Bently Nevada 330400-02-00 Accelerometer Acceleration Transducer

The Bently Nevada 330400-02-00 is a high-performance piezoelectric accelerometer specifically configured for critical machinery monitoring applications where metric mounting standards are required and hazardous area certifications are not necessary. This variant (suffix -02-00) features an M8 x 1 integral mounting stud and carries no agency approvals for explosive atmospheres, making it the ideal choice for industrial installations in non‑classified areas that adhere to International Organization for Standardization (ISO) metric fastening conventions. It is particularly well‑suited for European, Asian, and other global markets where M8 threads are the norm for mounting vibration sensors on bearing housings, compressor casings, and turbine shells.

The 330400 series is engineered to meet the rigorous demands of American Petroleum Institute (API) Standard 670 for accelerometers, ensuring reliable casing acceleration measurements for gear mesh monitoring, bearing fault detection, and general machine condition monitoring. The -02-00 variant delivers the same core performance as its ¼‑28 UNF counterpart: 50 g peak amplitude range, 100 mV/g sensitivity, broad frequency response from 10 Hz to 15 kHz, and IP68‑rated hermetic sealing for harsh environments. Its case‑isolated design eliminates ground loops, and the integral M8 stud provides a secure, low‑loss mechanical coupling with metric hardware.

This introduction focuses exclusively on the 330400-02-00 configuration, highlighting its unique metric‑thread feature, comparing it with other options (e.g., the 330400-01-00 with ¼‑28 UNF, and the certified -05 versions), and providing detailed guidance for selection based on thread preference and environmental requirements. By understanding these differences, users can confidently choose the optimal transducer for their machinery protection systems.

Functional Description and Metric Thread Advantage

The 330400-02-00 accelerometer operates on the piezoelectric principle, converting mechanical acceleration into an electrical charge that is conditioned into a low‑impedance voltage signal. Its sensitivity of 100 mV/g (10.2 mV/m/s²) provides a strong, noise‑resistant output for general‑purpose vibration monitoring. The key differentiator of the -02-00 is its M8 x 1 integral mounting stud, which is the preferred thread size in many parts of the world, particularly in Europe, Asia, and regions following ISO standards. This metric thread is compatible with a wide range of mounting bases, adapters, and existing installations that use M8 fasteners, eliminating the need for thread adapters that can introduce additional mechanical compliance and reduce high‑frequency response.

The M8 stud offers a slightly larger diameter (8 mm vs. ¼‑28 UNF’s ~6.35 mm) and a finer pitch (1 mm vs. 28 TPI), providing greater thread engagement and resistance to loosening under vibration. This can be particularly advantageous in high‑vibration environments where secure mounting is critical for measurement integrity. The -02-00 is thus a natural choice for machinery OEMs and end‑users who have standardized on metric hardware.

The transducer is optimized for casing‑mounted measurements on bearing housings, compressor cases, turbine shells, and gearboxes. It excels at detecting high‑frequency phenomena such as gear mesh frequencies, blade pass vibrations, and bearing defect signatures—where its ±3 dB response up to 15 kHz and ±10% response up to 10 kHz provide reliable data. The low noise floor (0.004 g rms) ensures that small amplitude signals are not masked, enabling early fault detection.

Unlike the 330425 variant, which offers 75 g range and 25 mV/g sensitivity for higher‑amplitude applications, the 330400-02-00 is tailored for moderate vibration levels (up to 50 g peak) with superior signal‑to‑noise ratio. The -00 suffix indicates no hazardous area approvals, making it lighter and slightly less expensive than the -05 version (which carries multiple certifications). This trade‑off is acceptable for installations in safe (non‑classified) areas.

Detailed Comparison with Other Configurations

To assist in proper selection, the following table compares the 330400-02-00 with its main alternatives: the standard 330400-01-00 (¼‑28 UNF, no approvals), the 330400-01-05 (¼‑28 UNF with hazardous area approvals), and the 330425 series for higher amplitude requirements. This comparison highlights the unique value of the -02-00 for metric‑thread applications.

Selection Guide – Key Differences

The 330400-02-00 is the only standard metric‑thread version without approvals in the 330400 family. If you require metric thread and hazardous area approvals, you would need to order a custom variant (not listed, likely -02-05) or use an adapter (not recommended for critical high‑frequency measurements). For applications with vibration exceeding 50 g, the 330425 series with M8 thread can be custom‑ordered, but the standard offering is the -01-00 for ¼‑28. Therefore, the 330400-02-00 fills a specific niche for metric‑favoring safe‑area installations.

Hardware Characteristics – Specific to 330400-02-00

Physical Dimensions and Mounting

• Thread: M8 x 1 integral stud (male). This metric thread is widely used in ISO‑compliant machinery and provides excellent holding power.

• Height: 59 mm (2.3 in) including stud.

• Diameter: 23 mm (0.93 in).

• Weight: 99 g (3.5 oz) typical (no cable).

• Mounting Surface Finish: Recommended 32 µin rms or better (equivalent to ~0.8 µm Ra).

• Mounting Torque: 4.1 N·m (3.0 ft·lb) – same as for ¼‑28 UNF. Do not over‑tighten; use a torque wrench.

Connector and Cabling

• Connector: 3‑pin MIL‑C‑5015 receptacle (316L stainless steel). This is the standard connector for all 330400 series accelerometers.

• Compatible Cables:

  • 130539: 18 AWG, 3‑conductor shielded, with fluorosilicone elastomer boot at one end, terminal lugs at the other.

  • 169253: 22 AWG, 3‑conductor shielded, without boot.

