Description
The Bently Nevada 330425-02-05 is an industrial-grade, piezoelectric accelerometer designed for critical machinery casing vibration measurements. It is primarily used in high-frequency applications such as gear mesh monitoring, rolling element bearing analysis, and aerodynamic path disturbances. The unit provides an amplitude range of 75 g peak and delivers a scaled electrical output to continuous asset protection architectures like the Bently Nevada 3500/42M or 3500/44M monitor modules.
Commercial Availability & Terms
- Condition: New Original (Factory Sealed Surplus) or Refurbished (Tested and Calibrated)
- Warranty: 12-Month Mechanical & Electrical Performance Warranty
- Availability: In Stock
- Standard Lead Time: 1–3 business days for global express dispatch
- Pricing Note: Prices vary based on stock allocations and certification updates. Contact our engineering sales desk for a formal, time-bound quotation.
Part Number Breakdown (330425-AA-BB)
The specific model alphanumeric suffix configuration dictates the structural footprint and regulatory envelope of the transducer:
- 330425: Base Model Casing Acceleration Transducer (25 mV/g Sensitivity)
- -02 (AA Option): M8 × 1 integral mounting stud
- -05 (BB Option): Multiple International Agency Approvals (Combined CSA/NRTL/C, ATEX, and IECEx certifications for Zone 0, Zone 1, and Zone 2 hazardous areas)
Technical Specifications
| Parameter | Value / Specification |
| Sensitivity | 2.5 mV/m/s^2 (25 mV/g) \pm5\% calibrated at 100 Hz |
| Frequency Response | 10 Hz to 15 kHz (\pm3 dB); Resonant peak occurs above 30 kHz |
| Amplitude Range | 75 g peak overall acceleration within the operational frequency span |
| Excitation Voltage | -24 V DC (\pm0.5 V DC) input through external monitor infrastructure |
| Bias Current | 2 mA nominal operating current draw |
| Output Bias Voltage | -8.5 V DC (\pm0.5 V DC) relative to COM |
| Housing Material | Hermetically sealed 316L stainless steel; IP68 ingress protection rating |
| Electrical Connector | Top-mounted 3-pin MIL-C-5015 receptacle |
| Operating Temperature | -55 to +121 ^\circC (-67 to +250 ^\circF) continuous ambient |
| Mounting Torque | Maximum 4.1 N\cdotm (3.0 ft\cdotlb) using precision torque wrench |
Field Installation & Engineering Constraints
When deploying the 330425-02-05 onto rotating machinery casings, ensure strict adherence to these field mounting criteria:
- Surface Planarity: The mounting location must be machined flat to a surface finish of at least 32 micro-inches rms. An uneven casing surface distorts the sensor base, introducing base strain errors that manifest as false low-frequency vibration trends in the DCS/DAs system.
- Cabling and Boot Constraints: Use a 3-conductor shielded interconnect cable (such as the Bently Nevada 16925 or 16710 series). For wet or oil-mist environments, an elastomer boot must be specified over the MIL-C-5015 connection to maintain the IP68 seal. Ground the cable shield exclusively at the monitor rack; do not ground it at the sensor housing to prevent ground loops.
- High-Frequency Attenuation: High-frequency vibration attenuates rapidly across mechanical interfaces. Avoid mounting the sensor on thin housing covers or structural brackets. Position the sensor directly over the bearing centerline or rigid casing buttresses for optimal signal propagation.
Frequently Asked Questions
What differentiates the 330425 from the standard 330400 accelerometer?
The core difference lies in the sensitivity and amplitude trade-off. The 330400 provides a higher sensitivity (100 mV/g) but is capped at a 50 g peak range to meet API 670 standards. The 330425 drops the sensitivity to 25 mV/g to prevent internal electronics saturation, allowing the sensor to track higher impact energies up to 75 g peak, making it ideal for high-vibration gear teeth mesh.
Can I replace an existing 330425-01-05 sensor with this 330425-02-05 model?
No, they are not directly interchangeable on the same mounting pad. The -01 option uses a 1/4-28 UNF integral stud, whereas this -02 unit features an M8 × 1 metric stud. Attempting to force the metric thread into a unified fine tapped hole will strip the casing threads or damage the sensor base. You must tap a new M8 adapter hole or change the part selection.
How do I troubleshoot a “Sensor Drive Limit” or tracking fault on the monitoring rack?
First, check the DC bias voltage across the terminal block. A healthy 330425 sensor will show a stable bias voltage between -8.0 V DC and -9.0 V DC. If the reading is close to 0 V DC, it indicates a shorted cable or field wire. A reading near the supply voltage (-24 V DC) points to an open circuit, a disconnected MIL connector, or an internal open-circuit failure within the piezoelectric element.
