Diaphragm Valves

Diaphragm valves are related to pinch valves, but use an elastomeric diaphragm, instead of an elastomeric liner in the valve body, to separate the flow stream from the closure element.  Instead of pinching the liner closed to provide shut-off, the diaphragm is pushed into contact with the bottom of the valve body to provide shut-off.  Diaphragm valves are excellent for controlling the flow of fluids containing suspended solids and offer the flexibility of being installed in any position.  These types of valves have found widespread use in the pharmaceutical, food processing, and water treatment industries.

Manual diaphragm valves are ideal for flow control by offering a variable and precise opening for controlling pressure drop through the valve.  Actuated varieties can offer features as adjustable opening, positioners for precise flow control, and electric relay of valve position.

The advantages provided by diaphragm valves are many.  They are extremely clean, and can form a nearly leak-proof seal for tight shut-off.  The diaphragm design provides for easy maintenance and repair as it can be replaced without disturbing the piping line.  However, they are limited they are limited to moderate temperature (-60 to 450°F) and pressure service (approximately 300 psi) by the mechanical properties of most common diaphragm materials. They cannot be used in multi-turn operations. 

Diaphragm valves are available in two basic forms: weir type and straight through types.

The weir design is best for general use applications or for tough corrosive and abrasive services.  The straight through type can be used in situations where the flow direction changes within the system.  They are excellent for use with sludge, slurries and other viscous fluids.  Both styles provide a streamlined path for fluid flow that yields minimal pressure drop across the valve.

The flow transfer and control category covers a wide spectrum of products designed to facilitate, control, maintain, meter, or read the flow of material through hoses, pipes or tubing. The material in question can be liquid, gaseous, or semi-solid (colloids and slurries). The following families fall within this category: valves, valve actuators and positioners, dispensing valves, pumps, flow sensing, level sensing, density and specific gravity sensing, viscosity sensing, and miscellaneous related products.

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