  • 167103: 22 AWG, armored cable.

• Maximum Cable Length: 305 metres (1000 ft) without signal degradation.

• Mating Connector: 00531080 for custom cable assemblies.

Environmental and Electrical Specifications

The 330400-02-00 shares identical electrical and environmental performance with all 330400 variants:

• Power: -24 V dc ±0.5 V, 2 mA nominal bias current.

• Output Bias Voltage: -8.5 V dc ±0.5 V.

• Grounding: Case isolated (the housing is electrically isolated from the mounting stud to prevent ground loops).

• Operating/Storage Temperature: -55°C to +121°C (-67°F to +250°F).

• Shock Survivability: 5000 g peak.

• Humidity: 100% condensing (hermetically sealed case).

• IP Rating: IP68 (sensor only) – dust tight and watertight.

• Magnetic Field Susceptibility: < 225 mg/gauss at 50 gauss, 50‑60 Hz.

Base Strain Sensitivity Notes

Base strain sensitivity can affect low‑frequency measurements if the mounting surface flexes. For the 330400-02-00:

• If the serial number begins with “G” (newer production): Base strain sensitivity is only 0.005 g/mstrain – no extra mounting base required.

• If the serial number does NOT begin with “G” (older units, pre‑April 2004): Base strain sensitivity is 0.100 g/mstrain without the mounting base, but reduces to 0.0005 g/mstrain when using the supplied Mounting Base (API adapter). For metric thread, the appropriate mounting base is part number 37439-02 (M8 to M8). Bently Nevada recommends using this base for older units to ensure optimal low‑frequency performance.

Installation Best Practices for 330400-02-00

To achieve accurate, repeatable measurements with the 330400-02-00:

1. Surface Preparation – Clean the mounting surface to remove paint, rust, or debris. Achieve a surface finish of 32 µin rms or better (e.g., by lapping). This ensures proper mechanical coupling and frequency response. For metric surfaces, ensure the tapped hole is M8 x 1 and is perpendicular to the measurement axis.

2. Stud Installation – Apply a thin layer of anti‑seize compound (if required) and hand‑tighten the integral M8 stud into the prepared hole. Then torque to 4.1 N·m (3.0 ft·lb). Do not use the connector housing to apply torque; use a wrench on the hex flats of the stud. The M8 stud is slightly larger than ¼‑28, so ensure you have the correct torque wrench and socket.

3. Cable Connection – Align the 3‑pin connector and tighten the coupling nut securely. For long cable runs, use the recommended 18 AWG cable (130539) to minimise voltage drop and signal loss. Route cables away from high‑voltage lines and avoid sharp bends.

4. Grounding – Because the case is isolated, the sensor does not require a separate ground. However, the cable shield should be connected to the monitoring system’s common reference at the power supply end to minimize electrical noise.

5. Base Strain Consideration – If the sensor’s serial number does not begin with “G”, install the supplied Mounting Base (37439-02 for M8 to M8) between the stud and the machine surface. This reduces base strain sensitivity dramatically.

6. Environmental Protection – For outdoor installations, use splash boots (available separately) and ensure all cable connections are sealed. The sensor itself is IP68, but the cable termination may require additional protection.

Comparison with Metric‑Thread Alternatives – When to Choose 330400-02-00?

• vs. 330400-01-00 – Both are non‑certified and identical in performance. The -02-00 has the M8 thread, which is preferred in metric‑standard countries. If your machinery uses M8 mounting holes, choose -02-00; if it uses ¼‑28, choose -01-00. They are not mechanically interchangeable without adapters, which are discouraged for high‑frequency measurements.

• vs. 330400-01-05 – The -05 adds hazardous area approvals but uses the ¼‑28 thread. If you need both metric thread and approvals, you would need a custom order (e.g., 330400-02-05) – consult Bently Nevada. For non‑hazardous metric applications, the -02-00 is the correct standard option.

• vs. 330425 series – The 330425 offers 75 g range and 25 mV/g sensitivity. Choose 330400-02-00 for higher sensitivity (100 mV/g) when vibration levels are ≤50 g. For higher amplitudes, consider a custom‑order 330425 with M8 thread.

Certifications and Compliance for 330400-02-00

Because the -00 option has no hazardous area approvals, it is certified for general industrial use only. It complies with:

• FCC Part 15 – Radio frequency interference limits.

• EMC Directive 2014/30/EU – Electromagnetic compatibility.

• RoHS Directive 2011/65/EU – Restriction of hazardous substances.

• China RoHS – EFUP of 15 years (SJ/T 11364-2024).

• ABS – (Marine Vessels, Offshore Units) – the sensor itself is approved for maritime use even without explosion protection.

It is NOT rated for ATEX, IECEx, or CSA hazardous locations. If your installation requires intrinsic safety, you must order a variant with the -05 option (e.g., 330400-02-05, custom).

Ordering Information

When ordering the 330400-02-00, use the full part number exactly as shown:

• 330400 – Base model (accelerometer, 50 g, 100 mV/g)

• -02 – Mounting thread: M8 x 1 integral stud

• -00 – Agency approval: None

Compatible Cables and Accessories

Note: The 330400-02-00 does not include a cable; order separately. Ensure cable length does not exceed 305 m.

Warranty and Support

The Bently Nevada 330400-02-00 is covered under the standard manufacturer’s warranty (refer to Bently Nevada Terms and Conditions). For technical support, application assistance, or custom configurations (e.g., metric thread with approvals), contact your local Bently Nevada sales representative or access the Bently Nevada Media Library at bntechsupport.com.