Analytical Instruments
pH Meters: Used for measuring the pH level of liquids.
Conductivity Meters: Measure the electrical conductivity in a solution, often used in water quality testing.
Recording and Display Instruments
Chart Recorders: Devices that record various process conditions against time on a paper chart.
Digital Displays: Used to show measurements digitally for easy monitoring.
Switches and Relays
Pressure Switches: Activated by a change in pressure.
Temperature Switches: Trigger based on temperature changes.
Safety Instruments
Gas Detectors: Devices used to detect the presence of gases in an area, often used as part of a safety system.
Safety Valves: Designed to open to relieve excess pressure and prevent explosion.
Analog Instruments
Provide output in a continuous form, usually as needle movements on a dial. Analog instruments are often valued for their precision and simplicity.
Example: Analog voltmeter.
Digital Instruments
Provide numerical output on a digital display, offering high accuracy and the ease of direct reading.
Example: Digital multimeter.
Passive Instruments
Require external power to operate because they do not generate output on their own.
Example: Strain gauge which requires an external power source for its operation.
Active Instruments
Generate output signals on their own, often using internal power sources or the energy of the measured property.
Example: A thermocouple that generates a voltage in response to temperature differences.
Deflection Instruments
Indicate a measurement by the movement of a pointer across a scale in response to changes in the physical condition being monitored.
Example: Ammeter using a moving coil to indicate current flow.
Null Instruments
Balance a known against an unknown value to achieve a zero or null condition. They are used for high-precision measurements.
Example: Wheatstone bridge for precise measurement of electrical resistance.
