Metrology Glossary – H

At J.A. King, we strive to educate our team and our customers so we can all make informed decisions and improve quality. Having information at our fingertips is the best way to do that. We have compiled a list of the most common terminology within the precision measurement industry, backed by our experts with years within our industry.

Precision Measurement Glossary of Terms

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Half Duplex

System or circuit which allows signals to move in two directions but not simultaneously

Handbook 44 (H-44)

A national standard which helps scale owners and manufacturers verify scale accuracy


The process by which two electronic devices establish communication and agree on a communication protocol.

Hardness Tester

A device used to determine the hardness of a material. Typically refers to testers designed to test the hardness of metals on Rockwell, Brinell, Knoop, or Vickers scales.


Current or voltages which have frequencies that are integer multiples of the fundamental power frequency; common and sometimes dangerous in nonlinear loads.

Hazardous Locations

Places which are dangerous or carry a high risk for injury


Thermal energy, attributable to molecular activity. Energy can be changed in form (first law of thermodynamics) so energy can be expressed in either mechanical work units (Joules or ergs) or thermal energy units (calories or BTUs).

Heat Gun

A device that generates an excessive amount of heat for testing and repair.

Heat Sealer

The process of creating electrically conductive adhesive bonds between flexible and rigid circuit boards, glass panel displays and flex foils using adhesive pre-printed on a connector foil/flex foil

Heat Transfer (Conduction)

Transfer of heat by contact within the same body or from one body to another. Body can be solid, liquid or gas. In metals, conductance occurs by the movement of valence electrons.

Heat Transfer (Convection) 

Heat transfer by actual motion of the hot material (liquid or gas).

Heat Transfer (Radiation)

Heat transfer via transforming thermal energy into electromagnetic waves that travel through space (air or vacuum). The wave is retransformed into heat upon absorption by receptor.

Heat Treat / Heat Treating

A method of thermal strain relieving T/C or RTD wires that have been cold-worked (stamped, machine-formed, etc). For Platinum RTDs elements after winding, anneal at 1800-2200°F, then air-cool. For thermocouples, anneal for 15 minutes at 900-1000°C, cool slowly at about 500°C, then air-cool. Heat treat in clean dry air or Nitrogen or Argon or (if components are required bright) in cracked ammonia or hydrogen with a very low dew point (-40°C and low impurity content). Before annealing, decrease in TCE or other suitable solvent.

Heating Effect

Temperature increase in electrical distribution equipment caused by an increase in RMS current.

Height Gauge

A measuring device used to measure a vertical distance between two parallel surfaces. More advanced height gauges can take multiple readings and use them to calculate the radius or diameter of a circle, or other calculated measurements.

Hermetically Sealed

Sealed in such a way that no air may enter or leave the structure or container.

Hertz (Hz)

The SI unit of frequency, equal to one cycle per second.

High Pass Filter

A filter which blocks low-frequency signals and allows high-frequency signals to pass.


Hipot is an abbreviation for high potential. Traditionally, hipot is a term given to a class of electrical safety testing instruments used to verify electrical insulation in finished appliances, cables or other wired assemblies, printed circuit boards, electric motors, and transformers.


Meter HOLD is an external input which is used to stop the A/D process and freeze the display. BCD HOLD is an external input used to freeze the BCD output while allowing the A/D process to continue operation.

Hot Plate

A small portable appliance that features one or two electric heating elements or gas burners.


A device used to measure moisture content and relative humidity in the atmosphere


The hysteresis is an error of a sensor or gauge, which is defined as the maximum difference in output at any measurement value within the unit’s specified range when approaching the point first with increasing and then with decreasing the input parameter.


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