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The Bently Nevada 330104-03-18-50-02-RU is a high-performance proximity probe system designed for non-contact displacement and vibration measurement in rotating machinery. This model belongs to the 3300 XL 8mm Proximity Probe family, widely recognized for its exceptional linearity, thermal stability, and durability in harsh industrial environments. The probe operates on the eddy current principle, converting physical displacement into an electrical signal proportional to the gap between the probe tip and the target surface.
The 330104-03-18-50-02-RU is a reverse mount configuration, meaning the probe cable exits from the rear of the probe housing, allowing for easier installation in confined spaces where standard side-exit probes cannot fit. It is typically used with a matching proximitor and extension cable to form a complete monitoring channel.
| Parameter | Specification |
|---|---|
| Model Number | 330104-03-18-50-02-RU |
| Probe Diameter | 8 mm |
| Probe Type | Reverse Mount (RU suffix) |
| Total Length | 1.0 meter (1000 mm) from probe tip to connector |
| Thread Size | 3/8-24 UNF-2A |
| Unthreaded Length | 18 mm (from probe tip to start of threads) |
| Overall Case Length | 50 mm |
| Connector Type | 2-pin military style (MS3112 series) |
| Cable Length | 1.0 meter (integral coaxial cable) |
| Cable Type | Armored, fluid-resistant coaxial |
| Operating Temperature Range | -52°C to +177°C (-62°F to +350°F) |
| Lineal Range | 2 mm (0 to 2 mm gap) |
| Sensitivity | 7.87 V/mm (200 mV/mil) typical |
| Linearity Error | ±0.2% of full scale |
| Target Material | Ferrous metal (4140 steel standard) |
| Supply Voltage | -24 Vdc to -26 Vdc (with proximitor) |
| Output Impedance | 50 ohms nominal |
| Inertial Resistance | 0.07 ohms per foot maximum |
| Sealing | Hermetically sealed probe tip and coil |
| Environmental Protection | NEMA 4X, IP66 rated (when properly mated) |
| Dimensions | Probe body diameter: 13.5 mm; Thread length: 18 mm; Overall length with connector: 112 mm |
| Weight (kg) | 0.18 kg (complete probe with 1m cable and connector) |
The 330104-03-18-50-02-RU is used extensively in condition monitoring and protective systems for critical rotating machinery. Typical applications include:
Radial Vibration Measurement on journal bearings of steam turbines, gas turbines, compressors, and pumps.
Axial (Thrust) Position Monitoring to detect thrust bearing wear and prevent rotor-stator rub.
Eccentricity Measurement on turbine rotors during startup and shutdown.
Differential Expansion Monitoring between rotor and casing in large steam turbines.
Shaft Phase Reference for balancing and torsional vibration analysis using keyphasor signals.
Gap Voltage Monitoring for seal and clearance control in high-speed rotating equipment.
Bearing Wear Detection through DC gap trend analysis.
Overspeed Protection Systems when used with a speed sensing proximitor.
This reverse mount configuration is particularly valuable in retrofit applications where existing probe holes do not accommodate standard side-exit cables, such as in legacy power plants, refineries, and offshore platforms.
Reverse Mount Design allows cable routing from the rear, simplifying installation in tight machine casings.
High Thermal Stability maintains consistent sensitivity across a wide temperature range without recalibration.
Hermetic Sealing prevents oil, steam, and chemical ingress, ensuring reliability in wet or corrosive environments.
Integrated Armored Cable resists abrasion, crushing, and fluid absorption, extending service life.
Interchangeability with all 3300 XL proximitors and extension cables without recalibration.
Precision Linear Range from 0 to 2 mm with industry-leading ±0.2% linearity error.
Reverse Polarity Protection built into compatible proximitors prevents damage from installation errors.
Easy Gap Setup using DC voltage output eliminates the need for micrometers in routine installations.
Failsafe Design tolerates accidental cable shorting or open circuits without damage.
Low Weight (0.18 kg) reduces mechanical stress on probe mounting brackets.
The product is manufactured under the Bently Nevada brand. Bently Nevada is the original inventor of the proximity probe and remains the global benchmark for machinery protection and condition monitoring systems. The brand is synonymous with high-reliability sensors, monitoring racks, and diagnostic software for rotating machinery.
The 330104-03-18-50-02-RU belongs to the 3300 XL 8mm Proximity Probe Series. This series includes:
3300 XL 8mm Probes (standard side exit and reverse mount)
3300 XL 8mm Extension Cables (various lengths)
3300 XL 8mm Proximitors (signal conditioners)
Key features of the 3300 XL series include superior radio frequency interference (RFI) immunity, high temperature stability, and compatibility with older 3300 and 7200 series systems via adapters.
