Equipment Process Principle Of Sanitary Diaphragm Valve
A sanitary diaphragm valve controls process flow through movement of a flexible diaphragm. The diaphragm lifts from the weir to open the passage and presses against it to close the flow. At the same time, it separates the process medium from the stem and actuator, creating a sealed flow path.
How the Valve Process Works
The operating principle is based on diaphragm movement. When the actuator moves the stem, the diaphragm changes position and controls the opening.
- Opening: The diaphragm lifts from the weir.
- Flow: Fluid passes through the valve body.
- Closing: The diaphragm moves toward the weir.
- Sealing: The diaphragm closes the passage and isolates the medium.
Main Components
A typical valve contains:
- Valve body: Forms the process flow passage.
- Diaphragm: Provides sealing and process isolation.
- Stem: Transfers actuator movement.
- Bonnet: Supports the operating assembly.
- Actuator: Provides manual or pneumatic movement.
Diaphragm and Body Interaction
The diaphragm performs two functions. It closes the flow passage against the weir and separates the process fluid from the operating mechanism.
Hygienic diaphragm valves commonly use SS316L wetted components with EPDM or PTFE-based diaphragms. Some configurations are rated up to 10 bar, with temperatures reaching about 150°C depending on diaphragm material.
Flow Path and Hygienic Performance
The internal body shape affects flow, drainage, and cleaning. Weir-type construction limits retention around the sealing area, while smooth internal surfaces reduce locations where residue can collect.
Aseptic diaphragm valves can use polished or electropolished surfaces for applications requiring controlled surface conditions. Some specifications reach Ra ≤0.4 μm.
Process Configurations
Different body designs provide different flow arrangements:
- Two-way: Controls flow between inlet and outlet.
- Three-way: Diverts or combines flow paths.
- U-type: Supports drainage and vessel outlet service.
- Tank-bottom: Connects to a vessel outlet with reduced product retention.
A sanitary solenoid valve can also be incorporated into automated systems to control a pneumatic diaphragm valve through electrical signals.
Typical Specifications
| Parameter | Typical Specification |
|---|---|
| Body material | SS316L |
| Working pressure | Up to 10 bar |
| Diaphragm | EPDM / PTFE-EPDM |
| Connection | Clamp / Weld / Flange |
| Size | 1/2"–2" |
| Metric range | DN10–DN50 |
| Internal finish | Ra <0.8 μm |
| Operation | Manual / Pneumatic |
| Maximum temperature | About 150°C* |
*Actual limits depend on diaphragm material and operating conditions.
Where the Process Principle Is Applied
A sanitary diaphragm valve is used in pharmaceutical, biotechnology, food, dairy, beverage, and clean-fluid systems. Its diaphragm sealing method suits processes requiring controlled flow, process isolation, and cleanable internal passages.
The process principle is direct: actuator movement changes diaphragm position, diaphragm movement controls flow, and diaphragm sealing separates the process medium from the operating mechanism.
