Bently Nevada 24701 Series Modules

Technical Dossier

Product Details And Specifications

Bently Nevada 24701 Series: Comprehensive Module Range and Technical Overview

The Bently Nevada 24701 Series represents one of the most widely deployed proximity transducer system families in global heavy industry. Installed across petrochemical refineries, nuclear power stations, offshore platforms, and large-scale chemical processing facilities, the 24701 Series forms the sensing backbone of rotating machinery protection systems operating under API 670 standards. Its primary function is continuous, non-contact measurement of shaft radial vibration, axial position, and differential expansion — parameters that are critical to turbine, compressor, and pump protection in continuous-process environments where unplanned downtime carries multi-million-dollar consequences.

The 24701 Series is engineered for integration with Bently Nevada's 3300, 3500, and ADAPT.wind monitoring platforms, and remains in active use at facilities where system replacement is constrained by capital expenditure cycles or regulatory freeze requirements. The installed base of this series spans over four decades of industrial deployment, making reliable spare parts availability a primary operational concern for maintenance engineers worldwide.

The Evolution of 24701 Series Architecture

The 24701 Series was introduced as part of Bently Nevada's second-generation proximity transducer system architecture, succeeding the earlier 7200 Series. The design philosophy centered on a three-component system: the probe tip, the extension cable, and the proximitor (signal conditioning module). This triaxial architecture allowed field replacement of individual components without disturbing the entire measurement loop — a significant operational advantage in continuous-process plants.

Early Generation (1980s–1990s): Initial 24701 variants used a 5-meter standard cable system with fixed-gap calibration. These units were factory-matched to specific proximitor models and were not interchangeable across series without recalibration. The probe tip diameter was standardized at 8mm, targeting shaft materials with a relative magnetic permeability of 1.0 (AISI 4140 steel reference standard).

Mid-Generation Refinement (1990s–2000s): Bently Nevada introduced extended-temperature variants and armored cable assemblies to address installation environments in high-vibration, high-temperature zones adjacent to steam turbine casings. The proximitor electronics were revised to improve EMI rejection, addressing interference issues identified in early nuclear plant deployments.

Transition to 3300 XL and 3500 Platform Compatibility (2000s–2010s): As the 3500 Series machinery protection system became the dominant platform, 24701 probes were validated for use with 3500/40M, 3500/42M, and 3500/46M monitor modules. This cross-platform compatibility extended the operational life of existing 24701 probe installations while facilities upgraded their rack-level electronics.

Current Status — Mature/End-of-Life Phase: Baker Hughes (the current owner of the Bently Nevada brand) has transitioned primary development to the 3300 XL 8mm and Velomitor series. The 24701 Series is classified as a mature product line. New production runs are limited. For facilities maintaining 24701-based systems, long-term maintenance support through authorized distributors and specialist spare parts suppliers is the primary procurement strategy. DriveKNMS maintains dedicated inventory of 24701 Series components to support lifecycle extension programs.

24701 Series Full Catalog & Functionalities (SKU List)

The following SKUs represent the core 24701 Series product range, organized by functional category. All models listed are verified members of the Bently Nevada 24701 proximity transducer system family.

Proximity Probe Assemblies

24701-28-10-00-040-00-02: 8mm proximity probe, 40cm armored cable, standard temperature housing assembly, API 670 compliant.

24701-28-10-00-100-00-02: 8mm proximity probe, 100cm armored cable, extended-reach housing assembly for deep-bore installations.

24701-28-10-00-200-00-02: 8mm proximity probe, 200cm armored cable, long-extension configuration for large-frame turbine casings.

24701-28-10-00-040-00-01: 8mm proximity probe, 40cm cable, standard housing, metric connector variant for European plant installations.

24701-28-10-00-100-00-01: 8mm proximity probe, 100cm cable, metric connector, extended-reach variant.

Extension Cable Assemblies

24701-50-00-01-00: 5-meter coaxial extension cable, standard impedance, for use with 24701 probe and 3300/3500 proximitor systems.

24701-50-00-02-00: 9-meter coaxial extension cable, armored jacket, for installations requiring increased probe-to-proximitor separation distance.

24701-50-00-05-00: 5-meter extension cable, high-temperature rated jacket (up to 150°C), for turbine pedestal installations.

24701-50-00-09-00: 9-meter extension cable, high-temperature rated, armored, for combined thermal and mechanical stress environments.

