Glossary of Thermal Testing Terms



Abbreviation of Antilock Brake System. ABS is a device that reduces the slipping that may occur due to wheels locking up during sudden braking or on low-friction roads. Also called anti-lock braking system. It is necessary to operate this system correctly for it to be able to protect the human body. Many of our in-line type temperature inspection devices have been used in this reliability test.

Absolute Temperature (Kelvin)

Absolute temperature (or Kelvin) is the temperature scale in the same graduations as Celsius, but at which absolute 0 is the point at which the movement of elemental particles would be considered to be thermodynamically stopped. (The lowest theoretical temperature.)The freezing point of water in terms of absolute temperature is 273 K (Kelvin).

Absolute Zero

On the Celsius scale, –273.15 °C. The lower limit of temperature of a substance.

Aging Test

A test in which operation of a device to be inspected is confirmed after a constant current load is left on it at a constant temperature for a long period of time.

Air Chamber Thermal Shock Test

Thermal shock test using air as a medium. Hot air and cold air are sent alternately to the test area to induce thermal shock.

Aspect Ratio

The ratio of width to length. Mainly it specifies the ratio of the long side to the short side of a duct outlet, intake grille frame, or rectangular duct frame.


Background Noise

When a specific sound is considered as a target in a certain place, noise at the place when there is no target sound is referred to as background noise with respect to the target sound. When examining the noise of air conditioning equipment in facilities such as halls and studios, it refers noise when the air conditioning equipment is stopped in the absence of people. Special background noise is noise that enters from the outside, internally generated noise other than air conditioning equipment, and the like. Displayed in dB (A).

Bell Mouth

The point where the speed of the gas or liquid is increased by rapidly squeezing the fluid is called a bell mouth. The bell mouth is the intake port of an axial blower.

Bench Test

A virtual environment to verify that a design is accurate and valid. Although it is smaller than a pilot plant test and is performed on a laboratory scale, it refers to the "environment" for verifying the operation of a circuit such as an LSI (large-scale integrated circuit) in the semiconductor industry. Also, in the automobile industry, it is called an engine vent test, which refers to starting only the engine and performing durability and performance tests to measure exhaust efficiency, fuel consumption, vibration, etc.


One kind of surface mount IC chip, and an IC packaging method using resin, ceramic or metal. Since a grid of small ball-shaped electrodes are lined up on a flat package, there are no protruding electrodes (pins) around the package, giving the advantage of a reduced mounting area.

Burn-in Test

The burn-in test is a method of reducing initial failures by applying temperature and voltage loads in advance. It is one of the most effective screening tests for early failure detection.


Cable Access Hole

Hole for passing measurement cables, etc.

Celsius Temperature

A widely used unit of temperature. The temperature between water's freezing point of 0 °C and its boiling point of 100 °C which is divided into 100 equal parts.

Ceramic Substrate

A substrate made of a ceramic. The ceramic material mainly contains alumina. It is mainly used in SHF and UHF band power circuits due to its excellent high frequency characteristics and thermal conductivity.


A testing chamber. Within the air conditioning industry, it refers to an air chamber used with an air conditioning duct, and is installed for the purpose of absorbing noise, or combining or diverting off air, etc. In the semiconductor industry, it refers to a sealed reaction vessel used to enable a chemical or physical reaction.


A room where air cleanliness is maintained at a specified level.

Climate Chamber

A room where any type of weather condition can be reproduced.

Coefficient of Thermal Expansion

The rate at which the length and volume of an object expands due to a rise in temperature, per 1 K (°C).Expressed in units of 1/K.

Combustion Test

A test in which the test piece is brought close to a flame, then put into the flame, and finally released, and then examined for the presence or absence of softening during that time, the nature of the flame, the difficulty of burning, the presence or absence of self-extinguishing, the burning speed, odor, etc.

Composite Vibration Testing

The composite vibration test is a test for evaluating the resistance to temperature, humidity and vibration stress that a product may undergo during the transportation and use in its operating environment. With regard to various automotive related units and products, there is a demand for durability tests in complex environments where vibration is applied in addition to temperature and humidity.

