Diaphragm valves comprise one of many different process control valve designs, each with specific attributes making them better suited for certain applications. Selecting the right valve type for an application is a critical early step toward successful control implementation.
Familiarity and understanding of how a particular valve type functions are necessary when equipping a fluid control system. Here are some considerations for valve operation that come into play.
Media Compatibility: Industrial process control applications cover an immense range of viscosity, velocity, solids content, and other physical media characteristics that may, or may not, be acceptably addressed by some valve types.
Cycle Frequency: Some valve types are more suitable for a high frequency of on/off cycles, others are better suited to slower rates.
Compatibility With Sanitary or Similar Operations: Some industries have requirements for special cleaning, sanitizing, or sterilizing of the process flow path. A valve design that does not trap the media within the valve body and allows for full exposure of the fluid path to whatever cleaning agent is applied has certain advantages for these applications. Some cleaning operations also require a full bore or straight-through flow path to allow for proper cleaning.
Operating Speed: Different valve types may have varying capabilities to provide a rapid change of valve position. The valve operating speed must be compatible with process requirements that may call for either rapid or slow opening or closing.
Throttling Ability: Each valve type, through the characteristics of its closure mechanism, offers comparatively different capacities for regulating fluid flow across an extended range between completely closed and fully open.
Space Requirements: Different valve trim arrangements can predicate how much installation space a valve may require for proper operation and maintenance. For example, a valve with a rising stem will generally require more clearance than a similar capacity valve with a rotating stem.
GEMU Model 620 Industrial Diaphragm Valve
Certainly, there are more aspects of valve operation that will be taken into account in the selection process. Diaphragm valves defend their niche of applications with their ability to:
Provide on/off or throttling service
Eliminate stem leakage
Provide bubble-tight service
Eliminate pockets that may trap media
Isolate valve mechanism from media
Prevent contamination of media by valve parts or operation
Below is a short video that provides an animated look inside a weir diaphragm valve. The video provides a clear illustration of how the fluid flows through the valve and how the valve controls the flow. There are variants of the diaphragm valve that do not use a weir, providing a straight-through or full-bore flow path. Their operation is similar.
Watch the video. It’s short and to the point. Get the help you need to solve your process control valve challenges from the seasoned experts at MSEC.
