The 146055-10-02-05 is a specialised non‑contact eddy‑current proximity probe from the Bently Nevada 3300 series, engineered for machinery monitoring applications that demand a reverse‑mount configuration. This model is a 3300 Ceramic Capped Reverse Mount Probe featuring a standard imperial 3/8‑24 UNF mounting thread, a 1.0‑metre total integral cable, a miniature coaxial ClickLoc connector with standard cable, and multiple hazardous area approvals (CSA, ATEX, IECEx). The reverse‑mount design is specifically intended for use in Bently Nevada 31000 and 21000 series housings, as well as other custom enclosures where the probe must be installed from the inside or where space constraints dictate a rear‑entry mounting approach. The 1.0‑metre cable length provides additional routing flexibility compared to the 0.5‑metre variant, allowing the Proximitor Sensor to be placed at a more convenient distance while still maintaining short‑cable performance.
The ceramic‑capped tip is the hallmark of this probe family. The sensing face is fabricated from high‑purity alumina (Al₂O₃), which provides exceptional chemical inertness, high dielectric strength, and superior hardness. This ceramic material resists corrosion from anhydrous ammonia, hydrogen sulphide, caustic solutions, acidic vapours, and a wide range of organic solvents that would rapidly degrade conventional polymer‑tipped or unprotected metal‑tipped probes. The probe case is manufactured from AISI 304 stainless steel, offering robust mechanical protection and excellent resistance to pitting, crevice corrosion, and oxidation in humid, saline, or chemically active atmospheres. The front‑end ceramic‑to‑metal interface is hermetically sealed and helium leak‑tested at the factory, ensuring that corrosive gases and liquids cannot penetrate the internal sensing coil cavity – a critical requirement for long‑term reliability in harsh service.
The 146055-10-02-05 is designed for applications where only the front portion of the probe case assembly is exposed to corrosive media, but with the distinct difference that the probe is mounted in a reverse orientation compared to standard forward‑mount probes. In a reverse‑mount configuration, the probe is inserted from the back of the housing, with the tip extending toward the shaft. This geometry is often required in bearing housings, thrust bearing compartments, or other confined spaces where a forward‑mount probe cannot be easily inserted or where the housing design dictates a rearward installation. The reverse‑mount probe features a different mechanical profile: it has 7/16‑inch wrench flats instead of the 5/16‑inch flats found on forward‑mount probes, and the mounting threads are positioned closer to the tip end. The overall length is fixed and defined by the total cable length option; there is no separate case length adjustment.
It is important to note that the 146055-10-02-05 shares the same fundamental limitation as the 146054 forward‑mount probes: it does not include a rear fitting or stainless steel tubing. Consequently, the rear of the probe – where the coaxial cable exits the case – is not sealed and must be protected from water, ammonia, ammonium hydroxide, hydrogen sulphide, or any corrosive environment. The rear cable exit must be routed through a clean, dry, non‑corrosive zone. For applications requiring full front‑and‑rear sealing, the 146056 variant with rear tubing and NPT fittings is the recommended alternative, but that model is not available in reverse‑mount configuration.
The 146055-10-02-05 has a total cable length of 1.0 metre (3.3 feet). This moderate length is typical for reverse‑mount applications where the Proximitor Sensor is located near the machine but requires some distance for convenient mounting, such as on a nearby junction box or machine frame. The probe is supplied with a standard miniature coaxial ClickLoc connector (option 02) without a connector protector; however, connector protectors can be added as field‑installed accessories. The probe is not available with armour or with a connector protector pre‑installed, as noted in the datasheet. The -05 approval option signifies that the probe carries multiple international hazardous area certifications, making it suitable for installation in explosive atmospheres worldwide.
When combined with a 3300 Proximitor Sensor and a matching extension cable (typically of complementary length), the 146055-10-02-05 forms a complete transducer system for measuring shaft relative vibration, axial position (thrust), eccentricity, and rotational speed in applications where reverse mounting is mechanically advantageous. The system is factory‑calibrated to an AISI 4140 steel target and exhibits a linear range of 1.52 mm (60 mils) with a nominal scale factor of 7.87 V/mm (200 mV/mil). Its interchangeability error of ±6.5 % ensures that replacement components can be fitted without full system recalibration, reducing maintenance downtime.
Construction and Design Features
The 146055-10-02-05 is mechanically distinct from its forward‑mount counterparts. The reverse‑mount configuration is optimised for installation in housings that have limited access from the front or where the probe must be secured from the rear. The probe case is machined from AISI 304 stainless steel and features a 3/8‑24 UNF 2A thread, but the thread position relative to the tip differs from forward‑mount probes. The wrench flats are 7/16‑inch (11.1 mm) across, providing a larger gripping surface for torque application during installation. The case length is not user‑selectable; instead, the total length (from tip to connector) is determined solely by the cable length option, which for this model is 1.0 metre.