Compression Test

A test that examines mechanical properties and deformation resistance by applying a compressive load to a specimen and measuring the resulting stress and strain. Brittle materials such as wood, concrete and cast iron are tested until they break and their compressive strength is measured.


The amount of water vapor that can be contained in air is higher as the temperature is higher and lower as the temperature is lower, and if air containing water vapor touches a cold ceiling, floor, wall surface or interior glass surface, piping, ducts, etc., the temperature drops below the dew point of the humid air at that location, part of the water vapor will condense into a liquid (water droplet).The case where water droplets are generated on the surface is called surface condensation, and the case where water droplets are generated inside something is called internal condensation.

Constant Temperature, Constant Humidity Chamber

Also known as a temperature humidity (test) chamber. Test equipment that has partitioned spaces (sample areas) where samples to be tested can be placed and subjected to predefined temperature and humidity.

Constant Temperature, Constant Humidity Chamber

Test equipment that can maintain constant temperature and humidity for extended periods of time regardless of external temperature and humidity conditions and can also perform temperature and humidity cycling testing.

Constant Temperature Device

A device that maintain a constant temperature. Usually such a device is used to maintain a constant air temperature, but also included are devices used to maintain a constant water temperature. In the latter case, they are sometimes also referred to as thermostatic chambers.

Constant Value Control

A control that maintains temperature or temperature/humidity at a constant target value.


A device that converts AC power to DC power. An inverter is a device that rectifies alternating current into direct current and then convert that direct current power into alternating current of an arbitrary alternating frequency. A rectifier circuit for converting AC power to DC is called a converter.

Cooling Tower

A device that cools by sourcing circulating water in the condenser part of the refrigeration unit.

Cross Flow Fan

A kind of fan. A fan with a relatively small diameter but long sideways, often used in air conditioners.


Even among types of quartz, those which are colorless and clear are known called "crystal".Crystal is representative as a piezoelectric material, which means when pressure is applied to it, electricity is formed. At present, piezoelectricity from crystals are mostly used as crystal oscillators, and when used in watches, are simply referred to as "quartz" because watches using quartz oscillators are most common.

Crystal Oscillator

Crystal exhibits a piezoelectric conversion effect in which a voltage is generated when pressure is applied, and a distortion is generated when a voltage is applied, and they are naturally very stable mechanical vibrators. Electrode plates are attached to a cut piece of crystal, and if a voltage is applied at the characteristic vibration frequency as determined by the type, shape, size, etc. of the piece of crystal, it will operate as a stable tuned circuit. A crystal oscillator is an oscillation circuit in which a crystal resonator is placed in the feedback path of an amplifier, and can obtain oscillation characteristics with excellent temperature characteristics of 10¯⁶ to 10¯¹⁰ / °C at a frequency of several kHz to several tens of MHz.

Crystal Resonator

This is an electronic component that resonates when an AC voltage is applied to a piece of crystal, and it can oscillate at a highly precise frequency. This is the general term for piezoelectric vibrators that operate using the piezoelectric phenomenon of crystal. Sheets cut from a single crystal at a specific angle with respect to the crystal axis have various shapes, but when an AC voltage is applied to both surfaces, the oscillating current can be converted into mechanical vibration, and vice versa.

Current Rating

A value indicating the effective maximum AC current that can be continuously output by an inverter; current exceeding this value must never be continuously supplied.


Modifying a product according to a customer's order specifications.



The active removal of frost sticking to something.


Frost removal.

Designated Health Food

A type of functional food that has been approved by the Ministry of Health, Labor and Welfare as having certain health benefits.


draft。Generally speaking this is the flow of air due to differences in pressure. It refers to the flow of air or gas that occurs in hot air tubes, chimneys, heaters, and indoor spaces. In the case of a heater, it can be said that it is the tendency of air to rise caused by the difference between the specific gravity of the combustion-heated high-temperature exhaust gas and the specific gravity of the normal temperature air being supplied. It also refers to airflow uncomfortable to the human body, and sometimes refers to a drafty wind or natural convection of cold wind from the window in winter.

Dry-Bulb Temperature

Temperature indicated on the dry-bulb side of a wet and dry thermometer (indicating the temperature of dry air).

