Bently Nevada 330400-02-05 Accelerometer Acceleration Transducer

The Bently Nevada 330400-02-05 is a specialized configuration of the 330400 piezoelectric accelerometer that combines metric mounting with comprehensive hazardous area certifications. This variant features an M8 x 1 integral mounting stud (suffix -02) and carries multiple international agency approvals (suffix -05), including ATEX, IECEx, and CSA. It is specifically engineered for critical machinery monitoring in explosive atmospheres where metric fasteners are the standard, such as in European, Asian, and global facilities that follow ISO mounting conventions. This unique combination makes it the preferred choice for installations in oil refineries, chemical plants, offshore platforms, and other classified locations that require both intrinsic safety and metric hardware compatibility.

The 330400 series is designed to meet American Petroleum Institute (API) Standard 670 for accelerometers, ensuring accurate casing acceleration measurements for gear mesh monitoring, bearing health assessment, and general machine vibration analysis. The -02-05 variant delivers the full performance of the 330400 platform – 50 g peak amplitude range, 100 mV/g sensitivity, 10 Hz to 15 kHz frequency response, and IP68‑rated hermetic sealing – while adding the safety and compliance features necessary for Zone 0, Zone 1, Zone 2, and Division 1/2 hazardous locations. Its case‑isolated design eliminates ground loops, and the integral M8 stud provides a robust, low‑loss mechanical coupling with metric threads, eliminating the need for thread adapters that can compromise high‑frequency response.

This introduction focuses exclusively on the 330400-02-05 configuration, highlighting its unique value as the only standard metric‑threaded, fully certified accelerometer in the 330400 family. It compares this variant with other options (e.g., the non‑certified 330400-02-00, the ¼‑28 certified 330400-01-05, and the higher‑range 330425 series) to guide proper selection for safety‑critical metric installations. By understanding these differences, users can confidently choose the optimal transducer for their machinery protection systems in hazardous areas.

Functional Description and International Certification Significance

The 330400-02-05 accelerometer operates on the piezoelectric principle, generating a charge proportional to acceleration that is converted to a low‑impedance voltage signal with a sensitivity of 100 mV/g (10.2 mV/m/s²). Its M8 x 1 integral stud is the preferred metric thread for mounting vibration sensors on bearing housings, compressor casings, and turbine shells in many parts of the world. The -05 certification package adds intrinsic safety (Ex ia) and increased safety (Ex ec) ratings, allowing installation in the most demanding explosive environments.

The sensor carries the ATEX marking Ex ia IIC T3 Ga for Zone 0/1, Ex ec IIC Gc for Zone 2, and Ex tc IIC Dc for Zone 22 (dust). It is also certified under IECEx with equivalent ratings and by CSA for Class I, Division 1, Groups A, B, C, D; Class II, Groups E, F, G; Class III; and Class I, Division 2 as well as Zone 2 and Zone 22 for North American installations. These approvals are critical for compliance with local regulations and insurance requirements in hazardous areas.

The entity parameters for the 330400-02-05 are identical to those of the -05 variants: Ui = 28 V, Ii = 150 mA, Pi = 0.84 W, Ci = 10.8 nF, Li = 0 μH. These values define the maximum electrical parameters that can be applied to the sensor without compromising intrinsic safety. When connected through an approved intrinsic safety barrier, the sensor can be safely used in Zone 0 environments (continuous presence of explosive gas). The sensor’s wide operating temperature range (-55°C to +121°C) and IP68 rating ensure reliable performance in extreme conditions, from Arctic cold to desert heat.

The combination of the M8 thread and hazardous area approvals makes the 330400-02-05 a globally versatile transducer. It eliminates the need for thread adapters (which can introduce mechanical resonances and reduce high‑frequency accuracy) while meeting the strictest safety standards. For installations that require both metric mounting and certification, this is the standard factory‑offered solution (unlike the ¼‑28 certified version, which is more common in North America).

Detailed Comparison with Other Configurations

To assist in proper selection, the following table compares the 330400-02-05 with its main alternatives: the non‑certified metric version (330400-02-00), the certified ¼‑28 version (330400-01-05), and the higher‑range 330425 series with similar approvals. This comparison highlights the unique positioning of the -02-05.

