA: Occupational Safety and Health Administration.


PFA: A derivative of Teflon® that is highly resistant to aggressive media.

PLC: Programmable Logic Controller.

Probe: A generic term that is used to describe many types of sensors.

PMeter: A panel or field mounted display that accepts 4-20 mA sensors inputs.

ProfiBus: An industrial FieldBus network communications protocol originally developed in Germany.


Range: The upper and lower limit values over which the device is specified to function.

Relay: An electromechanical device that completes or interrupts a circuit by physically moving electrical contacts.

Resolution: The smallest change in input, which produces a detectable change in the output signal.

RFI: Radio frequency interference.

RoHS: Compliance with the Restriction of Hazardous Substances Directive. The directive restricts the use of hazardous materials in the manufacture of electronic equipment.


Span: The difference between the limits of the measurement range from zero to full scale.

Specific Gravity: The ratio of material mass to the mass of the same volume of pure water at 4°C.

Sumps: Sumps typically store waste for a short period of time prior to transfer into treatment.


Time Delay: A device the delays a control response by a period of time.

Transmitter: A sensor that has a two or three wire 4-20 mA signal output.

Triac: A solid-state switching device used to control alternating current circuits.

Twisted Pair: Two insulated wires, usually made from copper that are twisted in a regular, six turns per inch spiral pattern used to connect transmitters.


Vacuum: Any pressure less than atmospheric pressure.

Viscosity: The inherent resistance of a substance to flow.

Voltage: An electrical potential which is measured in volts.

Volt-Amp: Unit of electrical measurement that is nearly equivalent to a Watt (identical in DC circuits or when powering devices that absorb all the energy in AC circuits such as incandescent light bulbs). The VA generally refers to a power rating of an AC power supply (stating its power capability) or an AC powered device (stating its power requirements). Typically, in most AC powered circuits, the actual power (Watt) rating will be 60-70% of the Volt-Amp rating (this is due to a number of variables that effect the circuit’s phase angle).