Bently Nevada 31000-16-05-00-036-03-00 Proximity Probe Housing Assembly – 3300 Series

Bently Nevada 31000-16-05-00-036-03-00: Eddy Current Probe Housing Assembly for Continuous Shaft Displacement Monitoring

The Bently Nevada 31000-16-05-00-036-03-00 is a factory-assembled proximity probe housing unit engineered for the 3300 Series continuous vibration monitoring platform. Its primary function within a machinery protection loop is to mechanically position a 5 mm eddy current probe tip at a fixed, repeatable standoff distance from a rotating shaft surface — typically between 0.25 mm and 2.54 mm (10 mil to 100 mil) — and to route the coaxial signal cable to the proximitor module without introducing impedance discontinuities or mechanical stress points that would corrupt the DC gap voltage output.

Unlike generic aftermarket housings that approximate OEM dimensions, the 31000-16-05-00-036-03-00 is machined to Bently Nevada factory tolerances. The M10 × 1.0 thread pitch, probe tip recess depth, and cable exit geometry are dimensionally identical to the original design specification. This eliminates the need for field shimming, gap recalibration, or bracket modification during replacement — a critical operational advantage during planned outages where instrument loop re-verification time is constrained.

The housing is constructed from 316L stainless steel, selected for its resistance to chloride-induced stress corrosion cracking, hydrogen sulfide (H₂S) attack, and process condensate in oil and gas environments. The integral 0.9 m (36 in) armored coaxial cable is factory-terminated at both ends — at the probe tip and at the coaxial connector — eliminating field-splice failure points that are a statistically significant source of false vibration trips in long-service installations.

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Technical Parameters

Hardware Logical Analysis

The 31000-16-05-00-036-03-00 operates on the principle of electromagnetic induction: the probe tip generates a high-frequency oscillating magnetic field (typically 1 MHz carrier) that induces eddy currents in the conductive shaft surface. The magnitude of these eddy currents — and therefore the energy absorbed from the oscillator circuit — varies inversely with the air gap between probe tip and shaft. The proximitor module converts this energy variation into a DC voltage output at 200 mV/mil sensitivity, which feeds the monitoring rack’s analog input channel.

EMC Design: The armored coaxial cable construction provides continuous 360° shielding from the probe tip to the connector. The shield is grounded at the proximitor end only (single-point grounding), preventing ground loop currents from appearing as low-frequency noise on the signal conductor. In high-EMI environments — such as variable frequency drive (VFD) motor rooms or switchgear rooms — this shielding architecture maintains signal-to-noise ratios sufficient for 1 mil (25 µm) measurement resolution.

Mechanical Stability: The M10 × 1.0 fine-pitch thread provides a 0.025 mm axial displacement per degree of rotation, enabling precise gap setting during installation. The jam nut locking mechanism, when torqued to specification (typically 14–20 N·m depending on bracket material), maintains probe position under continuous vibration loads up to 50 g peak acceleration — well above the API 670 requirement of 20 g for probe mounting hardware.

Thermal Compensation: The 316L SS housing has a coefficient of thermal expansion (CTE) of approximately 16 µm/m·°C. For a 100 mm probe body, a 100 °C temperature excursion produces approximately 0.16 mm of axial thermal growth. In high-temperature applications (bearing housings above 120 °C), this thermal offset must be accounted for in the initial gap setting — typically by setting the cold gap 0.1–0.2 mm tighter than the nominal operating gap specified in the system calibration sheet.

Cable Impedance Matching: The integral 0.9 m cable is impedance-matched to the 3300 XL extension cable system. The total system cable length (probe integral cable + extension cable) must match the proximitor calibration range. Mismatched cable lengths shift the linear range endpoint voltages and introduce a systematic measurement offset that cannot be corrected by zero adjustment alone — it requires full system recalibration per Bently Nevada procedure TN-13.

System Integration Benefits

• Drop-in OEM Replacement: Identical form, fit, and function to the factory-installed unit. No bracket modification, re-drilling, or cable rerouting required. Reduces planned outage instrument loop restoration time from hours to under 30 minutes per measurement point.
• API 670 Compliance Out of Box: Accepted by insurance underwriters, plant safety auditors, and third-party inspection bodies without supplementary documentation. Eliminates the compliance re-verification burden associated with non-OEM substitutes.
• Deterministic Signal Latency: The eddy current measurement chain (probe → extension cable → proximitor → rack monitor) has a signal propagation delay of less than 1 ms end-to-end. This deterministic latency is essential for machinery protection systems that must trip within 1–2 shaft revolutions of a dangerous vibration event.
• Diagnostic Transparency: The 200 mV/mil output is a linear, DC-coupled signal that can be trended over time using the 3500 Series rack’s built-in data logging. Gradual bearing wear manifests as a slow DC shift in the gap voltage — detectable weeks before vibration amplitude thresholds are reached, enabling condition-based maintenance scheduling.
• Multi-Plane Measurement Capability: A single bearing housing typically requires two probe assemblies mounted 90° apart (X and Y planes) for full radial vibration characterization. The 31000-16-05-00-036-03-00 is available in matched pairs with identical sensitivity calibration, ensuring balanced measurement accuracy across both planes.
• Compatibility with 3500 Series Rack: The 200 mV/mil output is directly compatible with the Bently Nevada 3500/40M and 3500/42M proximity monitor cards. No signal conditioning or range adjustment required at the rack input card.
• Reduced False Trip Risk: Factory-terminated cable connectors eliminate the field-splice failure mode — a leading cause of intermittent open-circuit faults that trigger false machinery trips. Each connector is tested for continuity and insulation resistance (>100 MΩ at 500 VDC) before shipment.
• Long-Term Spare Parts Availability: The 31000 series housing assembly has been in continuous production for over two decades. Stocking this part number ensures long-term maintainability for installations with 20–30 year design life requirements, without the risk of OEM discontinuation forcing a full probe system redesign.

Quality Assurance & Global Logistics

Every Bently Nevada 31000-16-05-00-036-03-00 unit supplied by siemensplc.com is sourced through verified distribution channels with full supply chain traceability. Incoming inspection includes dimensional verification of the M10 thread profile, coaxial cable continuity test, insulation resistance measurement (≥100 MΩ at 500 VDC), and connector seating force check. Units that fail any inspection criterion are quarantined and returned — they are not downgraded or sold as seconds.

A Certificate of Conformance (CoC) is available for every shipment upon request — standard practice for API 670 installations requiring material traceability documentation. Third-party inspection reports (SGS, Bureau Veritas) can be arranged for orders requiring independent verification.

Shipments originate from our warehouse in Xiamen, China. Standard export documentation is prepared for all international orders, including commercial invoice, packing list, and HS Code 9031.80 classification for customs clearance. Express courier options (DHL Express, FedEx International Priority) support shutdown-critical deliveries with transit times of 3–5 business days to most global destinations. Domestic China orders ship via SF Express with next-day delivery to major industrial cities.

All units are packaged in ESD-safe foam inserts within rigid outer cartons. The coaxial connector is capped with a protective dust cover for transit. Storage conditions in our climate-controlled warehouse (18–25 °C, RH <60%) ensure no moisture ingress or connector oxidation during inventory holding periods.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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