Proximitor Signal Conditioners

24701-00-00-05-00: Standard proximitor module, -24 VDC supply, 200 mV/mil output sensitivity, for 3300 Series rack integration.

24701-00-00-09-00: Extended-range proximitor, -24 VDC, 200 mV/mil, for 9-meter cable system configurations.

24701-00-00-05-02: Proximitor module, -24 VDC, 200 mV/mil, with integral EMI shielding for high-interference environments (switchgear rooms, motor control centers).

24701-00-00-09-02: Extended-range proximitor with EMI shielding, 9-meter cable system compatible.

Housing & Mounting Hardware

24701-28-10-00-040-00-02-HT: High-temperature probe housing assembly, 40cm cable, rated for continuous operation at 175°C ambient.

24701-28-10-00-040-00-02-EX: ATEX/IECEx certified probe housing assembly, 40cm cable, for Zone 1 hazardous area installations in petrochemical facilities.

24701-28-10-00-040-00-02-SS: Stainless steel housing variant, 40cm cable, for corrosive atmosphere installations (offshore, coastal chemical plants).

Sourcing Hard-to-Find & Obsolete 24701 Series Parts

As the 24701 Series has entered its mature and end-of-life phase, procurement of specific SKUs through standard distribution channels has become increasingly unreliable. Baker Hughes / Bently Nevada no longer guarantees stock availability for all 24701 variants, and lead times through OEM channels can extend to 16–26 weeks for low-volume SKUs.

DriveKNMS operates a dedicated lifecycle support program for the 24701 Series, addressing the following procurement scenarios:

New Old Stock (NOS): DriveKNMS maintains warehouse inventory of factory-sealed 24701 Series components sourced from decommissioned plant inventories and authorized distributor closeouts. NOS units are supplied with original manufacturer documentation and date codes.

Reconditioned Units: For SKUs where NOS stock is exhausted, DriveKNMS offers factory-equivalent reconditioned units. Each reconditioned 24701 component undergoes full disassembly, component-level inspection, and functional restoration before retest against original Bently Nevada performance specifications.

Cross-Reference and Substitution: Where a specific 24701 SKU is confirmed obsolete with no available stock, DriveKNMS engineering staff can identify validated substitute SKUs from the Bently Nevada 3300 XL 8mm Series or third-party API 670-compliant alternatives, with full documentation of the substitution rationale for plant engineering records.

Emergency Supply: DriveKNMS maintains a priority fulfillment channel for unplanned outage scenarios. Emergency orders for 24701 Series components are processed within 24 hours of inquiry confirmation, with air freight dispatch to minimize machinery downtime.

Quality Control for the 24701 Series Range

The 24701 Series presents specific quality verification challenges due to the precision nature of proximity measurement and the sensitivity of the triaxial system to component-level variation. DriveKNMS applies the following test protocols to all 24701 Series inventory prior to dispatch:

Gap Voltage Verification: Each probe-cable-proximitor assembly is tested as a matched system on a calibrated steel target (AISI 4140, 1.0 relative permeability). Gap voltage is measured at 0.25mm increments across the full linear range (typically 0.25mm to 2.25mm) and compared against the Bently Nevada factory calibration curve. Units with deviation exceeding ±1% of full-scale output are rejected.

Cable Impedance and Continuity: Extension cables are tested for coaxial impedance (nominal 95Ω), center conductor continuity, and shield integrity. Cables with impedance deviation greater than ±5Ω or any measurable shield-to-conductor leakage are rejected.

Proximitor Supply Current and Output Linearity: Proximitor modules are powered at -24 VDC and tested for supply current draw (nominal 25–35 mA), output voltage linearity across the calibrated gap range, and output noise floor (must be below 5 mV RMS at 10 kHz bandwidth).

High-Temperature Soak Test: High-temperature and ATEX-rated variants are subjected to a 4-hour thermal soak at rated maximum temperature before functional retest. This identifies latent failures in cable jacket materials and connector seals that would not be detected at ambient temperature.

Documentation Package: Each dispatched unit is accompanied by a test report, date code record, and (where applicable) original manufacturer calibration certificate. This documentation supports plant quality management system requirements and regulatory audit trails.

© 2026 DriveKNMS. All trademarks belong to their respective owners. Specifications are for reference only and subject to change without notice. Verify all parameters against official documentation before installation.