| Model Number | Key Parameters | Weight (kg) | Dimensions (mm) |
|---|---|---|---|
| 330104-03-18-10-02-RU | 8mm reverse mount probe, 18mm unthreaded, 1.0m cable, standard connector, -52°C to +177°C | 0.18 | Probe body 13.5 dia; Thread length 18; Overall 112 |
| 330103-00-05-50-02-00 | 8mm standard side-exit probe, 5mm unthreaded, 0.5m cable, no connector (pigtail) | 0.12 | Probe body 13.5 dia; Thread length 5; Overall 75 |
| 330106-05-18-10-02-00 | 8mm high-temp probe, 18mm unthreaded, 1.0m cable, standard connector, -52°C to +200°C | 0.19 | Probe body 13.5 dia; Thread length 18; Overall 112 |
| 330101-00-24-90-02-05 | 8mm probe with 24mm unthreaded, 9.0m cable, armored, 5m extension capability | 0.85 | Probe body 13.5 dia; Cable length 9000; Thread length 24 |
| 330102-02-12-30-02-03 | 8mm reverse mount probe, 12mm unthreaded, 3.0m cable, metric thread M10x1, -52°C to +150°C | 0.42 | Probe body 13.5 dia; Thread length 12; Cable 3000 |
| Model Number | Key Parameters | Weight (kg) | Dimensions (mm) |
|---|---|---|---|
| 330180-50-00 | 3300 XL Proximitor, 8mm system, 3-wire output, -24Vdc supply, 0-10Vdc output, panel mount | 0.09 | 64 x 38 x 25 (LxWxH) |
| 330130-040-00-00 | 3300 XL Extension Cable, 4.0m length, coaxial, fluid-resistant jacket, gold-plated contacts | 0.30 | Cable diameter 4.5mm; Length 4000mm |
| 3500/42M | 4-channel Proximitor/seismic monitor module for 3500 rack, DC output, 0-10Vdc, internal relays | 0.45 | Module 241 x 38 x 220 |
| 330400-02-00 | 3300 XL Reverse mount Proximitor, -24Vdc supply, panel/DIN rail mount, RFI immune | 0.10 | 70 x 45 x 30 |
| 330195-02-12-00-00 | 3300 XL 8mm high-temperature probe assembly (probe + cable + connector), 2.0m total, -52°C to +200°C | 0.38 | Probe body 13.5 dia; Cable length 2000 |
Q1: What is the exact weight of the Bently Nevada 330104-03-18-50-02-RU including the full cable and connector?
A1: The total weight of the probe assembly is exactly 0.18 kg (180 grams). This includes the 8mm probe body, the integral 1.0 meter armored coaxial cable, and the 2-pin military style connector.
Q2: Can I use this reverse mount probe with any 3300 XL proximitor?
A2: Yes, the 330104-03-18-50-02-RU is fully compatible with all 3300 XL series proximitors, such as models 330180-50-00 and 330400-02-00. No recalibration or adjustment is needed when swapping probes within the same series.
Q3: What is the maximum allowable cable length between the probe and proximitor?
A3: The maximum total cable length (probe integral cable plus extension cable) is 9.0 meters. For this model, which has a 1.0 meter integral cable, you can add up to 8.0 meters of extension cable. Exceeding this length will cause signal degradation and loss of linearity.
Q4: How do I properly clean the probe tip without damaging it?
A4: Use only isopropyl alcohol and a soft lint-free cloth. Gently wipe the probe tip in a circular motion. Do not use abrasive materials, acetone, or high-pressure solvents, as they can damage the hermetically sealed PPS (polyphenylene sulfide) tip surface.
Q5: Is the 330104-03-18-50-02-RU suitable for underwater or submerged applications?
A5: No. Although the probe tip and cable are hermetically sealed and rated IP66, continuous submersion beyond 1 meter depth is not recommended. The probe is designed for industrial machine environments with oil mist, steam, and occasional splashing, not permanent underwater use.
Q6: What target material must be used for accurate measurements?
A6: The probe is factory calibrated for AISI 4140 steel (a ferrous material). Using non-ferrous targets like aluminum or stainless steel will change the scale factor by up to 30%. If your machine has a different target material, you must order a custom-calibrated probe or apply a correction factor.
Q7: What is the meaning of “RU” in the model number suffix?
A7: The “RU” stands for “Reverse Mount Unthreaded” configuration. This means the cable exits from the rear of the probe housing (reverse mount), and the “U” indicates the unthreaded length specification is part of the standard ordering code. This design allows the probe to fit through smaller openings.
Q8: How do I verify if my 330104-03-18-50-02-RU is damaged?
A8: Measure the DC resistance between the probe connector’s center pin and outer shield. A functional probe should read between 15 and 25 ohms at 25°C. Also check for any short to ground (infinite resistance). Any reading outside these ranges indicates cable or coil damage.
Q9: Can I cut and re-terminate the cable if it gets damaged in the field?
A9: No. The coaxial cable is precision impedance-matched to the probe coil. Cutting or re-terminating will alter the cable capacitance and impedance, destroying linearity and sensitivity. The entire probe assembly must be replaced.
Q10: What is the recommended installation torque for the probe mounting threads?
A10: Apply no more than 14 N·m (10 ft·lbs) of torque when threading the probe into a mounting block or bracket. Exceeding this torque can strip the 3/8-24 UNF threads or crack the probe body. Use a torque wrench and never use anti-seize compounds containing graphite, as they can cause electrical shorts.