Overview
The Magnetrol B73-1B20-CDG is a sealed external cage liquid level switch engineered for side mounting to tanks and pressure vessels. This self-contained unit is designed for side mounting to a tank or vessel with threaded, socket weld or flanged pipe connections, and features float-actuated controls that have proven their reliability in process control for decades. The dry contact (CDG) switch mechanism makes this model suitable for electrical relay circuits and remote monitoring systems.
Key Features
- Permanent magnet attached to a pivoted switch actuator; as the float/displacer rises following the liquid level, it raises the attraction sleeve into the field of the magnet, which then snaps against the non-magnetic enclosing tube, actuating the switch.
- The enclosing tube provides a static pressure boundary between the switch mechanism and the process.
- Dry contact output for compatibility with PLC, relay logic, and SCADA systems
- ISO 9001 certified quality assurance system approved for design, construction and service
- 360° rotatable housing for flexible field installation
- Factory Mutual listed for safety-critical applications
Technical Specifications
- Model: B73-1B20-CDG
- Series: B73 External Cage
- Float Chamber Material: Carbon Steel (per -1 designation)
- Pipe Connection: 1″ NPT (per -B20 designation)
- Switch Type: Dry Contact (CDG mechanism)
- Float Type: External cage magnetic float
- Mounting Orientation: Within 3° of vertical (all directions)
- Enclosure Rating: TYPE 4X/7/9 available (polymer coated aluminum) or NEMA 1 carbon steel options
- Certifications: Factory Mutual (FM), ISO 9001, EN 61010-1
- Housing Rotation: 360° rotatable
- Warranty: Five years from factory shipment (mechanical defects in materials and workmanship)
Typical Applications
- Tank fill/empty level detection and alarm
- Process vessel overflow protection
- Pump start/stop automation (high/low level control)
- Liquid storage tank monitoring for petrochemical, refining, and chemical processing industries
- Boiler feedwater level control
- Pneumatic system reservoir level control
- Industrial safety systems requiring Factory Mutual certification
Compatibility & Replacements
Compatible With
- PLC input modules (24 VDC dry contact compatible)
- Relay logic control circuits
- SCADA systems with discrete input cards
- Pneumatic control systems (via dry contact relay)
- Tanks and vessels with 1″ NPT side-mount connections
- Industrial automation controllers requiring mechanical level sensing
Replaces / Drop-In Replacement For
- Magnetrol B73-1B20 models with different switch mechanisms (consult specific application requirements)
- Other Magnetrol B73 external cage switches with equivalent NPT connections and carbon steel construction
- Legacy float-type level switches requiring dry contact output in similar tank mounting configurations
Works With
- Dry contact relay circuits and logical switching networks
- 24 VDC industrial control power supplies
- AC/DC solenoid valve coils via relay interface
- PLC discrete input modules (Allen-Bradley, Siemens, Mitsubishi, Omron, etc.)
- Factory Mutual-certified safety instrumented systems (SIS)
- Industrial communication protocols (via upstream relay conversion hardware)
