Diaphragm Valve Detailed Overview

Types of diaphragm valvesDiaphragm valves come in two main types: weir diaphragm valves and straight/full port diaphragm valves.Weir diaphragm valvesWeir diaphragm valves have a distinctive raised ridge or weir in the center of the valve body, against which the diaphragm seals to regulate or stop flow.Weir design minimizes the diaphragm's travel distance to achieve a full seal, reducing stress and material wear, making it particularly effective for managing both low and high flow rates.The weir-type design, being the most popular, is especially suited for throttling applications and fluid flow control at low flow rates.It employs a two-piece compressor system for precise flow regulation, with the inner compressor lifting a central portion of the diaphragm in the initial stem travel phases. This design not only extends the diaphragm's life by requiring less material but also makes the diaphragm valve suitable for vacuum and high-pressure applications.Weir diaphragm valves are recommended for handling gasses, clean and homogeneous liquids, and even corrosive, hazardous, and abrasive media. However, they may experience increased pressure drops across the valve and are prone to sediment build-up and gumming from viscous liquids on either side of the saddle.Bonnet assemblies in these valves ensure safety by preventing fluid release if the diaphragm fails, and their self-draining feature makes them ideal for food processing applications.Full port diaphragm valvesFull port or straight-through diaphragm valves have a flat-bottomed valve seat, allowing fluid to flow in a straight path with minimal obstruction.Straight-through design is characterized by a lower pressure drop compared to weir valves, making it better suited for high-flow rate applications.The diaphragm in these valves must be highly flexible to seal against the flat bottom, which subjects it to more wear and tear, necessitating more frequent replacements.Straight-through valves excel in handling semi-solid media like slurries, sludges, and viscous fluids, thanks to their unobstructed flow path.They are also advantageous for bi-directional flow applications, as there are no saddles to impede flow reversal.