Product Overview

The Bently Nevada 21000-33-05-00-035-03-02 represents a critical mechanical interface component within the broader suite of Turbine Supervisory Instrumentation (TSI). As a high-precision proximity probe housing assembly, it serves as the physical conduit and protective environment for eddy-current transducers monitoring rotor dynamics. Engineered for industrial turbomachinery, this assembly ensures the rigid positioning of the probe relative to the machine shaft, a necessity for maintaining accurate vibration and displacement data. By decoupling the transducer from structural machine noise, the housing assembly stabilizes the critical gap distance, which is fundamental to the linear operation of the proximity sensing system.

Technical Specifications

Model Configuration Explanation

The 21000-33-05-00-035-03-02 model number is structured to communicate specific mechanical dimensions and interface requirements:

• 21000: The core series identifier for Bently Nevada probe housings.

• 33: Specifies the probe diameter compatibility (11 mm probe series).

• 05: Mounting thread specification (standard 3/4-14 NPT).

• 00: Extension piece configuration (no intermediate extension required).

• 035: Overall housing length of 350 mm, providing the necessary reach for deep-set machine ports.

• 03: Conduit fitting type, designed for standard industrial conduit interfaces.

• 02: Material and protective coating option, ensuring chemical and thermal resistance in aggressive lubrication environments.

Typical Applications

The 21000-33-05-00-035-03-02 assembly is deployed in environments where precise non-contact displacement measurement is paramount:

• Steam and Gas Turbines: Monitoring radial vibration at bearing locations to prevent catastrophic mechanical failure.

• Centrifugal Compressors: Providing shaft centerline position data to ensure alignment within bearing clearances.

• Hydroelectric Generators: Utilizing the deep-reach 350 mm profile to clear turbine casing thickness.

• Critical Balance of Plant Equipment: Where environmental sealing of the transducer cable is required to protect against oil mist and moisture ingress.

System Compatibility

This housing is explicitly designed to support Bently Nevada’s 11 mm proximity probe family. It ensures full mechanical compatibility with 3300 XL and legacy 11 mm probe systems. While the housing is passive, its structural integrity is vital for the Proximitor sensor to receive an interference-free signal. Users should ensure that the probe internal threads align with the specific 11 mm probe tip geometry to avoid mechanical binding during the gap-setting phase.

Installation Guidelines

Proper mounting of the 21000-33-05-00-035-03-02 is essential for signal integrity:

• Ensure all threads are clean and free of metal shavings before installation.

• Use a high-quality thread sealant compatible with the operating temperature of the machine casing.

• Thread the assembly into the machine port until the desired depth is reached, ensuring the housing remains perpendicular to the shaft centerline.

• Secure the housing using the supplied jam nuts to prevent vibration-induced migration.

• Route the probe cable through the conduit fitting, ensuring a minimum bend radius is maintained to protect the coaxial cable’s internal dielectric.

• Verify electrical ground continuity between the housing assembly and the machine chassis to maintain effective EMI/RFI shielding.

Product Advantages

• Precision Geometry: Minimizes mechanical resonance, providing a cleaner vibration signature for diagnostic systems.

• Material Resilience: Stainless steel construction resists oxidation, making it ideal for continuous service in high-heat lubrication zones.

• Standardized Interface: Simplifies spare parts management by adhering to industry-standard NPT mounting dimensions.

• Environmental Sealing: Designed to prevent oil migration, protecting the internal cable pathways from contamination.

Ordering Information

The 21000-3305-00-035-03-02 package typically includes:

• One (1) 350 mm stainless steel housing body.

• Factory-installed jam nuts and mounting hardware.

• O-ring seal kit for pressure-tight applications.

• Installation technical manual.

• Note: Confirm site requirements for conduit compatibility before selecting the specific housing length.

Frequently Asked Questions

• Can this housing be used with 8 mm probes?

  No. This housing is specifically machined for the 11 mm (Suffix 33) probe diameter. Using an 8 mm probe will result in a loose fit and incorrect gap measurements.

• Does the length (350 mm) include the conduit fitting?

  The 350 mm designation refers to the total length of the housing assembly from the mounting flange to the conduit interface, providing the reach needed for thick machine walls.

• What sealant should be used for high-temperature applications?

  Always use a thread sealant rated for at least 177 deg C, such as a high-grade PTFE paste or tape suitable for turbine oil environments.

• Is the 21000 series housing pressure-rated?

  Yes, when installed with appropriate thread sealants, this assembly is designed to maintain a seal against the internal pressures found in standard bearing housings.

• How do I prevent mechanical resonance?

  Ensure the housing is threaded deeply into the machine port to minimize the exposed lever arm. A "bottomed-out" or rigidly locked installation reduces vibration-induced noise.

• What material is the housing made of?

  The 21000-33-05-00-035-03-02 is constructed from high-grade stainless steel to ensure longevity in chemically aggressive and hot environments.

• Can I replace the conduit fitting if it breaks?

  The conduit fitting is integrated into the 21000 housing assembly design. If the fitting is damaged, the entire housing assembly should be replaced to ensure seal integrity.

• How does this housing protect the probe cable?

  The housing assembly allows for the attachment of rigid or flexible conduit, which shields the sensitive coaxial cable from physical impact, abrasion, and oil mist.