Instrumentation and Thermodynamics Vocabulary

A comprehensive list of vocabulary and formulas regarding physics, pressure, temperature, and fluid measurement based on the lecture notes.

ABSOLUTE PRESSURE

Pressure measured with reference to a perfect vacuum.

ABSOLUTE TEMPERATURE SCALE

A temperature scale that begins at absolute zero.

ABSOLUTE ZERO

The theoretical temperature at which molecular motion ceases ($0\,K$ or $-273^{\circ}C$).

ABSORPTION DYNAMOMETER

A dynamometer that absorbs mechanical power and converts it into heat while measuring engine output.

ACCURACY

The degree to which a measured value is close to the true value.

AIR

A mixture of dry air and water vapor.

AIR PROPERTIES

The physical properties of moist air, such as temperature, humidity, enthalpy, and specific volume.

AREA

The amount of surface covered by a two-dimensional shape, measured in square units.

ATMOSPHERIC AIR

Natural air composed mainly of nitrogen, oxygen, and water vapor.

BELLOWS

An elastic pressure-sensing element that expands or contracts when pressure is applied.

BOURDON TUBE

A curved elastic metal tube that tends to straighten when pressure is applied and is commonly used in pressure gauges.

BRAKE HORSEPOWER (BHP)

The actual usable power delivered by an engine at its output shaft, measured using a dynamometer.

BRAKE POWER

The useful mechanical power available at an engine's crankshaft after friction losses.

CAPILLARY VISCOMETER

A viscometer that measures viscosity by determining the time required for a liquid to flow through a narrow capillary tube.

CAPSULE

A pressure-sensitive elastic element made of two joined diaphragms that deform when pressure is applied.

CELSIUS ($^{\circ}C$)

A temperature scale in which water freezes at $0^{\circ}C$ and boils at $100^{\circ}C$ under standard atmospheric pressure.

CENTIMETER ($cm$)

A metric unit of length equal to one-hundredth ($1/100$) of a meter.

CHRONOMETER

A highly accurate instrument used to measure time precisely.

CLOCK

An instrument used to measure and display time.

COMBUSTION

A chemical process in which a substance burns and releases heat energy.

CONTACT TEMPERATURE MEASUREMENT

Measuring temperature by placing the sensing element in direct contact with the object.

CUBIC METER ($m^3$)

The SI unit of volume.

DENSITY ($\rho$)

The mass of a substance per unit volume.

DENSITY FORMULA

$$\rho = m/V$$

DIFFERENTIAL PRESSURE

The difference in pressure between two points in a fluid system.

DIAPHRAGM

A flexible elastic membrane that bends when pressure is applied and is used as a pressure-sensing element.

DISCHARGE

The volume of fluid flowing through a system per unit time, also called flow rate.

DISTANCE

The total length of the path traveled by an object regardless of direction.

DISTANCE FORMULA

$$\text{Distance} = \text{Speed} \times \text{Time}$$

DRY AIR

Air that contains no water vapor.

DRY BULB TEMPERATURE (DBT)

The actual air temperature measured by a thermometer shielded from moisture.

DYNAMOMETER

An instrument used to measure the force, torque, and mechanical power produced by an engine or rotating machine.

DYNAMOMETER TEST

A test performed to determine the power, torque, or force produced by a machine.

ELECTRICAL RESISTANCE PRESSURE GAUGE

A pressure gauge that measures pressure through changes in electrical resistance.

ELECTRICAL RESISTANCE THERMOMETER (RTD)

A temperature sensor that measures temperature through changes in electrical resistance.

ELECTRIC DIRECT-CURRENT (DC) DYNAMOMETER

A dynamometer that uses a DC motor or generator to absorb or supply mechanical power.

ELASTIC ELEMENTS

Pressure-sensitive components that deform when pressure is applied.

ENTHALPY

The total heat energy contained in moist air.

ENGINE POWER

The rate at which an engine performs mechanical work.

EVAPORATION

The process by which liquid water changes into water vapor by absorbing heat.

EXPANSION THERMOMETER

A thermometer that measures temperature through the expansion of a liquid or gas.

FAHRENHEIT ($^{\circ}F$)

A temperature scale commonly used in the United States.

FALLING BALL VISCOMETER

A viscometer that measures viscosity by timing how long a ball takes to fall through a liquid.

FEET ($ft$)

A unit of length in the Imperial System.

FLOW

The movement of a liquid or gas through a pipe or channel.

FLOW MEASURING EQUIPMENT

Devices used to determine the volume or flow rate of fluids.

FLOW RATE ($Q$)

The quantity of fluid passing through a cross-section per unit time.

