Bently Nevada 330400-02-CN Accelerometer Acceleration Transducer

The Bently Nevada 330400-02-CN is a specialized configuration of the 330400 piezoelectric accelerometer, engineered for critical machinery monitoring in metric-standard hazardous locations within the Chinese industrial market. This variant features an M8 x 1 integral mounting stud (suffix -02) combined with a dedicated China-specific certification package (suffix -CN), which includes approvals from recognized Chinese testing bodies such as NEPSI or CQST in accordance with GB/T 3836 series standards. It is the definitive choice for installations in Chinese oil refineries, chemical plants, power generation facilities, and offshore platforms that require both metric thread compatibility and compliance with local explosion-proof regulations.

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 -CN variant retains 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 specific certifications required for use in Zone 0, Zone 1, and Zone 2 hazardous areas under Chinese regulations. Its case-isolated design eliminates ground loops, and the integral M8 stud provides robust, low-loss mechanical coupling with metric hardware, eliminating the need for thread adapters that can compromise high-frequency response.

This introduction focuses exclusively on the 330400-02-CN configuration, highlighting its unique value as the only standard metric-threaded accelerometer with full Chinese hazardous area certification in the 330400 family. It compares this variant with other options (e.g., the non-certified 330400-02-00, the ¼-28 Chinese-certified 330400-01-CN, and the internationally certified 330400-02-05) to guide proper selection for metric hazardous installations in China. By understanding these differences, users can confidently choose the optimal transducer for their machinery protection systems while ensuring seamless regulatory compliance.

Functional Description and Metric Thread Advantage with Chinese Certification

The 330400-02-CN accelerometer operates on the piezoelectric principle, converting mechanical acceleration into an electrical charge that is conditioned into a low-impedance voltage signal with a sensitivity of 100 mV/g (10.2 mV/m/s²). The M8 x 1 integral mounting stud is the preferred metric thread for vibration sensors in many parts of the world, particularly in Europe, Asia, and China, where International Organization for Standardization (ISO) metric fasteners are the standard. The M8 thread offers a slightly larger diameter (8 mm vs. ¼-28 UNF's ~6.35 mm) and finer pitch (1 mm vs. 28 TPI), providing greater thread engagement and resistance to loosening under vibration—a critical advantage in high-vibration environments.

The -CN certification package adds Chinese explosion-proof approvals that are mandatory for use in hazardous areas within China, ensuring compliance with local laws, insurance requirements, and safety regulations. The sensor carries certifications in accordance with Chinese national standards GB/T 3836.1 (General Requirements), GB/T 3836.4 (Intrinsic Safety), and GB/T 3836.15 (Installation Requirements) . It is approved for Ex ia IIC T4 Ga (intrinsic safety, Zone 0/1) and Ex ec IIC Gc (increased safety, Zone 2) under the Chinese certification system, typically issued by recognized testing bodies such as NEPSI (National Supervision and Inspection Center for Explosion Protection and Safety of Instrumentation) or CQST (China Quality Supervision and Testing Center for Explosion Protected Electrical Products) . The -CN variant also complies with China RoHS and China EMC requirements, making it a fully compliant solution for the local market.

The entity parameters for the 330400-02-CN are defined to meet Chinese intrinsic safety requirements and are equivalent to other -05/-CN variants: Ui = 28 V, Ii = 150 mA, Pi = 0.84 W, Ci = 10.8 nF, Li = 0 μH. These parameters ensure compatibility with Chinese-approved intrinsic safety barriers and isolators. The sensor's wide operating temperature range (-55°C to +121°C) and IP68 rating ensure reliable performance in China's diverse climatic conditions, from the cold of Heilongjiang to the heat of Hainan.

The combination of the M8 thread and Chinese hazardous area approvals makes the 330400-02-CN a globally versatile yet locally compliant transducer. It eliminates the need for thread adapters (which can introduce mechanical resonances and reduce high-frequency accuracy) while meeting China's strictest safety standards. For multinational companies operating in China with metric-standard machinery, this configuration provides a direct path to compliance without compromising measurement integrity.

Detailed Comparison with Other Configurations – Chinese Market Focus

To assist in proper selection for Chinese installations with metric requirements, the following table compares the 330400-02-CN with its main alternatives: the non-certified metric version (330400-02-00), the ¼-28 Chinese-certified version (330400-01-CN), and the internationally certified metric version (330400-02-05). This comparison highlights the unique value of the -02-CN for metric hazardous Chinese applications.

Selection Guide – Key Differences for China with Metric Threads

The 330400-02-CN is the only standard metric-threaded accelerometer with full Chinese hazardous area certification in the 330400 series. For Chinese installations with M8 mounting, this is the clear choice. If your machinery uses ¼-28 UNF threads, choose 330400-01-CN instead. For international hazardous areas where Chinese certification is not required, the 330400-02-05 may be suitable, but it may not be accepted in China without additional certification.

