Gas flow switches and liquid flow switches, velocity, are used to measure the flow or quantity of a moving fluid in terms of velocity, such as feet per minute

Liquid level switches are used to detect specific liquid levels or interfaces between liquids. These level measurements are indicated via an electrical switching action

Flow meters (flowmeters) and flow sensors are devices used for measuring the flow rate or quantity of a moving fluid or gas

Liquid level sensors are used to detect liquid levels or interfaces between liquids such as oil and water or liquids and solids. 

Mass liquid flow switches and mass gas flow switches are devices used for measuring the flow or quantity of a moving liquid or gas in terms of a unit of mass per unit time, such as pounds per minute. These devices may be sensors with electrical output or may be stand-alone instruments with local displays and controls

Volumetric liquid flow switches are devices with a switch output used for measuring the flow or quantity of a moving fluid in terms of a unit of volume per unit time, such as liters per minute. 

Liquid leak detectors sense when a liquid is leaking from a pipe, tank, or other receptacle area

Flow computers, totalizers, and rate indicators integrate the functions of flow and temperature measurement, computation, data acquisition, input / output (I/O) standardization, and closed loop control. They require external sensor inputs and may be used as local rate indicators

Gas flow meters are used for measuring the flow or quantity of a moving gas in an enclosed pipe or passage

Paddlewheel flow meters have a paddle wheel that is perpendicular to the flow path. The rotor axis is positioned to limit contact between the paddles and the flowing media

Volumetric gas flow switches are devices with a switch output used for measuring the flow or quantity of a moving gas in terms of a unit of volume per unit time, such as cubic feet per minute

Liquid flow meters are used for measuring the flow or quantity of a moving fluid

Turbine flow meters measure the rate of flow in a pipe or process line via a rotor that spins as the media passes through its blades

Level switches, all types, is a generic search form for devices that are used to detect liquid or powder levels, or interfaces between liquids. These level measurements are indicated via an electrical switching action

A mass flow meter is a device that consist of a mass flow sensor or transducer and signal processing electronics.  Fluid (liquid or gas) flow is measured in mass rate units (lbs/min