Bently Nevada 330400-01-05 Three-Wire Piezoelectric Accelerometer

Product Overview

The Bently Nevada 330400-01-05 is a three-wire piezoelectric accelerometer designed for critical machinery applications where casing acceleration measurements are required, such as gear mesh monitoring. It meets the requirements of API Standard 670 for accelerometers and provides an amplitude range of 50 g peak with a sensitivity of 100 mV/g. The -01 suffix specifies a ¼-28 UNF integral stud mounting, and the -05 suffix provides multiple hazardous area approvals (CSA, ATEX, IECEx) for global deployment.

Key Specifications

• Product Type: Piezoelectric Accelerometer / Acceleration Transducer
• Mounting Thread: ¼-28 UNF integral stud
• Agency Approvals: 05 = Multiple (CSA, ATEX, IECEx)
• Sensitivity: 10.2 mV/m/s² (100 mV/g) ±5%
• Acceleration Range: 490 m/s² (50 g) peak overall
• Amplitude Linearity: ±1% to 490 m/s² (50 g) peak
• Frequency Response: 10 Hz to 15 kHz (±3 dB); 30 Hz to 10 kHz (±10%)
• Broadband Noise Floor: 0.039 m/s² (0.004 g) rms (10 Hz to 15 kHz)
• Mounted Resonant Frequency: >30 kHz
• Transverse Sensitivity: <5% of axial
• Temperature Sensitivity: -11% to +3% typical over operating range
• Operating Temperature: -55°C to +121°C (-67°F to +250°F)
• Storage Temperature: -55°C to +121°C (-67°F to +250°F)
• Relative Humidity: 100% condensing (case hermetically sealed)
• IP Rating: Equivalent to IP68 (sensor only)
• Power Requirements: -24 ±0.5 Vdc; 2 mA nominal bias current
• Output Bias Voltage: -8.5 ±0.5 Vdc
• Grounding: Case isolated
• Case Material: 316L stainless steel
• Dimensions: 23 mm (0.93 in) diameter x 59 mm (2.3 in) height (including stud)
• Weight: 100 g (3.5 oz) typical (without cable)
• Mounting Torque: 4.1 N·m (3.0 ft·lb)
• Shock Survivability: 49,050 m/s² (5,000 g) peak maximum

Features & Benefits

• API 670 compliant — meets the stringent requirements of the American Petroleum Institute Standard 670 for accelerometers, ensuring acceptance in oil & gas, petrochemical, and power generation specifications
• Multiple hazardous area approvals — CSA (Class I, Div 1 Groups A-D), ATEX (Ex ia IIC T4 Ga), and IECEx certifications enable installation in North American, European, and international hazardous locations without additional barriers
• Case-isolated design — eliminates ground loop issues and electrical noise pickup from the machine casing, improving signal integrity in electrically noisy environments
• Hermetically sealed 316L stainless steel case — withstands 100% condensing humidity and corrosive atmospheres; equivalent to IP68 rating for the sensor body
• Wide frequency response — 10 Hz to 15 kHz captures gear mesh frequencies, bearing defect frequencies, and blade pass frequencies on most rotating equipment
• Low noise floor — 0.004 g rms broadband noise enables early detection of incipient bearing and gear faults before they reach alarm thresholds

Typical Applications

• Gear mesh monitoring on large gearboxes and speed reducers
• Bearing housing acceleration measurement on turbines, compressors, and pumps
• Reciprocating compressor crosshead acceleration monitoring
• Machine tool spindle vibration monitoring
• Wind turbine gearbox and generator bearing health monitoring
• Hazardous area installations in refineries, offshore platforms, and chemical plants

Installation Guide

1. Verify hazardous area classification — confirm your zone (Class I, Div 1 or ATEX Zone 0/1) and ensure the -05 approval suffix matches your safety documentation and barrier requirements.
2. Prepare mounting surface — machine a flat, smooth surface (32 μin rms or better) on the bearing housing or machine casing. Clean with isopropyl alcohol to remove oil and debris.
3. Tap mounting hole — drill and tap a ¼-28 UNF hole perpendicular to the measured surface. Hole depth must accommodate the integral stud plus one full thread engagement.
4. Apply mounting torque — tighten to 4.1 N·m (3.0 ft·lb) using a torque wrench. Overtightening cracks the piezoelectric crystal; undertightening introduces base strain error and reduces high-frequency response.
5. Connect cable — use Bently Nevada interconnect cable (130539, 16925, or 16710 series) with the 3-pin MIL-C-5015 connector. Ensure the connector is fully threaded and sealed.
6. Apply -24 Vdc power — connect to a regulated -24 Vdc supply. Verify output bias voltage of -8.5 Vdc and sensitivity of 100 mV/g using a calibrated vibration source or shaker table.
7. Route cable away from EMI — maintain 300 mm separation from VFD cables, motor leads, and welding cables. Use shielded cable with the shield grounded at the monitor end only.

FAQ

Q: What is the difference between 330400-01-05 and 330400-01-00?
A: The 330400-01-05 has multiple hazardous area approvals (CSA, ATEX, IECEx), while the 330400-01-00 has no agency approvals. Both have the same ¼-28 UNF mounting thread and 100 mV/g sensitivity. Choose -05 for hazardous area installations; choose -00 for general-purpose, non-hazardous applications.

Q: What is the difference between 330400-01-05 and 330400-02-05?
A: The -01 suffix indicates ¼-28 UNF integral stud mounting; the -02 suffix indicates M8 x 1 integral stud mounting. Both have the same electrical specifications and -05 approvals. Choose based on your machine's threaded hole standard (Imperial vs. Metric).

Q: Can I use this accelerometer for velocity measurement?
A: While the output can be integrated to velocity, Bently Nevada does not recommend this for high-quality velocity measurements. Integration amplifies low-frequency noise and can produce misleading results. For velocity monitoring, use the 330500 Velomitor Sensor instead.

Q: What cable should I use with this accelerometer?
A: Bently Nevada recommends 130539-XX (18 AWG shielded), 16925-XX (22 AWG shielded), or 16710-XX (22 AWG armored) interconnect cables. Order cable length in 1-foot increments from 6 ft to 99 ft. Maximum total cable length is 305 meters (1,000 ft) with no signal degradation.

Q: Is a mounting base required?
A: For sensors with serial numbers preceded by the letter "G" (shipped after April 2004), the mounting base is optional as base strain sensitivity is already low (0.005 g/μstrain). For older sensors (no "G" prefix), Bently Nevada strongly recommends using mounting base 37439-01 to reduce base strain error from 0.100 g/μstrain to 0.0005 g/μstrain.

Selection Tips

• Choose 330400-01-05 when you need ¼-28 UNF mounting and hazardous area approvals for global deployment.
• If your machine has M8 x 1 threaded holes, select 330400-02-05 to avoid adapter bushings and potential loosening issues.
• For non-hazardous areas, save cost with 330400-01-00 (¼-28 UNF, no approvals) or 330400-02-00 (M8 x 1, no approvals).
• If you need 75 g peak range and 25 mV/g sensitivity for high-g applications, consider the 330425 series instead of 330400.
• Always use a torque wrench set to 4.1 N·m (3.0 ft·lb) during installation — overtightening is the leading cause of accelerometer failure in the field.
• Verify your signal conditioner or monitor input meets the 10 kΩ minimum load requirement to prevent signal attenuation.