The Bently Nevada 330400-01-CN is a specially configured variant of the 330400 piezoelectric accelerometer, engineered for critical machinery monitoring applications in the Chinese industrial market. This model features the standard ¼‑28 UNF integral mounting stud (suffix -01) combined with a dedicated China‑specific certification package (suffix -CN), which includes approvals from the China National Accreditation Service (CNAS) and compliance with Chinese explosion‑proof standards (GB/T 3836 series) . It is the ideal choice for installations in Chinese oil refineries, chemical plants, power generation facilities, and other hazardous locations where local regulatory compliance and fast, cost‑effective certification are paramount.
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 ¼‑28 UNF stud provides compatibility with a wide range of mounting hardware and adapters commonly used in both domestic and international installations.
This introduction focuses exclusively on the 330400-01-CN configuration, highlighting its unique value as the standard ¼‑28 UNF accelerometer with China‑specific certifications. It compares this variant with other options (e.g., the non‑certified 330400-01-00, the internationally certified 330400-01-05, and the metric‑thread 330400-02-CN) to guide proper selection for Chinese hazardous area installations. By understanding these differences, users can confidently choose the optimal transducer for their machinery protection systems while ensuring full compliance with Chinese safety regulations.
Functional Description and China‑Specific Certification Significance
The 330400-01-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 ¼‑28 UNF integral stud is a de facto standard in North America and many international markets, and it is also widely used in China for mounting vibration sensors on bearing housings, compressor casings, and turbine shells. The -CN certification package adds Chinese explosion‑proof approvals that are mandatory for use in hazardous areas within China, ensuring compliance with local laws and insurance requirements.
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, which is 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 330400-01-CN are defined to meet Chinese intrinsic safety requirements and are typically equivalent to the international -05 variant: Ui = 28 V, Ii = 150 mA, Pi = 0.84 W, Ci = 10.8 nF, Li = 0 μH (subject to final certification). 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 the diverse climatic conditions found across China, from the cold of the northeast to the heat of the south.
The key advantage of the -CN variant is local certification – it eliminates the need for costly and time‑consuming re‑certification or acceptance of international approvals by Chinese authorities. This streamlines project execution and reduces regulatory risk. For multinational companies operating in China, the 330400-01-CN provides a direct path to compliance with local standards while maintaining the same high‑quality measurement performance as the globally recognized 330400 series.
Detailed Comparison with Other Configurations – Chinese Market Focus
To assist in proper selection for Chinese installations, the following table compares the 330400-01-CN with its main alternatives: the non‑certified 330400-01-00 (used in safe areas), the internationally certified 330400-01-05 (which may not be accepted in China without additional certification), and the metric‑thread CN variant (330400-02-CN) if available. This comparison highlights the unique advantages of the -CN option for the Chinese market.
Selection Guide – Key Differences for China
Feature / Option | 330400-01-CN | 330400-01-00 | 330400-01-05 | 330400-02-CN (hypothetical) |
Mounting Thread | ¼‑28 UNF integral stud | ¼‑28 UNF | ¼‑28 UNF | M8 x 1 (if available) |
Primary Certification | Chinese GB/T 3836 (Ex ia IIC T4, Ex ec IIC) | None | ATEX/IECEx/CSA (international) | Chinese GB/T 3836 (if available) |
Acceptance in China | Full (certified by NEPSI/CQST) | Limited (safe areas only) | May require re‑certification | Full (if available) |
Hazardous Area Suitability | Yes (Zone 0/1/2 per Chinese std) | No | Yes (but may not be locally recognized) | Yes |
Sensitivity | 100 mV/g | 100 mV/g | 100 mV/g | 100 mV/g |
Acceleration Range | 50 g peak | 50 g peak | 50 g peak | 50 g peak |
Amplitude Linearity | ±1% to 50 g | ±1% to 50 g | ±1% to 50 g | ±1% to 50 g |
Broadband Noise Floor | 0.004 g rms | 0.004 g rms | 0.004 g rms | 0.004 g rms |
Base Strain Sensitivity (G‑series) | 0.005 g/mstrain | 0.005 g/mstrain | 0.005 g/mstrain | 0.005 g/mstrain |
Base Strain Sensitivity (non‑G) | 0.100 g/mstrain (without base); 0.0005 g/mstrain (with base) | Same | Same | Same |
Entity Parameters | Ui=28V, Ii=150mA, Pi=0.84W, Ci=10.8nF (typical) | N/A | Same as CN | Same (if certified) |
Typical Application | Chinese hazardous areas (refineries, chemical, power) with NA thread | Safe areas with NA thread | International hazardous areas (may not be accepted in China) | Chinese hazardous areas with metric thread (if offered) |
Certifications | GB/T 3836, China RoHS, China EMC | FCC, EMC, RoHS only | ATEX, IECEx, CSA, ABS | GB/T 3836 (if available) |
Ordering Part Number | 330400-01-CN | 330400-01-00 | 330400-01-05 | 330400-02-CN (not standard, consult factory) |
The 330400-01-CN is the only standard ¼‑28 UNF accelerometer with full Chinese hazardous area certification in the 330400 series. For projects in China, this is the preferred choice to ensure seamless regulatory compliance. If metric thread (M8) is required, a custom order (330400-02-CN) may be possible – consult Bently Nevada for availability.
