You probably know a range of classic pneumatic valves if you work in any type of laboratory or manufacturing environment using liquids or gases. A pneumatic valve is used to control, manage, and handle the flow of media, liquids, and gases through a system.
Types of Pneumatic Valves
In essence, pneumatic valves fall into two different categories. A pneumatic valve with air or inert gas as its driving force is called a pneumatic valve. Within an automated system, these valves control or manage the source air. Although pneumatic valves are frequently referred to as pneumatic, they can be operated manually, pneumatically, solenoidally, or motorized. For an automated system, all serve the same purpose: modulating or controlling the source air. These pneumatic valves can be a gate, plug, diaphragm, wedge, or ball designs, depending on the system specification and plumbing line size.
The drive air or inert gas is handled by these valves, which can be actuated in a variety of ways. For manufacturing processes, these pneumatic valves are frequently used to control, manage, or handle Clean Dry Air (aka CDA). In addition to driving other pneumatic devices, the CDA acts as a source of air for other pneumatic devices (valves, pumps, etc.). Those pneumatic devices may modulate process media or move mechanical components.
In the second type of pneumatic valve, the media is a process fluid or gas, which is controlled, managed, or handled by the valve. It has a pneumatic actuator that is powered by air or an inert gas (also known as CDA). Pneumatic valves are controlled by CDAs or source air (open, closed, or partially open). With its pneumatic actuator, the pneumatic valve will modulate the flow of media within the process.
The industry uses pneumatic valves for automation control and process fluid handling. Pneumatic actuation remains the most cost-effective method of actuating valves, despite some displacement from electro-mechanical (servo and stepper motor driven) and hydraulic systems. Within the semiconductor industry, pneumatic systems operate cleaner with less positive-charged ions from metals, for example.
Configurations of Pneumatic Valves
Further differentiation can be found within the types of pneumatic valves available on the market based on their porting configuration. There are a variety of ways in which pneumatic valves can be ported. In the valve porting industry, three major categories are distinguished: the port size, the port style, and the valve way.
- Port Sizing: The diameter of pneumatic valve ports can range from less than 1/16″ to more than 48″
- Port Styles: Port arrangements for pneumatic valves can be categorized into Socket, Threaded, Compression Tube, Flare, and Sanitary.
- Port Ways: There are several types of pneumatic valves, such as 2-Way valves (the most basic inlet and outlet valves), 3-Way valves, and 4-Way valves. The selection of distribution valves is frequently used with multi-way valves. One way represents the valve’s inlet or outlet, while the other multiple ports (or ways) represent the medium flow selection or distribution.
Pneumatic Valve Materials for Construction
Process media are not affected by pneumatic valves used for automation control. Typical materials used to manufacture them include: plated carbon steel, bronze/brass, stainless steel, and a variety of industrial-grade plastics (PVC, Nylon, Acetal, etc.).
Automation control pneumatic valves are driven by highly conditioned, filtered, and dried pneumatic media (typically CDA air or inert gases). Consequently, the media’s aggressive corrosive nature and high purity level do not have to be considered when designing the valve.
A pneumatic valve is essential for handling the media in the process fluid. One of the most important factors in choosing a pneumatic valve is the media. They are suitable for handling highly acidic, corrosive alkaline, and/or high purity media. To protect the media and the valve, the designer must select materials of construction for all wetted surfaces of the valve. No matter whether the Pneumatic Valve is handling 85% sulfuric acid or 18MegaOhm DI water, it must be designed to protect the media.
Polytetrafluoroethylene (PTFE) as a Construction Material
When considering pneumatic valves for process fluid handling, the materials of construction must be taken into account first. Pneumatic valves made of PTFE are used in critical media processes. PTFE valve bodies, diaphragms, bellows, and plugs are configured so that virgin pure PTFE contacts only the media. The original sintered Polytetrafluoroethylene (PTFE) material is free of any impurities, regrinds, or recycled plastics.
It is possible to use PTFE Pneumatic Valves with the harshest low-pH acids, the most corrosive alkalines, and the purest media. Inert and highly chemical-resistant, PTFE is by its nature an exceptionally inert material. For the handling of critical media, it is frequently one of the best materials for pneumatic valves.