Product Core Brief

• Model: 330905-00-25-02-CN
• Brand: Bently Nevada (Baker Hughes)
• Series: 3300 XL NSv Sensor System
• Core Function: Non-contact eddy current proximity probe designed for tight-space vibration and displacement monitoring on centrifugal compressors, pumps, and fans.
• Product Type: NSv (Near Surface Vibration) Eddy Current Probe
• Key Specs: 200 mV/mil Sensitivity | 0-10 kHz Bandwidth | Ex-Proof Certified
• Condition: New Surplus / OEM Original

Key Technical Specifications

• Sensor Type: 3300 XL NSv Proximity Probe
• Sensitivity: 7.87 mV/μm (200 mV/mil) ± 6.5%
• Frequency Response: 0 to 10 kHz
• Certifications: Ex-Proof (CN suffix indicates China Instrument Explosion-Proof Safety Supervision and Inspection Station certification)
• Typical Application: Centrifugal air compressors, small water pumps, motors, fans
• System Compatibility: Pairs with 3300 XL NSv Extension Cables (e.g., 5m or 7m) and 330980 Proximitor Transmitters
• Output Type: Voltage (Analog)
• Installation Type: Threaded Mount
• Operating Temperature: Standard ambient (verify specific datasheet for exact range)

Product Introduction

Engineered for applications where standard probe bodies cannot fit, the Bently Nevada 330905-00-25-02-CN is a specialized NSv (Near Surface Vibration) sensor. It is specifically designed to be installed in the extremely tight clearance areas typical of centrifugal air compressors and compact rotating equipment.

As part of the 3300 XL NSv system, this probe works in conjunction with NSv extension cables and 330980 Proximitor transmitters (or 990/991 vibration/displacement transmitters) to provide highly accurate, non-contact shaft vibration and axial displacement monitoring. The “-CN” suffix confirms it carries the necessary explosion-proof certifications for safe deployment in hazardous chemical and petrochemical environments.

QA & Testing SOP

NSv probes operate in harsh, confined environments. We verify electrical integrity and certification compliance before release.

1. Anti-Counterfeit & Visual Audit: We inspect the stainless steel housing for corrosion, verify the Bently Nevada laser etching, and check the connector for bent center pins or damaged threads.
2. Cable Continuity & Shield Test: We perform a low-resistance sweep on the coaxial core and verify the braided shield has zero breaks, ensuring EMI noise won’t corrupt the microvolt-level signals.
3. Sensitivity Validation: Using an OEM test rig, we verify the probe’s electrical characteristics match the 200 mV/mil sensitivity spec and confirm the linear range is free from dead zones.
4. Certification Verification: We validate the “-CN” Ex-proof documentation and markings to ensure compliance with hazardous area requirements.
5. ESD Safe Packaging: The internal coil assembly is sensitive to static discharge. We pack the probe in anti-static shielding with desiccant to prevent latent dielectric breakdown.

Installation Pitfalls & Guide

❗ System Length Matching: NSv probes require specific extension cables to maintain calibration. The total system length (probe + extension cable) must exactly match the 330980 Proximitor transmitter’s configured system length (e.g., 5m or 7m). Mismatched lengths will cause severe calibration errors.

❗ Tight-Space Gap Calibration: Because NSv probes are used in confined spaces, adjusting the gap can be difficult. Always use a multimeter to verify the exact DC voltage at the Proximitor output during installation. An incorrect gap pushes the sensor out of its linear range, causing clipped waveforms and false alarms.

❗ Single-Point Grounding: The coaxial shield must be grounded at the Proximitor transmitter end only. Grounding at both the probe and transmitter creates a ground loop that injects 50/60Hz hum directly into your vibration readings.

Replacement SOP:

1. Pre-Install: Record the existing gap voltage and alarm setpoints; place the machine in bypass/maintenance mode.
2. Removal: Disconnect the extension cable; unthread the old NSv probe from the bracket; clean the mounting hole carefully in the confined space.
3. Install: Thread the new 330905 probe into the bracket; connect the NSv extension cable; route away from high-EMI sources.
4. Power-On Test: Apply power to the Proximitor; adjust the probe gap until the output reads -10 VDC ± 0.2V; verify DCS vibration readings are stable before removing bypass.

Technical FAQ

What does the “-CN” suffix mean?
The “-CN” suffix indicates that the probe has obtained the explosion-proof safety certificate from the China Instrument Explosion-Proof Safety Supervision and Inspection Station. It is specifically designed for use in hazardous chemical and petrochemical environments requiring Ex-proof compliance.

What is the difference between NSv probes and standard 8mm probes?
Standard 8mm probes (like the 330105 series) have a larger body diameter and are designed for general radial vibration monitoring. NSv (Near Surface Vibration) probes have a specialized, compact form factor designed specifically to fit into the extremely tight clearance areas of centrifugal air compressors and similar compact machinery.

What transmitters or monitors is this probe compatible with?
This probe is part of the 3300 XL NSv system. It connects via an NSv extension cable to a 330980 Proximitor transmitter, or directly to 990/991 vibration and displacement transmitters. From there, the 4-20mA or buffered output can be sent to PLCs, DCS systems, or Bently 3500/1900 series monitors.

Can I use a standard 5m extension cable with this NSv probe?
You must use an extension cable specifically designated for the NSv system. The total system length (probe integrated length + extension cable) must match the Proximitor transmitter’s configuration. Always verify the exact part number of the extension cable against your existing system setup.

Why is this sold as new surplus?
This unit was pulled from sealed OEM overstock or an unfulfilled project before installation. We perform full electrical validation on our test rigs, but we aren’t replacing the internal coil or re-calibrating the sensitivity. You are getting unused factory components with original manufacturing tolerances at a fraction of the active OEM list price.