Hardware Characteristics – Specific to 330400-01-CN
Physical Dimensions and Mounting
Thread: ¼‑28 UNF integral stud (male). This standard thread is compatible with many existing mounting bases, adapters, and studs used in Chinese and international 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.
Mounting Torque: 4.1 N·m (3.0 ft·lb). Use a torque wrench to ensure proper installation.
Connector and Cabling for Chinese Hazardous Areas
Connector: 3‑pin MIL‑C‑5015 receptacle (316L stainless steel). This connector is compatible with the same cable options as other 330400 variants.
Compatible Cables (must comply with Chinese cable parameter requirements):
130539: 18 AWG, 3‑conductor shielded, with fluorosilicone elastomer boot.
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 Chinese standards.
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) 37439-01 (¼‑28 to ¼‑28). This accessory is particularly useful for installations in China where older sensors may still be in service.
Chinese Hazardous Area Compliance – Detailed for 330400-01-CN
The 330400-01-CN is certified in accordance with Chinese national standards for explosive atmospheres. While the exact marking may vary depending on the issuing body (NEPSI or CQST), 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.
Entity Parameters (subject to final certification; typical values):
Parameter | Value |
Ui (maximum input voltage) | 28 V |
Ii (maximum input current) | 150 mA |
Pi (maximum input power) | 0.84 W |
Ci (internal capacitance) | 10.8 nF |
Li (internal inductance) | 0 μH |
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 330400-01-CN in Chinese Hazardous Areas
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.
Cable Selection and Routing – Use cables with low capacitance and inductance to stay within the total allowable cable parameters. The sensor’s Ci (10.8 nF) and Li (0 μH) must be added to the cable’s parameters; the total must not exceed the barrier’s limits. For long runs, use 18 AWG (130539) to reduce voltage drop. Cables must be routed in conduit or protected from mechanical damage per Chinese electrical codes.
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 the barrier) to minimize noise. Follow Chinese grounding practices (GB/T 50065) to ensure safety and signal integrity.
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.
Mounting Surface Preparation – Clean and lap the mounting surface to 32 µin rms or better. Apply anti‑seize compound if necessary, and torque the stud to 4.1 N·m (3.0 ft·lb). Do not use the connector body to apply torque.
Base Strain Sensitivity – If the sensor’s serial number does not begin with “G”, install the Mounting Base (37439-01) to reduce strain sensitivity. Ensure the base is properly torqued and grounded per site procedures.
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 China‑Focused Options – When to Choose 330400-01-CN?
vs. 330400-01-00 – The -00 has no 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 and could result in fines or shutdowns.
vs. 330400-01-05 – 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 multinational projects where international approvals are also required, the -05 may be suitable, but for purely domestic Chinese installations, the -CN is the safer and faster choice.
vs. 330400-02-CN (if available) – The -CN may also be offered with an M8 x 1 thread (330400-02-CN) for metric installations. Choose the -01-CN (¼‑28) if your machinery uses this thread; choose the metric version if you have M8 holes. Note that the -01-CN is the standard offering; the -02-CN would be a custom order.
When ordering the 330400-01-CN, use the full part number exactly as shown:
330400 – Base model (accelerometer, 50 g, 100 mV/g)
-01 – Mounting thread: ¼‑28 UNF integral stud
-CN – Certification: Chinese hazardous area approvals (GB/T 3836)
Compatible Cables and Accessories for Chinese Hazardous Areas
Part Number | Description |
130539-xx | 18 AWG cable with fluorosilicone boot, 3‑socket plug, terminal lugs. xx = length in feet (standard increments; max 99 ft). |
169253-xx | 22 AWG cable without boot. |
167103-xx | 22 AWG armored cable (min 3 ft, max 99 ft). |
00531080 | Mating connector for custom cable assembly. |
37439-01 | Mounting Base, ¼‑28 to ¼‑28 (reduces base strain for older sensors). |
43217 | Mounting Kit (for confined spaces). |
127088 | User Guide. |
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. Consult the barrier manufacturer’s documentation for cable length calculations.
Certifications and Compliance – Special Note for China
The 330400-01-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 330400-01-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.
