Bently Nevada 3300 XL Reverse Mount Probes

Technical Dossier

Product Details And Specifications

Bently Nevada 3300 XL Reverse Mount Probe Series Technical Notes

The Bently Nevada 3300 XL Reverse Mount Probe series, anchored by the 330705 part family, is a purpose-engineered eddy-current proximity sensing system designed for continuous shaft vibration and position monitoring in rotating machinery. Deployed across global heavy industry — including petrochemical complexes, nuclear power stations, offshore platforms, and crude oil refineries — the 3300 XL system forms the sensing front-end of Bently Nevada's 3300 Series monitoring infrastructure. These probes are installed in reverse-mount configurations where standard radial access is mechanically restricted, making them a critical component in turbine bearing housings, compressor casings, and pump pedestals operating under API 670 compliance requirements.

The 330705 probe is a 3/8-inch (8 mm) diameter eddy-current probe designed to operate with the 330180 extension cable and 330130 proximitor sensor. It is available in multiple cable lengths and connector configurations, covering both standard and intrinsically safe (IS) installations. The system outputs a linear DC voltage proportional to the gap between probe tip and conductive target, with a nominal sensitivity of 200 mV/mil (7.87 V/mm).

The Evolution of 3300 XL Reverse Mount Probe Architecture

Bently Nevada's eddy-current proximity probe technology traces its commercial origin to the 1960s, when the company standardized the 7200 Series as the industry's first widely adopted non-contact vibration sensing platform. The 3300 Series was introduced in the 1980s as a second-generation system with improved EMI shielding, tighter linearity tolerances, and a modular cable-proximitor architecture that separated the sensing element from the signal conditioning electronics.

The 3300 XL designation marks the third-generation refinement of this platform, introduced in the mid-1990s. Key architectural changes included: a revised probe-tip geometry for improved gap linearity across a wider temperature range (-35°C to +177°C continuous), a reinforced armored cable jacket rated for high-vibration environments, and a standardized 5-pin MIL-spec connector interface compatible with both the 330130 and 330180 signal conditioning chain. The reverse-mount variant (330705) was developed specifically to address installation constraints in back-to-back bearing configurations common in multi-stage centrifugal compressors.

3300 XL Reverse Mount Probe Full Catalog & Functionalities (SKU List)

Proximity Probes — 330705 Reverse Mount Family

• 330705-02-18-90-02-CN: 3/8 in. reverse mount probe, 18-inch cable, standard connector, metric gap
• 330705-02-12-90-02-CN: 3/8 in. reverse mount probe, 12-inch cable, standard connector, metric gap
• 330705-02-24-90-02-CN: 3/8 in. reverse mount probe, 24-inch cable, standard connector, metric gap
• 330705-02-36-90-02-CN: 3/8 in. reverse mount probe, 36-inch cable, standard connector, metric gap
• 330705-02-48-90-02-CN: 3/8 in. reverse mount probe, 48-inch cable, standard connector, metric gap
• 330705-02-18-90-02-00: 3/8 in. reverse mount probe, 18-inch cable, flying-lead termination
• 330705-02-12-90-02-00: 3/8 in. reverse mount probe, 12-inch cable, flying-lead termination

Extension Cables — 330180 Series (Compatible)

• 330180-51-05: 5-meter armored extension cable, standard temperature rating
• 330180-51-10: 10-meter armored extension cable, standard temperature rating
• 330180-51-15: 15-meter armored extension cable, standard temperature rating
• 330180-51-20: 20-meter armored extension cable, standard temperature rating

Proximitor Sensors — 330130 Series (Signal Conditioning)

• 330130-040-00-00: 3300 XL 8mm proximitor, -24 VDC, standard output, DIN rail mount
• 330130-045-00-00: 3300 XL 8mm proximitor, -24 VDC, IS-rated, DIN rail mount
• 330130-080-00-00: 3300 XL 8mm proximitor, -24 VDC, extended temperature range

Mounting Hardware & Accessories

• 21747-02: Reverse mount probe holder, 3/8-28 UNF thread, stainless steel
• 02-262610-01: Probe tip protector cap, 3/8 in. series, field installation

Sourcing Hard-to-Find & Obsolete 3300 XL Reverse Mount Probe Parts

• Cross-reference matching for discontinued part numbers to current or equivalent alternatives
• Cable assembly fabrication to custom lengths for non-standard installations
• Calibration verification reports traceable to NIST standards upon request
• Emergency urgent RFQ handling for critical plant maintenance scenarios

For plants operating under API 670 4th Edition or 5th Edition compliance, DriveKNMS can supply documentation packages including material certificates and test records to support maintenance management system (MMS) requirements.

Quality Control for the 3300 XL Reverse Mount Probe Range

Each 330705-series probe processed through DriveKNMS undergoes a structured inspection and functional verification protocol:

• Dimensional inspection: Probe tip diameter, thread pitch (3/8-28 UNF), and body length verified against OEM drawings
• DC resistance check: Coil resistance measured at probe tip; acceptable range per Bently Nevada specification sheet 141536-01
• Gap-voltage linearity test: Probe mounted in calibration fixture with target material (AISI 4140 steel); output voltage recorded at 0.5 mm increments across the full linear range (0.25 mm to 2.25 mm nominal)
• Cable continuity and insulation resistance: Shield continuity, conductor resistance, and IR tested at 500 VDC per IEC 60228
• Connector interface inspection: Pin alignment, locking mechanism, and sealing integrity verified for CN-type connectors
• High-temperature soak (optional): Available for probes destined for installations above 150°C ambient; 4-hour soak at rated temperature with post-soak re-verification of gap-voltage output