Dry-Run Prevention Thermostat

A safety device that prevents malfunction of the humidifying heater due to overheating. In our equipment, operation is stopped when the dry-run prevention thermostat activates.

Drying Operation

A simple term for dehumidification operation.① If dehumidification of a room using a home air conditioner is desired without lowering the indoor temperature, then a device with a reheater outside the evaporator could be used. Once the air is cooled down in the room, the temperature and humidity will be reduced, at which point the temperature is raised using a reheater, which in total will affect a drop in humidity without a drop in temperature. Such basic measures are expensive to achieve and are only utilized by a few manufacturers.② In many cases, dry operation through control of a fan is used to achieve the same effect as "dry operation".If the fan controls and blows the air slowly at the lowest speed, the room temperature will gradually decrease and at the same time, the humidity will increase.



Abbreviation of Engine Control Unit. This refers to a microcontroller that performs overall control when an engine is operated using an electronically controlled auxiliary device. It is an important component that could be called the "brain" of a car, and it has become more sophisticated with the advent of modern hybrid cars. Many automobile factories, engine factories, and research and development centers are equipped with our temperature inspection equipment, compact vertical temperature inspection equipment, and temperature testing equipment in order to improve the reliability of cars.


A device that removes water droplets by preventing the scattering of water droplets that accompany the air flow in air conditioners and cooling towers. Usually the water droplets are separated out by utilizing their inertial force in a zigzag folded iron or resin molded plate structure.

Endocrine Disrupting Chemicals

Also referred to as environmental hormones. It refers to chemical substances present in the environment that cause hormonal effects in living organisms or conversely inhibit hormonal effects.

Energy Saving

The reduction of power consumption. Energy savings of 50% to 70% or higher have been realized in some ORION products by adding inverter control to the compressor.

Engine Bench Testing

Starts only the engine to test its durability and performance. Vibration, exhaust efficiency, and fuel consumption are also measured. Our precision air-conditioning equipment (PAP series) is installed in many engine developments, including bench tests for agricultural diesel engines used in tractors as well as by automobile manufacturers.

Environmental Test

An environmental test is a mock test that is performed under actual working conditions of equipment and components. There are various tests such as temperature, humidity, vibration, acceleration, and atmospheric pressure. The main environmental tests being done in the electronics industry related to temperature and humidity are low temperature tests, high temperature tests, high temperature and high humidity tests, temperature cycling tests, and temperature change tests.


Abbreviation of Electric Power Steering. This technology uses an electric motor instead of hydraulic pressure to assist steering, and has the advantages of improved fuel efficiency and increased control freedom. Due to advances in electronic control of the entire vehicle, it has recently come into more widespread use. Our temperature inspection system has been introduced into temperature testing of this research and development area, and for temperature inspections on 100% of the production line. In addition to the electrically operated type, there is also a hydraulic power steering.


Etching is a technique of shaping or surface processing using the corrosive action of chemicals. Anti-corrosive treatment is applied only to surfaces of material that are to remain, and unnecessary parts are dissolved, eroded and etched with a corrosive agent to obtain the desired shape.


An instrument used to heat a liquid in order to vaporize and then and reliquefy it.

Exhaust Gas Recirculation

A technology that suppresses the generation of nitrogen oxides by lowering the maximum flame temperature. This is done by mixing part of the combustion exhaust gas with combustion air for combustion.

External Alarm System

A system that notifies the people outside the operating area of abnormalities inside chambers and rooms by use of a recorder, remote monitor, etc.

External Alarm Terminals

A terminal used for output to alarm systems, etc. mainly using dry (no-voltage) contacts.


Fan Coil

A small air conditioner that discharges temperature-controlled air, and consists of a fan (blower), heat exchanger, and filter. It cannot perform ventilation or humidity control.


Abbreviation for the US Food and Drug Administration: FDA (Food and Drug Administration).
A government-affiliated agency that investigates and exposes products that consumers may come into contact with in normal life, such as harmful foods and chemicals, cosmetics and medical equipment, and toys.

Feedback Control

A control method in which a result controlled by a control signal output from a control system is compared with a set value (target) and a correction operation is performed so as to match the set value (target).


