Sanitary single seated valves are a type of globe valves used to shut off or change the direction of fluid flow in high-pressure applications. They are preferred because of their simple design: a movable disc-type element with unique designed seat is maneuvered to seal the port on well treated body. Single seated valves as the name suggest only feature one seat.
Single seated valves have a unique designed seat in plug that can be manipulated into open or closed position using a plug-headed stem. The plug can also be called a disk or disc.
Single seat valves feature a simple design with few internal parts hence more stability and less mass as compared to double seat valves. With the simple perpendicular motion of the stem towards or away from the seat, you can shut off or open the port allowing for the fluid to flow.
The distance between the valve plug and the valve seat when the port is open determines the rate of flow of the fluid.
Uses of Sanitary Single Seated Valves
As shut off or stop valves, they are used as on/off systems to halt or allow the flow of the fluid. They provide a simple yet pressure-tight and durable seal using very few internal parts.
As divert valves, the single seat valves are used to provide precise and excellent throttle in high-pressure systems to change the direction of fluid flow. Single seat valves used in fluid diversion have got a modular design to allow for any possible configuration that achieves the desired product flow.
Operation of Single Seated Valves
Manual maneuver
In the case of manual maneuver, the stem/seal and the body feature thread that wedge between each other when the stem is rotated by the hand. The stem will feature a handle that is turned to produce the vertical movement of the plug towards or away from the valve body.
Automatic Maneuver
In automatic maneuver, the stem is smooth and manipulates the valve position by gliding through the body. The valve will feature remote-controlled or self-activating solenoid and pneumatic actuators.
Features and Technical Specifications of Singe Seated Sanitary Valves
Single seated sanitary valves are designed to be used in applications requiring hygienic and sterile applications. They are made to deliver millions of cycles in high pressure and extreme temperature range operations. Single seated valves used in sanitary applications have been certified to carry 3-A rating and symbol.
The bodies and plugs used in sealing the valve are uniquely designed to eliminate dead angle and prevent entrapment of fluids. Bonnet design can be screw-in, bolted, or union. The screw-in bonnet is suitable for leakproof pressure-tight sealing while the union bonnet allows for easier inspection of the valve.
The sealing materials used are also elastic to help with water-hammer effects. Elastic compressions allow the seal to absorb some of the shocks from the fluid when the valve gets suddenly shut.
In addition to the no-dead angle design and elasticity, the sealing material is frictionless to eliminate noise during valve operations and both durable and extreme temperature resistant to support several cycle vacuum operations at high or low temperatures.
Sanitary single seat valves are available in flexible body combinations too but feature very few internal parts that allow for easier maintenance operations. They are preferred because they are smaller and lighter but capable of excellent shut off capability as compared to double seated valves.
Why Use Sanitary Single Seated Valves
Sanitary single seated valves are simple, with very few internal parts that allow for easier maintenance operations. To get to the valve components, you just have to dislodge the bonnets off. Few internal parts enhance the stability of the valve against the fluid pressure.
Single seated valves are also smaller and lighter but with excellent shut off capability as compared to double seated valves. They do not add to the mass of the pipes or fluid container. The reduced mass also reduces vibration and noise during plug operations.
The single seated valve comes in an assortment of trim configurations to allow for the flow characteristic you want. As aforementioned, you can get the angle design, the Y-body, or the Z-body.
Depending on your sanitation requirement, you can get single seated valves from DN25/1’’— DN100/4’’ in size with intelligent controllers and indicators to show the state of the port — closed or open. This could be position sensors, pressure sensors with AISI 316L wetted parts to regulate the valve’s opening range. Single seated valves are also available in FDA approved FPM Viton gaskets to prevent leakages and enable sterile processes.
The only con of single seated valves is that very complex valve designs are required if you have to balance high-pressure systems, but otherwise single seated valves designs are modular and hygienic to support a wide variety of sanitary application.
Configurations of Pneumatic Single Seat Valves
Depending on the application you want to carry out, you can get sanitary single seat valves with the following options:
- Sizes DN25/1” – DN100/4”.
- EPDM, Silicone or FPM made gaskets in compliance with FDA 177.2600
- DIN, RJT, IDF or SMS end connections.
- Steam barrier (if shaft sterilization is required)
- Body jacket insulation.
- Ra 20μin (0.5μm) for internal surface finish.
- The change-over single seat valve is also available and allows for switching between Normally Open and Normally Closed by rotating the cylinder 180°.
- External proximity sensor
Other configurations include extra intelligent controllers and indicators to show the state of the port – closed or open. This could be position sensors, pressure sensors with AISI or 316L wetted parts to regulate the valve’s opening range. The IL-TOP unit, for example, is an intelligent control module that allows you to set a value that will be used to position the valve as open or closed when specific logics are met.
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