FLOW RATE FORMULA

$$Q = \text{Volume} \div \text{Time}$$

FLOWMETER

An instrument used to measure the flow rate of a fluid.

FOOT RULE

A rigid measuring tool used for measuring short distances.

FORCE ($F$)

A push or pull exerted on an object.

GAUGE PRESSURE (RELATIVE PRESSURE)

Pressure measured relative to atmospheric pressure.

HEAD

The height of a liquid column representing pressure or energy.

HEAT

Energy transferred because of a temperature difference.

HELICAL TUBE

A coiled elastic tube used as a pressure-sensing element.

HORSEPOWER (HP)

A unit of mechanical power equal to approximately $746\,\text{watts}$.

HOUR ($hr$)

A unit of time equal to $60\,\text{minutes}$ or $3,600\,\text{seconds}$.

HUMIDITY

The amount of water vapor present in the air.

HUMIDITY MEASUREMENT

The process of determining the moisture content of air.

HYDRAULIC DYNAMOMETER

A dynamometer that uses water resistance to absorb mechanical power.

HYDRAULIC MEASUREMENT

The measurement of liquid flow, pressure, or volume in hydraulic systems.

HYDROMETER

An instrument used to measure the specific gravity or density of liquids.

INCLINED TUBE MANOMETER

A manometer with an inclined tube used for measuring small pressure differences with greater sensitivity.

IONIZATION GAUGE

A vacuum gauge that measures very low pressure by ionizing gas molecules.

JOULE ($J$)

The SI unit of work and energy.

KELVIN ($K$)

The SI base unit of thermodynamic temperature.

KILOMETER ($km$)

A metric unit of length equal to $1,000\,\text{meters}$.

KILOMETER PER HOUR ($km/h$)

A common unit of speed.

LAMINAR FLOW

Smooth, orderly fluid flow in parallel layers with little mixing.

LASER DISTANCE METER

An instrument that measures distance using laser technology.

LATENT HEAT

Heat absorbed or released during a change of state without changing temperature.

LENGTH

The distance between two points.

LENGTH MEASURING INSTRUMENT

A device used to measure the dimensions or distance of an object.

LITER ($L$)

A metric unit of volume equal to $1,000\,\text{cubic centimeters}$.

LIQUID

A state of matter with a definite volume but no fixed shape.

MANOMETER

An instrument used to measure fluid pressure by comparing the height of a liquid column.

METER ($m$)

The SI base unit of length.

MCLEOD GAUGE

A vacuum gauge that measures very low pressure by compressing a known volume of gas.

NEGATIVE PRESSURE

Pressure produced when an object is pulled rather than pushed.

ORIFICE METER

A flow-measuring device that determines flow rate by measuring the pressure drop across an orifice.

PASCAL ($Pa$)

The SI unit of pressure equal to one Newton per square meter.

PITOT TUBE

An instrument used to measure fluid velocity by comparing stagnation and static pressures.

PLANIMETER

An instrument used to measure the area of irregularly shaped figures.

POSITIVE PRESSURE

Pressure produced when a force pushes on an object.

PRESSURE

The force exerted per unit area on a surface.

PRESSURE FORMULA

$$P = F \div A$$

PRESSURE THERMOMETER

A thermometer that measures temperature by the pressure change of a confined fluid.

PRONY BRAKE

A simple absorption dynamometer that measures brake power by applying friction to a rotating shaft.

PSYCHROMETER

An instrument used to measure humidity using dry-bulb and wet-bulb temperatures.

PSYCHROMETRIC CHART

A graphical chart showing the thermodynamic properties of moist air.

PIRANI GAUGE

A vacuum gauge that measures low pressure by the heat transfer from a heated filament.

RANKINE ($^{\circ}R$)

An absolute temperature scale based on the Fahrenheit degree.

REYNOLDS APPARATUS

A laboratory apparatus used to demonstrate laminar and turbulent flow.

ROTATIONAL VISCOMETER

A viscometer that measures viscosity by the torque required to rotate a spindle in a liquid.

SHOP-TYPE DYNAMOMETER

A dynamometer commonly used in workshops for testing engine power and performance.

SPECIFIC GRAVITY (SG)

The ratio of the density of a substance to the density of water.

SPECIFIC GRAVITY FORMULA

$$\text{Specific Gravity} = \frac{\text{Density of Substance}}{\text{Density of Water}}$$

SPEED

The distance traveled per unit time.

SPEED FORMULA

$$\text{Speed} = \text{Distance} \div \text{Time}$$

SPRING DYNAMOMETER

A dynamometer that measures force through the extension or compression of a spring.