A type of jig that incorporates a pin board. It is also referred to as a pin jig.

Flexural (Bend) Strength

The bending strength is calculated by supporting the test piece horizontally at two fulcrums, applying a load to the center from above, bending the test piece, and reading the maximum load until the test piece breaks.


A method in which a printed circuit board is passed over a bath containing heat-melted liquid solder in order to solder the joints between components and the board.

Fuel Cell

A device that generates electric power using energy generated by the chemical bonding reaction between hydrogen and oxygen. The only byproduct produced from this reaction is water (steam).Therefore, since it is clean and has high power generating efficiency, it is seen as one solution to the problem of global warming. At present, companies are competing for commercialization of this technology in areas such as the development of fuel cell vehicles and household fuel cells.

Fuel Cell Vehicle

An electric vehicle equipped with a fuel cell as a power generator.

Functional Food

Food that enhances bioregulatory function other than nutrition or taste. Beverages with dietary fiber, etc.


Generic Drugs

Drugs which are manufactured by imitating original drugs whose patents have expired.


Hand Assembled

In terms of the soldering process, it means to use a soldering iron to solder individual components using "wire solder".

Heat Conductivity

Rate indicating the amount of heat transfer. Units used are kcal/m⋅h⋅°CThe amount of heat is proportional to the heat transfer area, the temperature difference, and time with a certain proportionality constant, and is also inversely proportional to the distance over which the heat travels. It is this constant of proportionality.

Heat Cycle Test

A test in which parts and products are alternately exposed to high and low temperature atmospheres in a short period of time. By applying temperature changes, the stress of expansion and contraction is repeatedly applied, and fatigue damage such as cracks and peeling is examined.

Heat Distortion Temperature

The temperature at which a resin or plastic will not be able to maintain its shape as a molded product when exposed to a specific heat load of that temperature.

Heat Load

The amount of heat generated from a test piece or work. Because it can be considered as a load as seen coming from the device side, it is expressed in this way.

Heat Resistance

The ability of a material to maintain its physical properties when exposed to high temperatures.

HFC Refrigerant

A refrigerant with a low ozone depletion potential.

High and Low Temperature Storage

Can contain items under high or low temperatures for several hours or even days, after which the items under test can be inspected for any resulting effects. Temperatures and storage times are decided in consideration of relevant standards.

High-Voltage Power Receiving Equipment
("Cubicle" in Japanese)

An enclosed switchboard/distribution panel with built-in main circuity, testing circuity equipment (transformers, circuit breakers, switches, instruments) and supervisory control devices.

Humidification Water

Water used to humidify a chamber. We recommend using conditioned water.

Humidity and Thermal Shock Testing

This is condensation cycle testing. Humidity is controlled when there is exposure to high temperature. A high-temperature/high-humidity environment is repeatedly created, and during this time, the effects of condensation are assessed.

Humidity Distribution

The distribution of humidity within a chamber. Chamber manufacturers often carry out measurements according tot he JTM (Japan Testing Machine Industry Association) guidelines.

Humidity Range

The humidity range at which the inside of the chamber can be controlled.

Humidity Sensor

A sensor which measured humidity. It has an accuracy higher than that of a web-bulb sensor but requires calibration.

Hybrid IC

Electronic devices, such as IC chips, resistors, and capacitors, are integrated on a single substrate. Small electronic devices can be integrated and handled as a single chip, which enables downsizing and power saving.

Hybrid Vehicle

An automobile that has two power sources, an engine and a motor, and achieves energy savings and low pollution by driving under a combination of their respective operational advantages.


A device used to measure humidity.

Hygrothermal Cycling Test

A test that evaluates durability against temperature and humidity changes in a short period time by repeatedly applying alternating high and low temperatures.


Inspection Chamber

A vessel (chamber) in which a workpiece (sample) is inserted for inspection against temperature, etc.


Boiler pipes, cold water pipes, refrigerant pipes, etc. are coated with heat insulating material mainly for the purpose of keeping warm and cool, and wound and finished with aluminum, stainless steel, steel plate + painted material, etc.