The ceramic tip is identical in material and construction to other 3300 ceramic‑capped probes: high‑purity alumina, brazed to the stainless steel case to form a hermetic seal. The tip diameter is 7.0 mm (0.273 inch), and the threaded section diameter is 7.2 mm (0.285 inch). The probe is designed for use in 31000 or 21000 housings, as indicated in the datasheet, but can also be adapted to other housings with compatible thread and clearance requirements. Reverse‑mount probes are not available with armour or connector protector options, which is explicitly noted in the datasheet. Therefore, the 146055-10-02-05 is supplied without these additional protections.
The integral coaxial cable is 1.0 metre in length and uses a 75 Ω impedance design with fluorinated ethylene propylene (FEP) insulation. FEP provides excellent dielectric properties, low moisture absorption, and resistance to high temperatures and chemicals. The cable is terminated with a miniature coaxial ClickLoc connector, which is gold‑plated to resist corrosion and ensure low contact resistance. The connector's positive locking mechanism audibly "clicks" when finger‑tight, eliminating the need for tools and preventing accidental disconnection due to vibration. The connector is of the standard fixed‑nut type (option 02), and a removable‑nut version is not offered for this model.
Because the rear of the probe is not sealed, the cable exit must be protected from the environment. In reverse‑mount installations, the cable typically exits through the rear of the housing and is routed to a junction box. Care must be taken to ensure that any moisture or corrosive vapour does not track along the cable and enter the probe rear. The use of connector protectors (accessories) is strongly recommended for all installations to provide increased environmental protection, even though they are not pre‑installed.
Intended Applications
The 146055-10-02-05 is ideally suited for the following industrial environments and machinery types, particularly where reverse mounting is required and a 1.0‑metre cable provides the right reach:
Bently Nevada 31000 and 21000 series bearing housings, which are specifically designed to accommodate reverse‑mount probes. These housings are commonly used in large turbines, compressors, and pumps.
Thrust bearing compartments where the shaft is accessible only from the rear, and a forward‑mount probe cannot be installed without disassembling the machine.
Confined spaces within machinery casings where the mounting boss is located on the inside, requiring the probe to be inserted from the interior side.
Retrofitting legacy equipment that originally used reverse‑mount probes, allowing direct replacement without modifying the housing.
Applications where the Proximitor Sensor is mounted on a nearby bracket or junction box, requiring a 1.0‑metre cable for convenient connection without excessive slack.
Environments where only the front of the probe is exposed to corrosive media, and the rear cable exit can be kept in a clean, dry area.
In all these cases, the ceramic cap ensures that the sensing face remains chemically intact, while the 304 stainless steel case provides structural integrity. The 3/8‑24 thread is compatible with many existing mounting holes, and the reverse‑mount geometry simplifies installation in specific housing designs. The 1.0‑metre cable offers a good balance between routing flexibility and maintaining low cable capacitance, which is important for system accuracy.
Ordering Code Breakdown
The full product number 146055-10-02-05 is decoded as follows:
Code Segment | Value | Meaning |
Base | 146055 | 3300 Ceramic Capped Reverse Mount Probe, 3/8‑24 UNF thread |
-A (Total Length) | 10 | Total cable length = 1.0 metre (3.3 feet) |
-B (Connector) | 02 | Miniature ClickLoc coaxial connector, standard cable (no connector protector) |
-C (Agency Approval) | 05 | Multiple approvals: CSA, ATEX, IECEx |
When placing an order, the complete string 146055-10-02-05 must be used to ensure the correct combination of cable length, connector style, and certification package is delivered.
Installation and Gapping Recommendations
Correct installation of the 146055-10-02-05 is critical for reliable operation. Being a reverse‑mount probe, the installation procedure differs from forward‑mount probes. The probe is inserted from the inside of the housing or from the rear, with the threaded portion engaging a matching tapped hole. The 7/16‑inch wrench flats allow controlled torque application. It is essential to avoid over‑tightening, and the use of a lock nut (e.g., accessory 04301007 for 3/8‑24 threads) is recommended to prevent loosening due to vibration.
