Establishments primarily engaged in manufacturing industrial instruments and related products for measuring, displaying (indicating and/or recording), transmitting, and controlling process variables in manufacturing, energy conversion, and public service utilities. These instruments operate mechanically, pneumatically, electronically, or electrically to measure process variables, such as temperature, humidity, pressure, vacuum, combustion, flow, level, viscosity, density, acidity, alkalinity, specific gravity, gas and liquid concentration, sequence, time interval, mechanical motion, and rotation. Establishments primarily engaged in manufacturing electrical integrating meters are classified in Industry 3825; those manufacturing residential and commercial comfort controls are classified in Industry 3822; those manufacturing all liquid-in-glass and bimetal thermometers and glass hydrometers are classified in Industry 3829; those manufacturing recorder charts are classified in Industry Group 275; and those manufacturing analytical and optical instruments are classified in Industries 3826 and 3827.

• Absorption analyzers, industrial process type: e.g., infrared, X-ray
• Analyzers, industrial process type
• Annunciators, relay and solid-state types: industrial display
• Boiler controls: industrial, power, and marine type
• Buoyancy instruments, industrial process type
• Chromatographs, industrial process type
• Combustion control instruments, except commercial and household
• Computer interface equipment for industrial process control
• Controllers for process variables: electric, electronic, and pneumatic
• Coulometric analyzers, industrial process type
• Data loggers, industrial process type
• Density and specific gravity instruments, industrial process type
• Differential pressure instruments, industrial process type
• Digital displays of process variables
• Draft gauges, industrial process type
• Electrodes used in industrial process measurement
• Electrolytic conductivity instruments, industrial process type
• Flow instruments, industrial process type
• Fluidic devices, circuits, and systems for process control
• Gas and liquid analysis instruments, industrial process type
• Gas flow computers, industrial process type
• Humidity instruments, industrial process type
• Hydrometers, industrial process type
• Industrial process control instruments
• Infrared instruments, industrial process type
• Level and bulk measuring instruments, industrial process type
• Liquid analysis instruments, industrial process type
• Liquid concentration instruments, industrial process type
• Liquid level instruments, industrial process type
• Magnetic flow meters, industrial process type
• Manometers, industrial process type
• Moisture meters, industrial process type
• Nuclear reactor controls
• Panelboard indicators, recorders and controllers: receiver type
• Potentiometric self-balancing instruments, except X-Y plotters
• Pressure gauges, dial and digital
• Pressure instruments, industrial process type
• Primary elements for process flow measurement: orifice plates
• Programmers, process type
• Pyrometers, industrial process type
• Refractometers, industrial process type
• Resistance thermometers and bulbs, industrial process type
• Telemetering instruments, industrial process type
• Temperature instruments: industrial process type, except glass and
• Thermal conductivity instruments, industrial process type
• Thermistors, industrial process type
• Thermocouples, industrial process type
• Thermometers, filled system: industrial process type
• Time cycle and program controllers, industrial process type
• Transmitters of process variables, standard signal conversion
• Turbidity instruments, industrial process type
• Turbine flow meters, industrial process type
• Viscosimeters, industrial process type
• Water quality monitoring and control systems