Insulation Material

A material that suppresses heat conduction for the purpose of keeping something warm and/or cool. Fiberglass insulation is a typical insulation material.


An interface is a junction or boundary surface between objects. At ORION, this is indicative of the decided physical connector shape used for communication and the method of signal transmission and reception etc., and, depending on the product, including the PAP Series of precision air processors, can be easily connected with a single cable for operation and temperature control status monitoring from a personal computer, of which there are three standards that support communications functions: RS-232C, RS-422A, and RS-485.The same applies to temperature test equipment.

IP Test

This is a protection rating test of the outer shell of electrical machinery and equipment. IP is an abbreviation of International Protection. This is the rating of protection against foreign matter, dust, and water on the outer shell of electrical machinery. The test evaluation is carried out under a test method standardized to a protection rating.


Abbreviation for International Organization of Standardization, A non-governmental international organization established in 1947 for the purpose of formulating international industrial standards. It consists of standardization bodies in 147 countries and is headquartered in Geneva, Switzerland.



Abbreviation for Japan Testing Machine Industry Association.


Latent Heat

The heat expended when a substance undergoes a change in state from a solid to a liquid or a liquid to a solid without undergoing a change in temperature. The heat of fusion, the heat of evaporation, and the heat of sublimation are collectively referred to as the latent heat of state change.

Lead-free Solder

This refers to solder that does not contain lead. Formerly, leaded solder had been used in large quantities in order to affix electronic components to circuit boards to make electronic circuits and devices. However, lead is not only hazardous to the human body, but also has very harmful effects on the natural environment, so lead-free solder has been developed and its use has been increasing.

Lightfast Testing

A test where light is forcibly applied to an object to test for resulting deterioration due to light.


A device that prevents the electrical current from exceeding a certain level.

Liquid Tank Thermal Shock Test

The thermal shock test uses liquid media. A thermal shock is applied to a test subject by alternately dipping it in high and low temperature liquids. Because it is immersed in a liquid that has already reached the target temperature from the beginning, it can be subjected to a drastic temperature change compared to an air-tank thermal shock test that adjusts the air temperature within the test range.

Load Bearing Specification

A floor surface reinforcement specification in order to allow for placement of items such as tanks filled with heavy material, etc.

Lot Production

Lot production is a method in which multiple products are produced alternately by grouping the production volume for each product type. Since the production volume is not so large as compared with continuous production, the idea of this production method is to collect a certain quantity as a lot, and process such lots regularly. Even if the demand for continuous production is not expected, it is considered to be a production method used in cases where the production quantity is not small enough to be able to respond to individual production orders.



The basic element of a substance. These are the smallest particles that do not lose their elemental chemical properties.

Mounting Substrate Environmental Testing

A test in which high-temperature, low-temperature, and temperature cycling tests are performed in order to observe solder degradation due to thermal fatigue. Constant temperature and humidity testing can also be performed in order to test for whisker formation. Whiskers are observed and analyzed using a scanning electron microscope (SEM) other other devices.


Non-destructive Test

Inspect of electronic components and circuit boards using radiation and ultrasonic waves which can investigate the safety and quality of products without damaging them.

Noxious Chemical Substances

A general term for chemical substances that have a harmful effect on humans, animals and plants through their presence in the environment. Specifically, substances that may cause damage to human health or the inhabitation and growth of animals and plants are specified in the Air Pollution Control Act, the Water Pollution Control Act, the Chemical Substances Control Law, the Dioxin Special Measures Law, etc. are considered to be noxious chemicals.


Observation Window

An observation window installed to allow viewing of the test sample inside.

Overheat-Prevention Thermostat

A safety device that prevents failure of a heater due to abnormal heat generation. In our equipment, when the overheat prevention thermostat is activated, equipment operation stops.


Peltier Device

A Peltier device is an electronic component that is a type of thermoelectric device. A plate-shaped semiconductor element utilizing the Peltier effect in which heat flows from one metal to the other when current flows through the junction of two types of metals.


Indicates items that are used to diagnose, treat and prevent diseases, and are examined for quality, effectiveness, and safety, and are approved by the Minister of Health, Labor and Welfare and the prefectural governor. Areas such as development, production, and use are regulated by the Pharmaceutical Affairs Law.