The gap setting follows the same electrical method as other ceramic‑capped probes. Because the linear range is shifted compared with standard 3300 XL probes, mechanical gap setting using feeler gauges is not recommended. Instead, connect the probe to the Proximitor Sensor and a power supply, and monitor the output DC voltage. Position the probe so that the target (shaft surface) falls within the linear voltage range of –4 Vdc to –16 Vdc. The optimal mid‑gap point is approximately –10 Vdc, which allows maximum bidirectional excursion for vibration measurement. The installer must ensure that the ceramic tip never contacts the rotating shaft, as the alumina is brittle and will chip or fracture upon impact. Such damage is not covered by the warranty.
The 1.0‑metre cable must be routed with a bending radius of at least 25.4 mm (1.0 inch) at every point. Sharp bends can deform the coaxial dielectric, altering capacitance and causing measurement errors. The cable length is moderate, allowing some flexibility in positioning the Proximitor Sensor, but care should still be taken to avoid strain on the cable‑to‑probe junction.
The rear of the probe is not sealed; therefore, the cable exit must be kept in a clean, dry, non‑corrosive area. In reverse‑mount installations, the cable typically exits through the rear of the housing and may pass through a conduit or cable gland. Ensure that any openings are sealed to prevent moisture or corrosive vapours from entering and tracking along the cable. The use of connector protectors (accessories) is strongly recommended to protect the connector interface from environmental contamination.
System Calibration and Target Material Considerations
The 3300 system, including the 146055-10-02-05, is factory‑calibrated using an AISI 4140 steel target. If the machine shaft is made of a different alloy (e.g., 304 stainless steel, Inconel, titanium), the scale factor and linearity will shift. Bentley Nevada offers custom calibration for non‑standard target materials – specify the material when ordering.
The interchangeability error of ±6.5 % allows field replacement of the probe, extension cable, or Proximitor Sensor without full recalibration, provided all components are from the same system family and the target material remains unchanged. For critical protection applications, perform an in‑situ verification of the gap‑to‑voltage relationship using a calibrated micrometer or dial gauge after installation.
Hazardous Area Approvals and Conditions of Safe Use
The 146055-10-02-05 with approval option -05 is certified for use in explosive atmospheres under multiple international standards. The following certifications are applicable:
CSA (cNRTLus): Intrinsic safety (ia) for Class I, Zone 0; AEx/Ex ia IIC T4/T5 Ga; also Class I, Groups A, B, C, D; Class II, Groups E, F, G; Class III. For Zone 2, non‑incendive (nA/ec) ratings are provided. Temperature classification T5 for ambient –55°C to +40°C and T4 for –55°C to +80°C.
ATEX: II 1 G; Ex ia IIC T5…T1 Ga; also Ex ia IIIC T90°C … T280°C Dc for dust atmospheres (EPL Dc).
IECEx: Ex ia IIC T5…T1 Ga; Ex nA/ec IIC T5…T1 Gc.
The entity parameters for intrinsic safety (ia) are summarised below:
Entity Parameter | Value |
Ui (maximum input voltage) | –28 V |
Ii (maximum input current) | 140 mA |
Pi (maximum input power) | 0.91 W |
Ci (internal capacitance) | 1.5 nF |
Li (internal inductance) | 610 µH |
These parameters apply when the probe is connected via Bently Nevada extension cables to a Bently Nevada Proximitor Sensor with compatible entity ratings.
The conditions of safe use, as specified in the certificates, are as follows:
For ia installations, the probe must be installed in accordance with Bently Nevada drawing 141092.
For nA / ec (Zone 2) installations, the Proximitor must be installed such that its terminals achieve a degree of protection of at least IP54, per drawing 140979.
The temperature schedule (see table below) must be observed to ensure that the probe's surface temperature does not exceed the ignition temperature of the surrounding gas or dust atmosphere.
Temperature Schedule for Hazardous Areas (Probe Only)
Temperature Class | Ambient Temperature Range (Probe Only) | Applicable EPL |
T1 | –55°C to +232°C | Ga, Gc |
T2 | –55°C to +177°C | Ga, Gc |
T3 | –55°C to +120°C | Ga, Gc |
T4 | –55°C to +80°C | Ga, Gc |
T5 | –55°C to +40°C | Ga, Gc |
T280°C (Dc) | –55°C to +232°C | Dc (dust) |
T225°C (Dc) | –55°C to +177°C | Dc |
T170°C (Dc) | –55°C to +120°C | Dc |
T130°C (Dc) | –55°C to +80°C | Dc |
T105°C (Dc) | –55°C to +100°C | Dc |
T90°C (Dc) | –55°C to +40°C | Dc |
The 146055-10-02-05 itself does not generate significant self‑heating; the temperature class is primarily determined by the maximum ambient temperature at the installation site.
Important Limitations and Critical Warnings
Users of the 146055-10-02-05 must strictly observe the following limitations to ensure safe and reliable operation.
