There are many types of instruments used to measure absolute or gauge pressure. Pressure measurement devices can be separated into two categories: mechanical and electronic.
Level measurement devices can detect, indicate, and/or help control liquid or solid levels. Level measurement devices can be separated into two categories: direct, or mechanical, measurement and electronic measurement.
pH meters and controllers are used to measure and monitor the pH level of a substance.
Spectrometers use light wavelengths to investigate the chemical composition of a sample. Atomic spectrometers use an analytical method by which one or several elements in unknown mixtures can be detected.
Sight flow indicators (SFIs) allow plant engineers to monitor the flow and condition of gases, liquids, or granular solids in a system.
Refractometers measure the refraction of a beam of light in a fluid to determine the concentration of a substance dissolved in it.
Humidity is a measure of the amount of water vapor in the air. It is generally reported as relative humidity, absolute humidity, or dew point temperature.
Gas and flame detectors determine the presence of a gas or fire, respectively. Gas monitors check or regulate the amount of gas present. The gas detectors pictured below detect carbon monoxide and hydrogen sulfide.
A conductivity meter measures an aqueous solution's ability to carry an electrical current.
Colorimeters measure the absorbance and transmittance of light through a fluid sample.