Pharmaceutical Affairs Law

In order to ensure the quality, effectiveness and safety of pharmaceuticals, quasi-drugs, cosmetics and medical devices, necessary regulations are made regarding their production, distribution, sales, import, export, etc. The law is aimed at improving health and hygiene, and, with the exception of some parts, is under the jurisdiction of the Ministry of Health, Labor and Welfare.


A generic term for substances that are secreted outside the body of animals and cause certain behaviors and physiological responses in other individuals of the same species.


A substance that promotes a chemical reaction under the light of the sun or fluorescent lights without the substance changing itself.

PID Control

Also known as proportional integral derivative operation. The control operation generally referred to as PID is one in which an integral operation and derivative, operation are added to a proportional operation. Stable proportional control without offset can be performed by appropriately setting the proportional band, the integration time, and the differentiation time.

Plastic Waste

Various types of plastic products discarded after use and plastic-based waste including scrap and waste tires generated during manufacturing processes.

Platinum Resistance Thermometer

A sensor that uses platinum (Pt) as a temperature-measuring element, which acts as a kind of "temperature-measuring resistor" that utilizes the property that the electrical resistance of metal changes with temperature. These devices are also used for temperature observation by the Japan Meteorological Agency.

Power Consumption

The amount of power that a device or machine consumes.

Pressure Gauge

An instrument that measures the pressure of a liquid or gas.

Printed Circuit Board

A bare printed circuit board on which various electronic parts and devices are mounted and soldered in order to operate as a circuit.


A part that constitutes part of a detector device that measures the electrical and mechanical characteristics of a sample by approaching a specific part of the sample. Many probes are shaped like a needle or pin.

Program Control

A control method in which target values ​​such as temperature and pressure are changed over a predetermined time.

Proportional Control

Another name for PID control.



Differentiated from pharmaceuticals based on the Pharmaceutical Affairs Law. A drug that has a mild effect on the human body, and is classified at an intermediate position between pharmaceuticals and cosmetics. These are equivalent to toothpaste, spray insecticide, mosquito coils, sunscreen cream, etc.


Recovery Time

This refers to the time when a device is stopped as a result of a power failure due to a natural disaster or other shutdown, from the time the power is restored until the device starts operating again.

Recycled PET Fiber

A chemical fiber made from recycled PET bottles.


A solder paste also known as "cream solder" is printed on the printed circuit board in advance using a pre-set pattern and components are mounted on the paste. Then, heat is directly applied to the printed circuit board in order to melt the solder, and in this way, the attached components are soldered to the board.

Refrigeration Capacity

The ability to cool objects using a refrigeration system. Units are often expressed in "tons" of refrigeration.

Relative Humidity

The ratio of the specific weight of humid air to the specific weight of saturated air. Also, it is the ratio expressed as a percentage of the partial pressure of water vapor in humid air to the partial pressure of moisture in saturated humid air at the same temperature. The term humidity generally refers to relative humidity.

Reliability Testing

Reliability testing is a battery of tests and inspections performed on a product before it is put on the market. Through these tests, reliability is confirmed, defects are fixed, and reliability is improved.

Remote Sensing

A technology that uses a sensor mounted on an artificial satellite or aircraft to capture an image object from a distance. In order to accurately interpret and analyze data (images) obtained by remote sensing, field surveys are conducted at as many points as possible, knowledge on how reality is recorded in images is accumulated, and accuracy is improved.

Resistance Temperature Detector

A temperature sensor which measures changes in temperature as changes in electrical resistance. Materials such as platinum, nickel, copper, and others are used and measurements may be taken in 3-wire and 4-wire configurations.

Risk Management

Examining, deciding, and implementing measures to reduce environmental risks which were determined by risk assessment. Based on the results of the risk assessment, comprehensive judgments are made in consideration of economic and social conditions, public opinion, and the like. It can be considered to be the process which involves policy decisions.

Rotating Light

When an abnormality occurs in a device, the light flashes like that of a police car to notify operators of the abnormality.


Saturated Aqueous Solution

A solution of a solute dissolved in water at a certain temperature such that no more solute can be dissolved into the solution.

