Industrial valves · Мембранные разделители WIKA: конструкция, принцип действия и области применения
WIKA Diaphragm Seals: Engineering Guide to Protecting Measuring Instruments
A WIKA diaphragm seal is a barrier system designed to isolate sensitive measuring instruments — pressure gauges, sensors, and pressure switches — from direct contact with process media that can be aggressive, viscous, crystallizing, abrasive, or have extreme temperatures (from –90 °C to +400 °C). EV Group China supplies these engineering solutions to ensure the durability and accuracy of instrumentation systems in the most challenging industrial conditions.
Principle of Operation and Design
The separator's operation is based on hydraulic pressure transmission. The system is hermetically sealed with a special fluid (e.g., silicone oil or glycerin). The pressure of the process acts on a flexible separating diaphragm. This diaphragm, by deflecting, transmits force through the filling fluid to the instrument's measuring element (Bourdon tube, strain gauge, etc.). Thus, the measuring mechanism is completely isolated from the working medium, but accurately registers its pressure.
Key Tasks Solved by Diaphragm Seals
- Protection against corrosion and clogging: Complete isolation of the measuring mechanism from chemically active or solid-particle-containing media, which prevents its destruction and blockage.
- Maintaining measurement accuracy: Correct pressure transmission through an inert filling fluid without distortion of metrological characteristics.
- Damping hydraulic shocks: The system smooths out sudden pressure fluctuations (pulsations), significantly extending the service life of measuring equipment.
- Simplified maintenance: The ability to dismantle and calibrate a pressure gauge or sensor without stopping the process and breaking the system's hermetic seal.
Technical Parameters and Materials
The choice of materials and design of the separator directly depends on the parameters of the process. High-strength and corrosion-resistant alloys such as AISI 316L stainless steel, Hastelloy C276, titanium, and Monel are used for manufacturing, which guarantees durability in the harshest operating conditions.
| Parameter | Value |
|---|---|
| Operating pressure | up to 400 bar (depends on model) |
| Medium temperature | –40... +400 °C |
| Diaphragm materials | AISI 316L, Hastelloy C-276, titanium, Monel |
| Filling fluid type | silicone, glycerin, fluorocarbon, mineral oil |
| Connection type | flanged, threaded, hygienic, capillary |
| Compatible instruments | WIKA pressure gauges, transmitters, pressure switches |
Design Options
- Threaded: A compact solution for quick installation into standard ports (G and NPT thread types). Optimal for general industrial applications.
- Flanged: The most reliable option for critical pipeline sections with high pressure and dynamic loads. Compliant with EN and ASME standards.
- Aseptic/Sanitary: Specialized designs for pharmaceutical and food industries (TRI-CLAMP, VARINLINE standards), eliminating dead zones and ensuring sterility.
- Special: Reinforced models for working with abrasive media and at ultra-high temperatures up to +450 °C, often equipped with additional cooling elements.
Where We Apply
WIKA diaphragm seals are indispensable in industries where measurement accuracy and reliability are critical:
- Oil & Gas and Chemical Industry: Pressure measurement in reactors, columns, and pipelines transporting acids, alkalis, suspensions, and polymerizing substances.
- Food and Pharmaceutical Industry: Pressure control in homogenizers, bioreactors, filling lines, and CIP/SIP systems. Hygienic designs ensure compliance with 3-A and EHEDG standards.
- Energy: Monitoring of superheated steam pressure in boilers, turbine oil systems, and cooling circuits.
- Pulp and Paper Industry: Working with sludge, adhesives, and other viscous and fouling media.
What to Replace With / Analogues
When choosing an alternative to WIKA diaphragm seals, the key factor is not the brand, but the complete compliance of the technical characteristics with the process requirements. Similar functional devices are offered by manufacturers such as Endress+Hauser, VEGA, or Trafag. When selecting an analogue, the engineer or purchaser should pay primary attention to the following parameters:
- Diaphragm material: It must be absolutely inert to the measured medium. Use chemical compatibility tables for verification (e.g., Hastelloy C-276 for chlorides, tantalum for hot acids).
- Filling fluid type: Its temperature range and food grade approval (if required) must correspond to the process.
- Connection design and standard: Flange, thread, or hygienic clamp must perfectly match the mating part on the equipment.
What to Clarify with the Supplier
To ensure the reliability and compliance of the measurement assembly, before purchasing a batch of diaphragm seals from a supplier such as EV Group China, it is recommended to request the following set of documents and data:
- Material Certificate (EN 10204-3.1): A document confirming the chemical composition of the diaphragm and housing alloy.
- Factory Test Protocol: At a minimum, a report on the leak tightness test (helium leak detector) and calibration of the assembled unit (diaphragm seal + instrument).
- Filling fluid information: Exact name, manufacturer, and confirmation that it is compatible with the process temperature regime and is non-toxic (for food applications).
- Traceability data: Batch number, allowing tracking of the entire component production chain.