The WIKA BNA is a magnetic bypass level indicator designed for continuous liquid level monitoring in tanks and vessels. A float with an integrated permanent magnet moves with the liquid level inside a bypass chamber connected to the vessel. The magnetic field rotates the external display elements, providing a clear visual indication without direct contact between the process liquid and the display.
With configurable chamber materials, process connections and optional level measurement accessories, the BNA can be adapted to a wide range of industrial operating conditions.
Key Features
- Power-free level indication: Displays liquid level without an external power supply.
- Continuous visual monitoring: Magnetic rollers or stainless steel flaps indicate the liquid level.
- Robust bypass design: Suitable for demanding industrial process environments.
- Wide operating limits: Configurations available for temperatures from -196°C to +450°C and pressures from vacuum to 400 bar.
- Flexible materials: Multiple chamber and connection materials are available for different media.
- Optional instrumentation: Can be equipped with level transmitters and magnetic switches.
- Customized configurations: Process connections, chamber dimensions and accessories can be selected to meet application requirements.
- Hazardous-area options: Explosion-protected versions are available for selected configurations.
Suitable Applications
- Chemical & Petrochemical Processing
- Oil & Gas Production
- Power Plants & Power Generation
- Shipbuilding & Offshore Installations
- Water & Wastewater Treatment
- Food & Beverage Processing
- Pharmaceutical Manufacturing
- Industrial Tanks & Process Vessels
Verify material compatibility, hygiene requirements and applicable approvals for the intended application.
How It Works
- Liquid level follows the vessel: The bypass chamber connects to the tank through at least two process connections.
- Magnetic float moves: A float inside the chamber rises or falls with the liquid level.
- External display responds: The float's magnetic field rotates the display elements through the chamber wall.
- Level is visible at a glance: The two-color display changes from white to red as the level rises and from red to white as it falls.
Technical Highlights & Selection Considerations
- Operating Pressure & Temperature: Confirm that the selected configuration meets the actual process conditions.
- Process Medium: Check liquid density and chemical compatibility with the float, chamber, seals and other wetted components.
- Chamber Material: Select suitable stainless steel, alloy or other available materials according to corrosion and process requirements.
- Process Connections: Confirm flange standards, thread types, connection sizes and center-to-center dimensions.
- Measuring Height: Specify the required level measurement range and vessel connection positions.
- Optional Transmitter: Add a compatible level transmitter when remote continuous measurement is required.
- Magnetic Switches: Specify switching points and contact requirements if level alarms or control functions are needed.
- Hazardous-Area Approvals: Confirm the required explosion protection and relevant certification for the installation site.
Frequently Asked Questions (FAQ)
Q1: What is the WIKA BNA used for?
The BNA is used for continuous visual indication of liquid levels in tanks and vessels across a wide range of industrial applications.
Q2: Does the BNA require electrical power?
No. Its magnetic display operates without an external power supply. Optional transmitters or switches may require electrical connections.
Q3: How does the magnetic display work?
A magnetic float follows the liquid level inside the bypass chamber. Its magnetic field rotates the external display elements to indicate the liquid level through the chamber wall.
Q4: What pressure and temperature limits are available?
Depending on the configuration, operating temperatures range from -196°C to +450°C, with pressure ratings from vacuum to 400 bar. Confirm the allowable limits for the selected design.
Q5: Can the BNA provide an electrical output?
Yes. Compatible level transmitters and magnetic switches can be installed as options for remote measurement, monitoring and level alarms.
Q6: What information is required for a quotation?
Provide the required measuring height, operating pressure and temperature, liquid density, process medium, chamber material, process connections, optional transmitter or switch requirements, and any hazardous-area approvals.