The rear of the probe is not hermetically sealed. Exposure of the cable exit or the rear portion of the probe case to any liquid (water, ammonia, condensate), corrosive gas (hydrogen sulphide, chlorine), or caustic vapour will lead to rapid degradation of the FEP insulation, corrosion of the centre conductor, and eventual electrical failure. This is the single most important operational constraint for this model. The rear cable exit must be routed through a clean, dry, non‑corrosive area at all times.
The ceramic tip is chemically robust but mechanically fragile. Any direct contact with the rotating shaft during installation, maintenance, or machine transient conditions can cause chipping, cracking, or complete fracture of the alumina cap. Such damage is catastrophic to measurement accuracy and is not covered by the product warranty. The probe must be gapped electrically, and physical stops must be used with extreme care.
The pressure rating of 34 Bar (500 psi) applies only to the front‑end ceramic‑to‑metal seal. It does not imply that the entire probe body can withstand differential pressure across the mounting thread. If the process pressure exceeds this value, custom engineering modifications are required – contact Bentley Nevada for assistance.
Thread engagement must not exceed 0.563 inch (14.3 mm). The internal threads of the mounting hole must conform to the appropriate fit class. If the mounting hole is deeper than this, a thread spacer or lock nut must be used to limit insertion depth. Bentley Nevada does not replace probes under warranty for damage caused by excessive thread engagement.
The cable bend radius must be maintained at or above 25.4 mm (1.0 inch). Smaller radii will deform the dielectric and change the characteristic impedance, introducing measurement errors and potentially causing intermittent signal dropout.
For installations in hazardous areas, the temperature limits and entity parameters must be respected. The probe must only be used with approved intrinsically safe barriers or isolated power supplies that limit voltage, current, and power to the specified values.
Reverse‑mount probes (like the 146055) are not available with armour or connector protector options – this is explicitly stated in the datasheet. If additional mechanical protection is required, consider using a forward‑mount probe with armour or adding external cable protection separately. Also, the 146055-10-02-05 has a 1.0‑metre cable; ensure that the Proximitor Sensor is located within a reasonable distance, and if using extension cables, match the total length appropriately to maintain system calibration. Note that 1.0‑metre probes are designed for use with matching 1.0‑metre Proximitor Sensors – mixing cable lengths may affect system accuracy.
Accessories and Complementary Products
The 146055-10-02-05 is supplied without connector protectors or armour, but connector protectors can be added as field‑installed accessories to enhance environmental protection. The following table lists commonly ordered accessories.
Accessory Part Number | Description |
40113‑02 | Connector Protector Kit for probes and extension cables; includes installation tools. Note: the female protector (03800001) must be ordered separately. |
136536‑01 | Connector Protector Adapter – allows use of pre‑1998 installation tools with modern 75 Ω ClickLoc connectors. |
03839410 | 75 Ω Triaxial Male Connector Protector – installed onto the extension cable and mates with the female connector protector on the probe. |
03800001 | 75 Ω Coaxial Female Connector Protector – installed onto the probe lead; also used on extension cables to protect the connection to the Proximitor Sensor. |
04301007 | 3/8‑24 Probe Lock Nut with safety wire holes – secures the probe in position and prevents loosening due to vibration. |
Bently_Manuals | Customer DVD containing all Bently Nevada manuals, application notes, firmware, and installation guides in multiple languages. |
Armour is not available for reverse‑mount probes; therefore, no armour accessory is listed for the 146055.
The 146055-10-02-05 is the reverse‑mount counterpart to the forward‑mount 146054 series, with a 1.0‑metre cable length. The key differences are:
Mounting orientation: Reverse‑mount probes are installed from the rear of the housing, while forward‑mount probes are installed from the front.
Wrench flats: 146055 uses 7/16‑inch flats; 146054 uses 5/16‑inch flats.
Case length: The 146054 has a user‑selectable case length (0.8 to 4.0 inches), while the 146055 does not have a separate case length option – the total length is determined solely by the cable length.
Armour and connector protector: The 146055 does not offer armour or connector protector options, whereas the 146054 can be ordered with both.
Suitable housings: The 146055 is specifically designed for 31000 and 21000 housings; the 146054 is a general‑purpose forward‑mount probe.
Compared with the 146055-05-02-05 (0.5 m cable) and 146055-20-02-05 (2.0 m cable), the 146055-10-02-05 offers a mid‑range cable length that balances routing convenience with low capacitance. The 1.0‑metre length is often chosen when the Proximitor Sensor is mounted on a nearby bracket but not immediately adjacent to the probe.
