Bently Nevada 31000-29-10-20-025-02-02 Proximity Probe Housing Assembly – 3300 XL Series

Bently Nevada 31000-29-10-20-025-02-02 – Eddy-Current Proximity Probe Housing Assembly for Rotating Machinery Protection

The Bently Nevada 31000-29-10-20-025-02-02 is an 8 mm eddy-current proximity probe housing assembly belonging to the 3300 XL / 3000 Series non-contact transducer platform. Its primary function within a machinery protection control loop is to provide a mechanically stable, thermally compensated mounting interface that positions the probe tip at a repeatable radial gap from the rotating shaft surface. The housing assembly — in conjunction with the extension cable and Proximitor® driver — forms a three-component measurement chain whose combined output is a DC voltage linearly proportional to the instantaneous air gap between probe tip and target material. This voltage signal feeds directly into Bently Nevada 3500 Series monitor cards, where it is processed for radial vibration amplitude, shaft centerline position, and eccentricity alarms in accordance with API 670 machinery protection requirements.

The part number suffix structure encodes the full mechanical and electrical configuration: probe tip diameter code 29 (8 mm), standard probe body length code 10, integral cable length code 20 (2.0 m), extension cable length code 025 (2.5 m total loop), connector type 02 (standard coaxial), and approval code 02 (CE / CSA / FM). This deterministic part number architecture eliminates ambiguity during spare parts procurement and ensures the replacement unit is electrically and mechanically identical to the installed baseline.

Real-time Stock & RFQ: [email protected] | WhatsApp: +86 18359268345

Technical Parameters

Hardware Logical Analysis

The 31000-29-10-20-025-02-02 operates on the principle of high-frequency eddy-current induction. The probe tip contains a wound coil driven by the Proximitor® oscillator at approximately 1.0 MHz. When the conductive shaft surface enters the electromagnetic field, eddy currents are induced, loading the coil and reducing its Q-factor. The Proximitor® demodulates this impedance change into a DC output voltage with a transfer function of −7.87 V/mm across the calibrated linear range.

EMC Architecture: The armored coaxial cable between probe and Proximitor® is a triaxial shielded construction — inner conductor carries the RF oscillator signal, the intermediate shield is driven at the same potential as the inner conductor (guard-driven topology) to eliminate cable capacitance loading, and the outer armor provides low-impedance ground return. This configuration suppresses common-mode interference from variable-frequency drives (VFDs), high-current bus bars, and RF transmitters typically present in turbomachinery enclosures, maintaining signal integrity at noise environments exceeding 10 V/m field strength.

Thermal Compensation: The 316L stainless steel housing has a coefficient of thermal expansion (CTE) of approximately 16 µm/m·°C. The probe coil former is manufactured from a matched-CTE ceramic composite, ensuring that dimensional changes in the housing do not alter the coil-to-tip geometry across the −40 °C to +177 °C operating envelope. This passive thermal compensation maintains sensitivity within ±1% of nominal across the full temperature range without active correction circuitry.

Mechanical Locking: The M10 × 1.0 mounting thread incorporates a dual-locknut arrangement. The inner locknut sets the precise probe gap (typically 1.0–1.27 mm per API 670 §6.3), while the outer locknut provides vibration-resistant retention. Torque specification is 5–7 N·m on the inner nut, preventing gap drift under continuous vibration loads up to 50 g peak.

Target Material Sensitivity: The eddy-current field penetration depth (skin depth δ) at 1 MHz in AISI 4140 steel is approximately 8 µm, confining the measurement to the shaft surface layer. This makes the system insensitive to subsurface material variations while remaining highly responsive to surface runout, scratches, and plating non-uniformities — all of which are captured as electrical runout and must be subtracted during slow-roll compensation per API 670 §6.8.

System Integration Benefits

• Direct API 670 Compliance: The 31000-29 probe system meets API 670 5th Edition requirements for proximity transducer systems used in turbomachinery protection, including sensitivity tolerance (±3%), temperature coefficient, and cable length specifications — eliminating the need for site-specific deviation documentation.
• Zero-Recalibration Replacement: Factory-calibrated sensitivity of 7.87 V/mm is matched to the 330180 Proximitor® driver. Replacing a failed probe with an identical 31000-29-10-20-025-02-02 requires only gap resetting — no monitor card rescaling or alarm setpoint adjustment.
• Deterministic Latency in the Measurement Chain: The Proximitor® demodulator introduces a signal group delay of <1 ms, ensuring that the 3500 Series monitor card receives vibration data within one scan cycle (<20 ms for 3500/42M at 1× per-revolution sampling). This determinism is critical for overspeed and high-vibration trip logic.
• Diagnostic Transparency via Gap Voltage: The DC gap voltage output provides a continuous, passive health indicator. A gap voltage outside the −2 VDC to −18 VDC linear window immediately flags probe misalignment, cable open-circuit, or Proximitor® failure — without requiring additional diagnostic hardware.
• Shaft Centerline Plot Capability: Paired with a second orthogonal probe at 90°, the 31000-29 assembly enables full shaft centerline position tracking. The 3500/42M monitor computes X-Y orbit plots and DC gap trends, providing bearing load distribution data for predictive maintenance scheduling.
• Hazardous Area Suitability: Approval code 02 covers CE, CSA, and FM certifications. The Proximitor® driver (330180) carries ATEX Zone 1 and IECEx approval when installed in the safe area with the probe in the hazardous zone — a common configuration in gas compressor trains and offshore platform applications.
• Backward Compatibility with Legacy 3000 Series Infrastructure: The 31000 series probe is electrically interchangeable with earlier 3000 Series installations. Existing extension cables (330130 Series) and Proximitor® sensors (3300 XL) require no modification, protecting capital investment in installed monitor racks.
• Reduced Outage Duration: The M10 threaded housing allows probe replacement without removing the machine casing. Access through the probe boss fitting, gap resetting with a feeler gauge, and locknut torquing can be completed in under 15 minutes per probe — significantly reducing planned maintenance window duration on multi-probe installations.
• Long-Term Signal Stability: Non-contact eddy-current technology produces no mechanical wear on the probe tip or shaft surface. Signal drift over a 5-year continuous service period is typically <0.5% of full-scale output, supporting extended calibration intervals and reducing lifecycle maintenance cost.

Quality Assurance & Global Logistics

Every Bently Nevada 31000-29-10-20-025-02-02 unit supplied by siemensplc.com is sourced through verified industrial distribution channels with full traceability to Baker Hughes / Bently Nevada manufacturing records. Pre-shipment inspection protocol includes: visual examination of housing, cable armor, and connector integrity; continuity and insulation resistance measurement on the coaxial cable assembly (>100 MΩ at 500 VDC); verification of part number label against physical configuration; and anti-static packaging with silica gel desiccant for long-term storage integrity.

Shipments originate from our warehouse in Xiamen, China. Standard in-stock orders are dispatched within 1–2 business days via DHL Express, FedEx International Priority, or UPS Worldwide Expedited — with typical transit times of 3–5 business days to Europe, North America, and Southeast Asia. For time-critical plant outage situations, same-day dispatch is available on confirmed stock. Export documentation — including commercial invoice, packing list, certificate of origin, and ECCN/EAR classification — is prepared in compliance with Chinese customs regulations and destination country import requirements. All units are covered by a 12-month warranty from the date of shipment against manufacturing defects.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
© 2026 siemensplc.com. All rights reserved.