Sensible Heat

Heat that changes the temperature of an object without incuring a phase change.

Sequence Control

Sequence control is the starting and stopping of equipment or various controls that follows a given procedure. The control of each item is sequentially advanced in a predetermined order.

Smart Grid

A smart grid is a power network that utilizes communication and control functions and devices such as smart meters in order to prevent power outages, adjust power transmission, enable various power contracts, and reduce labor costs.

Smart Meter

The device that forms the basis of smart grids is the smart meter. These devices are terminals used to collect information about the amount of power used in businesses and homes. Our in-line type temperature test tank and compact vertical type temperature test devices are adopted. for this environmental test.

Solder Resist

Solder resist is a thermosetting epoxy resin film applied to a printed circuit board such that copper foil is only exposed for parts that require soldering, and solder does not adhere to the areas that do not required solder. Solder resist is applied at the final stage of the printed board manufacturing process.

Specific Heat

The capacity of heat per 1 gram of a substance.

Specific Humidity

The ratio of the mass of water vapor contained in a volume of air to the total mass of that volume of air. The units are kg/kg.

Stretch Ratio

When conducting a tensile test, mark two lines at some distance from the center of the test piece and measures the distance between those lines when the test piece breaks. The value expressed is a percentage of how much the piece stretched.


Temperature and Humidity Control Range

A temperature/humidity range that can be reproduced in a chamber. Often used in catalogs and specification tables, the control range of temperature and humidity is indicated by a line on a graph where humidity is on the vertical axis and temperature is on the horizontal axis.

Temperature Change Test

A temperature test is often included when performing environmental tests. This temperature test is aimed at investigating the effects of changes in physical properties, such as changes in product dimensions due to temperature changes, examining the operating characteristics, and confirming the durability as to whether or not permanent changes such as damage may occur. There are rapid temperature change tests (thermal shock tests) and constant speed temperature change tests (temperature cycling tests).

Temperature Distribution

The difference between the temperature at the center of a chamber and the temperature at any selected point in the effective space. For large spaces like temperature-controlled rooms, a scheme to reduce this difference while pursuing energy savings falls on the technical know-how of the company.

Temperature Sensor

An type of sensor that detects the temperature inside and outside a chamber, or in hot/cold water, etc., and outputs a signal that is easy to use for control and measurement. Some types of sensors are thermocouples, platinum resistance thermo-sensors, thermistors, etc., but platinum resistance thermo-sensors are often used in our temperature test equipment.

Temperature Setting Range

The temperature range that can be reproduced in the chamber.

Tensile Modulus of Elasticity

In the case of a tensile test, a curve can be obtained by attaching a DHF or foil strain meter to the test piece and recording the relationship between the load and the elongation between marked lines. Related to this is the inclination of the first straight line portion as it corresponds to the tensile elasticity (Young's modulus).

Tensile Strength

In order to measure tensile strength, a dumbbell-shaped test piece having a narrow central portion is used to collect tensile stress by holding both ends with a gripper and pulling at a constant speed until the test piece breaks. It represents the value obtained by dividing the maximum load at that time by the original minimum cross section of the test piece.

Thermal Expansion

A phenomenon in which the volume of an object increases as its temperature rises.

Thermal Shock

Causing a sudden temperature change in an object. Doing so can induce fatigue induced degradation into the materials and material properties of the object.

Thermal Shock

The rapid change in temperature applied to an object may cause deterioration due to fatigue of its materials. This is referred to as thermal shock.

Thermal Shock Testing

A test where the temperature is suddenly changed. The rapid temperature change test alternately exposes an item to high and low temperatures. This is similar to a constant speed temperature change test, but the change in temperature is abrupt, from within several seconds to tens of seconds. In addition to this rapid temperature change, stress that from differences in heat capacity and the thermal time constants of each component also take place. The test is used to check and investigate how resistant electronic components and devices behave when exposed to changes in ambient temperature.

Thermal Time Constant

The thermal time constant is a constant that indicates the degree of thermal responsiveness of a material. For example, even if the measured target changes from 100 °C. to 0 °C., the temperature of the element itself does not change suddenly but gradually changes to 0 °C. The thermal time constant indicates the time required for the element to change from a state where the element is maintained at one temperature to another temperature. A change of 63.2% of the final temperature is normally used as a standard value.