Selection Guide – Key Differences

The 330400-02-05 is the only standard metric‑threaded, fully certified option in the 330400 series. It provides the perfect solution for international projects where both metric mounting and hazardous area compliance are mandatory. For applications requiring higher amplitude capability (75 g) with metric thread and certifications, the 330425 series would need to be custom‑ordered (not listed as standard), making the 330400-02-05 the more readily available choice for most moderate‑vibration (<50 g) hazardous‑area metric installations.

Hardware Characteristics – Specific to 330400-02-05

Physical Dimensions and Mounting

• Thread: M8 x 1 integral stud (male). This thread is compatible with ISO 261 metric coarse pitch standards, commonly used in European and Asian machinery.

• 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 (~0.8 µm Ra).

• Mounting Torque: 4.1 N·m (3.0 ft·lb) – same as for ¼‑28 UNF. Use a torque wrench to avoid over‑tightening.

Connector and Cabling for Hazardous Areas

• Connector: 3‑pin MIL‑C‑5015 receptacle (316L stainless steel). This connector is approved for use in hazardous areas when properly mated.

• Compatible Cables (must respect intrinsic safety cable parameters):

  • 130539: 18 AWG, 3‑conductor shielded, with fluorosilicone elastomer boot (recommended for rugged environments).

  • 169253: 22 AWG, 3‑conductor shielded (lighter duty).

  • 167103: 22 AWG, armored cable (for mechanical protection).

• Maximum Cable Length: 305 metres (1000 ft) – but must be derated based on cable capacitance and inductance to stay within the barrier’s limits. The total Ci (sensor + cable) and Li (sensor + cable) must not exceed the barrier’s allowable values.

• Mating Connector: 00531080 for custom cable assemblies.

Environmental and Electrical Specifications

• 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 – essential for avoiding ground loops in hazardous installations.

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

• Shock Survivability: 5000 g peak.

• Humidity: 100% condensing (hermetically sealed).

• IP Rating: IP68 (sensor only).

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

Base Strain Sensitivity

• For serial numbers beginning with “G” (newer production): 0.005 g/mstrain – no mounting base required.

• For serial numbers NOT beginning with “G” (older units): 0.100 g/mstrain without base, but reduces to 0.0005 g/mstrain when using the Mounting Base (API adapter) 37439-02 (M8 to M8). Bently Nevada recommends using the base for older units even in hazardous areas; the base itself is non‑incendive and can be installed in classified locations if properly grounded.

Intrinsic Safety and Hazardous Area Approvals – Detailed for 330400-02-05

The 330400-02-05 carries the following markings and certifications (as per the datasheet):

• ATEX:

  • Ex ia IIC T3 Ga (Zone 0/1)

  • Ex ec IIC Gc (Zone 2)

  • Ex tc IIC Dc (Zone 22)

• IECEx: Ex ia IIC T3 Ga, Ex ec IIC Gc, Ex tc IIC Dc

• CSA:

  • Class I, Division 1, Groups A, B, C, D

  • Class II, Groups E, F, G

  • Class III

  • Class I, Division 2, Groups A, B, C, D

  • Class I Zone 2, AEx ec IIC Gc

  • Zone 22, AEx tc IIC Dc

• ABS: Approved for Marine Vessels, Offshore Units, and Mobile Offshore Units.

Entity Parameters (identical for all -05 variants):

Conditions of Safe Use (ATEX/IECEx Zone 0/1):

• The sensor must be connected to an associated intrinsically safe apparatus that meets the entity parameters.

• Cable type A or B (per EN 60079‑25) must be used, respecting cable capacitance and inductance limits.

• Operating ambient temperature: -55°C ≤ Tamb ≤ +121°C.

Conditions for Zone 2 (North America):

• The supply electrical parameters must not exceed the entity parameters.

• The mating connector must provide at least IP54 ingress protection (IEC 60079‑0 and IEC 60079‑7/15).

• Transient protection shall be provided, set at a level not exceeding 140% of the peak rated voltage at the supply terminals.

Requirements for North America (CSA):

• The sensor may only be powered by a power supply unit with a limited energy electric circuit per CAN/CSA C22.2 No. 61010‑1‑12 and ANSI/UL 61010‑1, or Class 2 as defined in the Canadian Electrical Code (C22.1, Section 16‑200) and/or National Electrical Code (NFPA 70), Article 725.121.