Hardware Characteristics – Specific to 330400-02-CN

Physical Dimensions and Mounting

• Thread: M8 x 1 integral stud (male). This metric thread is widely used in Chinese and international machinery, providing excellent holding power and compatibility with standard M8 mounting holes.

• 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). Use a torque wrench to avoid over-tightening.

Connector and Cabling for Chinese Hazardous Areas

• Connector: 3-pin MIL-C-5015 receptacle (316L stainless steel). This connector is compatible with all 330400 series cables.

• Compatible Cables (must comply with Chinese cable parameter requirements):

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

  • 169253: 22 AWG, 3-conductor shielded.

  • 167103: 22 AWG, armored cable.

• Maximum Cable Length: 305 metres (1000 ft) – but must be derated based on cable capacitance and inductance to stay within the barrier's limits, as per GB/T 3836.15.

• 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). This accessory is particularly useful for installations in China where older sensors may still be in service, and it is recommended to ensure optimal low-frequency performance.

Chinese Hazardous Area Compliance – Detailed for 330400-02-CN

The 330400-02-CN is certified in accordance with Chinese national standards for explosive atmospheres. Typical approval includes:

• Ex ia IIC T4 Ga – Intrinsically safe for Zone 0 (continuous presence of explosive gas) and Zone 1, suitable for Gas Group IIC (hydrogen, acetylene) and T4 temperature class (≤135°C surface temperature).

• Ex ec IIC Gc – Increased safety for Zone 2.

• IP68 – Dust-tight and watertight, per GB/T 4208.

• The sensor is also compliant with China RoHS (SJ/T 11364) with an EFUP (Environmental Friendly Use Period) of 15 years.

Entity Parameters (subject to final certification; typical values):

Conditions of Safe Use (per GB/T 3836):

• The sensor must be connected to an associated intrinsically safe apparatus that meets the entity parameters and is certified to Chinese standards.

• Cable parameters (capacitance, inductance) must be within the limits specified by the barrier manufacturer and the Chinese certification.

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

• The mating connector must provide at least IP54 ingress protection as required by GB/T 3836.15.

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

Installation Best Practices for 330400-02-CN in Metric Chinese Hazardous Areas

1. Intrinsic Safety Barrier – Always connect the sensor through a Chinese-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 that comply with GB/T 3836.4.

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. 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 per Chinese standards.

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. Follow Chinese grounding practices (GB/T 50065).

4. Connector Sealing – In hazardous areas, ensure the 3-pin MIL connector is properly mated and sealed (IP54 or better) as required by GB/T 3836.15. Use appropriate cable glands and sealing compounds that are certified for use in China.

5. Mounting Surface Preparation – Clean and lap the mounting surface to 32 µin rms or better. The M8 hole must be perpendicular to the measurement axis. 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.

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.

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 in China's diverse climate.

Comparison with Other Options – When to Choose 330400-02-CN?

• vs. 330400-02-00 – The -00 lacks any hazardous area approvals. For any Chinese installation in a classified area (Zone 0, 1, or 2), the -CN is mandatory. Using the -00 in a hazardous area would violate Chinese safety regulations.

• vs. 330400-01-CN – Both have identical Chinese certifications. The -01 uses ¼-28 UNF thread, while the -02 uses M8. Choose 330400-02-CN if your machinery has metric mounting holes (common in European-designed plants, many new Chinese facilities, and international joint ventures). Using the correct thread eliminates the need for adapters, which can degrade high-frequency response.

• vs. 330400-02-05 – The -05 carries ATEX/IECEx/CSA certifications, which may not be directly accepted by Chinese authorities without additional testing and approval. The -CN variant has been pre-approved to Chinese standards (GB/T 3836), saving time and cost on project certification. For purely domestic Chinese installations, the -CN is the safer and faster choice.

Ordering Information

When ordering the 330400-02-CN, 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

• -CN – Certification: Chinese hazardous area approvals (GB/T 3836)

Compatible Cables and Accessories for Chinese Hazardous Areas

Important: When ordering cables for hazardous areas in China, ensure they are suitable for use with the certified barrier and comply with the cable parameter requirements of GB/T 3836.15.

Certifications and Compliance – Special Note for China

The 330400-02-CN is certified to GB/T 3836.1 (General Requirements), GB/T 3836.4 (Intrinsic Safety), and GB/T 3836.15 (Installation Requirements) . It is also compliant with China RoHS (SJ/T 11364) and China EMC (GB/T 18268.1). For the most current approval certificates (including the specific issuing body and marking), refer to the Bently Nevada China office or the Approvals Quick Reference Guide (108M1756). Always verify that the certification is valid for your specific hazardous area classification and temperature class.

Warranty and Support

The Bently Nevada 330400-02-CN is covered under the standard manufacturer's warranty. For technical support, application assistance, or help with Chinese certification documentation, contact your local Bently Nevada representative in China or access the Bently Nevada Media Library at bntechsupport.com. Bently Nevada has a strong local presence in China to support customers with site surveys, installation guidance, and regulatory compliance.