A thermistor is a semiconductor device whose resistance is highly dependent on temperature such that the resistances decreases as the temperature rises. These devices have a low heat capacity but high sensitivity.


Also known as a thermoelement. Two dissimilar metal wires are bonded together and when heat is applied, a temperature-dependent voltage is produced as a result of the thermoelectric effect. The temperature can be measured by measuring the resulting voltage.


Two types of metal wire are joined, and a pair of conductors are attached which generate a DC voltage (in the mV range) corresponding to temperature. A thermoelectromotive force is generated due to the temperature difference between the reference point and the measurement point, and the temperature is detected by measuring the electromotive force by electrically connecting one end of two kinds of metals. Combinations of metals used to form the thermocouple include platinum + platinum-rhodium, chromel + alumel, chromel + constantan, iron + constantan, copper + constantan, and others.


A temperature regulation device used to automatically maintain a constant temperature through use of a bimetal or mercury.

Thermostatic Chamber

Test equipment that can maintain constant temperature for extended periods of time regardless of external temperature conditions and can also perform temperature cycling testing.

Toxic Substances

Although simply being termed a toxic substance is a very broad concept, the Air Pollution Control Law states them to be used in "combustion, synthesis, decomposition and other treatment (excluding mechanical treatment).Also cadmium, chlorine, hydrogen fluoride, lead and other substances that may cause damage to human health or the living environment and are specified by Cabinet Order. (Article 2, Paragraph 1, Paragraph 3 No. 3, Article 2).In addition to the substances listed in the Cabinet Order, cadmium compounds, hydrogen chloride, fluorine, silicon fluoride, lead compounds, and nitrogen oxides are also specified.

Toxic Substances Control Act

U.S. law on the regulation of the production of toxic chemicals. Established in 1976, this law aims to regulate the irrational risks to human health and the environment caused by chemical substances.

Trend Graph

A graph that shows a trend, or tendency toward a certain point.



The design is scientifically based and validatable, and includes verification that the design will meet its intended goals.

Variable Air Volume Controller

A device that is installed in the middle of a duct or at a terminal point to limit the amount of air supplied by varying the air flow rate.

Variable Air Volume System

An all-air air conditioning system that varies the amount of air supplied to the air conditioning target according to the change in indoor heat load.

Vibration Testing

Vibration or shock testing for the purpose of evaluating how well a part or assembly can withstand actual environmental conditions. Vibration testing is performed on a wide range of applications, from printed circuit boards and aircraft to automobiles and home appliances.


Water Absorption

The test piece is immersed in distilled water for a certain period of time at a constant temperature, and the ratio between the weight increase and the original weight is expressed as a percentage. Moreover, it may also be represented as the amount of water absorption per unit of surface area of an object.

Water Supply Problem Alarm

Alarm that occurs when water is not supplied to the humidifying tray for a certain period of time.

Water Treatment Chemicals

Natural water contains calcium and chlorides. When this is used as industrial water for factory manufacturing equipment and the like, such water also causes corrosion of equipment and piping. Water treatment chemicals are used to prevent damage due to such water-induced corrosion.

Wet and Dry Bulb Thermometer

Hygrometer that measures humidity and temperature simultaneously by measuring both wet-bulb and dry-bulb temperatures

Wet-Bulb Temperature

A temperature used in combination with the dry-bulb temperature in order to determine the relative humidity of air.


The state in which the molten solder tends to spread over the metal. The wettability varies depending on the type of metal, the type of flux, and the state of dirt and roughness on the metal surface.


Whiskers are whisker-like metal crystals generated on the surface of plating films. If they causes a short circuit between adjacent wires, a signal failure may occur and the electronic device may malfunction.


Although the names in each industry are different, it is also referred to as a test piece, specimen, or sample, etc.


Zero-power Resistance

This refers to the resistance of a thermistor measured at a specific temperature that has a power consumption low enough that the change in resistance due to self-heating is insignificant and can be ignored compared to the total error in measurement.