Installation Best Practices for 330400-02-05 in Metric Hazardous Areas

1. Intrinsic Safety Barrier – Always connect the sensor through a certified intrinsic safety barrier that limits voltage, current, and power to within the entity parameters. Ensure the barrier’s output parameters (Uo, Io, Po) do not exceed Ui, Ii, and Pi. Use barriers with appropriate cable capacitance and inductance limits.

2. Cable Selection and Length Calculation – The sensor’s Ci (10.8 nF) and Li (0 μH) must be added to the cable’s capacitance and inductance. The total must not exceed the barrier’s allowable cable parameters (usually specified in the barrier’s datasheet). For long runs (>100 m), use lower‑capacitance cables (e.g., 130539 with 18 AWG) to maximize allowable length. The maximum physical length of 305 m (1000 ft) is a guideline; the limiting factor is the electrical parameters.

3. Grounding – The case is isolated, so grounding is not required for the sensor body. However, the cable shield should be grounded at the power supply end (typically at the barrier) to minimize noise. Do not ground the shield at both ends to avoid ground loops.

4. Connector Sealing – In hazardous areas, ensure the 3‑pin MIL connector is properly mated and sealed (IP54 or better) as required by ATEX/IECEx. Use appropriate cable glands and sealing compounds if needed. The connector body is 316L stainless steel for corrosion resistance.

5. Mounting Surface Preparation – Clean and lap the mounting surface to 32 µin rms or better. Apply anti‑seize compound if necessary, and torque the M8 stud to 4.1 N·m (3.0 ft·lb). Do not use the connector body to apply torque. The M8 stud provides a larger thread engagement area than ¼‑28, enhancing stability.

6. Base Strain Sensitivity – If the sensor’s serial number does not begin with “G”, install the Mounting Base (37439-02) to reduce strain sensitivity. Ensure the base is properly torqued and grounded per site procedures. The base is compatible with the M8 thread.

7. Environmental Protection – Although the sensor is IP68, the cable termination and connectors require additional protection (splash boots, conduit, etc.) for outdoor or wet locations. The sensor itself is suitable for outdoor use when installed in a protected enclosure with wiring in conduit.

Comparison with Other Certified Options – Why Choose 330400-02-05?

• vs. 330400-02-00 – The -00 lacks any hazardous area approvals. If your plant has classified areas, the -05 is mandatory. The -05 also adds ABS approval, which is beneficial for marine applications.

• vs. 330400-01-05 – Both have identical approvals. The -01 uses ¼‑28 UNF thread, while the -02 uses M8. Choose 330400-02-05 if your machinery has metric mounting holes (common in Europe, Asia, and many international projects). Using the correct thread eliminates the need for adapters, which can degrade high‑frequency response.

• vs. 330425-01-05 – The 330425 offers 75 g range and 25 mV/g sensitivity with the same approvals but typically with ¼‑28 thread. For metric hazardous applications requiring higher amplitude capability, you would need a custom order (e.g., 330425-02-05). The 330400-02-05 is the standard metric certified option for 50 g range and high sensitivity.

Ordering Information

When ordering the 330400-02-05, 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

• -05 – Agency approval: Multiple (CSA, ATEX, IECEx)

Compatible Cables and Accessories for Hazardous Areas

Important: When ordering cables for hazardous areas, ensure the cable parameters (capacitance, inductance) do not exceed the allowable limits when combined with the sensor’s Ci and Li and the barrier’s specifications. Consult the barrier manufacturer’s documentation for cable length calculations.

Certifications and Compliance – Special Note

The 330400-02-05 is certified for intrinsic safety (Ex ia) and increased safety (Ex ec) and dust protection (Ex tc). It is suitable for use in Gas Groups IIC (hydrogen, acetylene) and IIB (ethylene) and IIA (propane). The temperature class T3 indicates a maximum surface temperature of 200°C under fault conditions, well above the sensor’s operating range.

The sensor is also RoHS compliant and meets China RoHS requirements with an EFUP of 15 years. For the most current approval certificates, refer to the Approvals Quick Reference Guide (108M1756) or visit bntechsupport.com.

Warranty and Support

Bently Nevada (Baker Hughes) provides a standard product warranty covering defects in materials and workmanship. For technical support, application engineering, or assistance with intrinsic safety calculations, contact your local Bently Nevada representative or access the Bently Nevada Media Library at bntechsupport.com.