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

Air valves allow metered fluid flow in one or both directions. They are used in pneumatic circuits to regulate the rate of activation or exhaust of cylinders and other pneumatic devices

Control valves or proportional valves are power-operated devices used to modify fluid flow or pressure rate in a process system

Steam valves are used to control the flow and pressure level of steam and heated water vapor

Needle valves are small valves used for flow control in liquid or gas services. The fine threading of the stem and the large seat area allow for precise resistance to flow

Butterfly valves control flow through a circular disc or vane by turning the valve's pivot axis at right angles to the direction of flow in the pipe. They are normally used as throttling valves to control flow

Check valves are self-activating safety valves that permit gases and liquids to flow in only one direction, preventing process flow from reversing. They are classified as one-way directional valves. 

Ball valves provide tight shut-off and characterizable control. They have high rangeability due to the design of the regulating element, without the complications of side loads typical of butterfly or globe valves.

Globe valves are linear motion valves with rounded bodies, from which their name is derived.  They are widely used in industry to regulate fluid flow in both on/off and throttling service. 

Gas valves are used to handle and control the flow of gaseous media such as liquefied petroleum and natural gas. They are made of metal or plastic and vary in terms of valve size, pressure rating, number of ports, and flow

Diverter valves direct flow from one inlet to one of two or more outlets

Hydraulic valves contain and transfer the flow and pressure of hydraulic fluid in hydraulic power systems. They range from simple shutoff valves to precision control valves

Solenoid valves are devices that use a solenoid to control valve activation.

Sanitary valves are designed for applications requiring clean or sterile processing. 

Mixing valves combine the flow of two or more inlets into a single outlet for applications such as temperature and concentration control