Configured for mechanical protection and alignment of eddy-current sensors in rotating machinery, the Bently Nevada 21000-16-05-15-084-03-02 (21000 Probe Housing Assembly) provides direct physical housing for 3300 XL 8mm proximity probes. The assembly ensures stable sensor positioning to facilitate accurate clearance and vibration measurement.

Suffix Breakdown and Configuration Matrix

• Part Number: 21000-16-05-15-084-03-02

• Probe Type: 16 - 3300 XL 8 mm

• Cable Length: 05 - 0.5 m (20 in)

• Minimum Housing Length: 15 - 1.5 in (38 mm)

• Fitting/Seal: 03 - One 3/4-14 NPT plug, one 3/4-14 to 1/2-14 NPT reducer, and cable seal grip

• Thread Specification: 02 - 3/4-14 NPT

Hardware Specifications

Mechanical Monitoring and Probe Dynamics

The integrity of proximity probe data depends on rigid mounting to minimize mechanical resonance and signal noise. For correct eddy-current probe scaling, the probe tip must be installed within the housing to ensure a linear output characteristic. During setup, installers must perform gap voltage validation to ensure a -10 VDC target (or specific calibration curve range) is achieved relative to the target surface. Proper assembly of the cable seal grip is required to achieve cross-talk suppression and prevent moisture ingress, which can interfere with the transducer’s high-frequency carrier signal and subsequent rotor dynamics data.

Ordering Info

• 1 21000 Series Probe Housing Assembly

• 1 3/4-14 NPT plug

• 1 3/4-14 to 1/2-14 NPT reducer

• 1 Cable seal grip set (includes grommets for 1/8 to 3/16 inch, 1/4 to 5/16 inch, and 5/16 to 3/8 inch cable diameters)

Field Installation Guidelines

• Housing Alignment: Thread the housing into the machine casing to the required depth to achieve the probe’s linear operating range.

• Seal Security: Select the correct grommet size based on the probe cable diameter to ensure a liquid-tight seal at the cable grip.

• Locking: Utilize the provided NPT plugs and reducers to seal unused ports, maintaining the environmental integrity of the housing assembly.

• Shielding: Ensure the cable shield is terminated according to site grounding practices to minimize electrical interference.

Frequently Asked Questions

• What is the purpose of the 3/4-14 NPT reducer?

  The reducer allows for adaptation of the housing assembly to smaller 1/2-14 NPT conduit or instrumentation ports commonly found in machinery casing setups.

• How is the probe depth adjusted?

  Probe depth is adjusted by threading the probe assembly within the housing. Once the correct gap is set, the lock nut must be tightened to prevent movement due to vibration.

• Does this housing support other probe diameters?

  This model is specifically configured for 8 mm 3300 XL probes. Use with other probe types may result in improper fitment and loss of sensing accuracy.

• Can I use Teflon tape on the NPT threads?

  Yes, PTFE (Teflon) tape is recommended for NPT threads to ensure a pressure-tight seal and prevent oxidation in the thread interface.

• How do I verify the probe gap?

  The gap is verified using a feeler gauge between the probe tip and the target surface, confirming the voltage output matches the sensor’s calibration curve.

• Is the housing assembly pressure rated?

  The assembly is designed for standard machinery environments. For high-pressure applications, ensure the NPT connection is rated for the specific process pressure.

• What happens if the cable seal is not tightened?

  Failure to tighten the cable seal allows oil or process fluids to travel along the cable, which can degrade the insulation and cause erroneous signal readings.

• Does this assembly include a proximity probe?

  Yes, the model code specifies the inclusion of a 3300 XL 8 mm proximity probe within the housing assembly package.