The Bently Nevada 21000-28-05-15-012-04-02, also cataloged as the 21000 series Proximity Probe Housing, operates as a dedicated hardware component for the mechanical positioning and environmental containment of eddy-current transducers within machine casing interfaces.

Model Configuration Matrix

The 21000-28-05-15-012-04-02 part number denotes a specific assembly configuration. The parameters specify a 1/2-20 UNF probe thread interface, a 1/2-inch NPT mounting thread, and a 12-inch (approximately 305 mm) housing length. This assembly is designed to facilitate the axial positioning of the transducer tip relative to a shaft surface, ensuring the gap distance remains stable during machine operation.

Hardware Specifications

Eddy-Current Transducer Performance

System accuracy in monitoring rotor dynamics relies on the mechanical stability of the housing assembly. The housing must be secured using the integrated jam nut to prevent vibration-induced signal drift. Precise gap voltage validation is required during installation; the transducer must be positioned to achieve the -10 VDC nominal gap voltage target to ensure the output signal operates within the calibrated linear range. Furthermore, cross-talk suppression must be considered by maintaining adequate distance between multiple probe installations to prevent electromagnetic interference from adjacent oscillators.

## Ordering info

• 1x 21000-28-05-15-012-04-02 Probe Housing Assembly

• 1x Lock nut and O-ring assembly

• 1x Technical installation documentation

Field Installation Guidelines

• Surface Preparation: Ensure the machine mounting boss is flat and tapped to a depth that permits at least 5 full thread engagements of the NPT mounting thread.

• Sealing: Apply an industry-approved thread sealant to the NPT threads to prevent lubricant leakage from the internal casing.

• Positioning: Thread the housing into the mounting boss and adjust axially until the probe tip achieves the required -10 VDC gap voltage relative to the shaft surface.

• Securing: Tighten the jam nut to a torque of 5.1 N-m (45 in-lb) to fix the housing position and prevent mechanical movement during rotation.

Frequently Asked Questions

• Is this housing compatible with non-Bently probes? The housing is designed for standard probe thread dimensions; however, compatibility with third-party probe geometry is not verified.

• What is the purpose of the 12-inch length? This dimension is provided for applications where the machine casing wall is thick or requires a recessed mounting position for the probe.

• Can this housing be used in high-pressure oil zones? Yes, provided the NPT threads are sealed correctly and the O-ring is inspected for integrity to prevent fluid ingress.

• Does this housing affect the probe sensitivity? No, the housing is a passive mechanical component; it does not alter the electromagnetic characteristics of the probe.

• Can the jam nut be reused after disassembly? Yes, if the threads remain intact and are free from debris or deformation.

• What if the probe does not reach the target? Ensure the housing is threaded deeply enough into the mounting boss or verify the machine casing thickness.

• Why is the O-ring important? The O-ring acts as the primary seal between the machine interior and the external environment to contain process fluids or lubricants.

• Can I replace the O-ring with a generic substitute? It is recommended to use the factory-supplied O-ring to ensure proper material compatibility with industrial lubricants.