Bently Nevada 21000 Series Modules

Technical Dossier

Product Details And Specifications

Bently Nevada 21000 Series: Comprehensive Module Range and Technical Overview

The Bently Nevada 21000 Series is a proximity transducer system engineered for continuous, non-contact measurement of shaft radial vibration, axial position, and differential expansion in rotating machinery. Deployed across petrochemical refineries, nuclear power stations, offshore platforms, and heavy industrial compressor trains, the 21000 Series represents one of the most widely installed eddy-current probe systems in the global machinery protection market. Its 5 mm and 8 mm probe formats, combined with standardized extension cable and driver/oscillator electronics, established the wiring and calibration conventions that subsequent Bently Nevada generations—including the 3300 XL and 330100 series—were designed to be backward-compatible with. Installed base density in critical turbomachinery applications means that 21000 Series components remain in active service at facilities with 20–40 year asset lifecycles, making spare parts availability a direct operational risk factor.

The Evolution of 21000 Series Architecture

The 21000 Series was introduced as part of Bently Nevada's first-generation eddy-current proximity system, predating the transition to the 3300 platform. The core architecture consists of three elements: the probe (sensing element), the extension cable (signal transmission), and the driver/oscillator (signal conditioning). Each element is length-matched and calibrated as a system; substituting components from different series without recalibration introduces measurement error.

Early 21000 variants used a 200 mV/mil (7.87 V/mm) output scale factor, which became the de facto standard for Bently Nevada-compatible monitor inputs. The 3300 XL series introduced the 100 mV/mil (3.937 V/mm) scale factor as an alternative, creating a compatibility boundary that maintenance engineers must verify before substitution. The 21000 Series probes are rated for operating temperatures from -35°C to +177°C at the probe tip, with extension cables rated to +105°C continuous. Driver/oscillators require a regulated -24 VDC supply (±1 VDC) and produce a DC output proportional to gap distance, typically calibrated over a 0–80 mil (0–2.032 mm) linear range for radial vibration applications.

As of the mid-2000s, Bently Nevada (a Baker Hughes company) formally transitioned new installations to the 3300 XL and 330100 series. The 21000 Series entered end-of-life status, with OEM production discontinued. However, the installed base in legacy DCS and machinery protection systems—particularly those integrated with 3500 Series rack monitors via 21000-compatible transducer inputs—sustains demand for certified replacement and repair inventory.

21000 Series Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced components within the 21000 Series ecosystem. Classifications follow functional role within the transducer system.

Probes (Sensing Elements)

• 21000-00-05-10-02-00: 5 mm probe, 0.5 m integral cable, standard temperature, radial vibration measurement
• 21000-00-08-10-02-00: 8 mm probe, 0.5 m integral cable, standard temperature, radial/axial measurement
• 21000-00-05-10-02-01: 5 mm probe, 0.5 m integral cable, high-temperature variant, up to +177°C tip
• 21000-00-08-10-02-01: 8 mm probe, 0.5 m integral cable, high-temperature variant, petrochemical service
• 21000-00-05-10-05-00: 5 mm probe, 5 m integral cable, standard temperature, extended reach installation
• 21000-00-08-10-05-00: 8 mm probe, 5 m integral cable, standard temperature, compressor train applications

Extension Cables

• 21000-01-05-05: 5 mm system extension cable, 5 m, armored jacket, standard temperature
• 21000-01-05-10: 5 mm system extension cable, 10 m, armored jacket, standard temperature
• 21000-01-08-05: 8 mm system extension cable, 5 m, armored jacket, standard temperature
• 21000-01-08-10: 8 mm system extension cable, 10 m, armored jacket, standard temperature

Driver/Oscillators (Signal Conditioners)

• 21000-02-05-05: 5 mm driver/oscillator, DIN rail mount, -24 VDC input, 200 mV/mil output
• 21000-02-08-05: 8 mm driver/oscillator, DIN rail mount, -24 VDC input, 200 mV/mil output
• 21000-02-05-10: 5 mm driver/oscillator, panel mount, extended cable system compatible

Probe Housing & Mechanical Assemblies

• 21000-16-10-15-098-03-02: Probe housing assembly, 10 m system, 15 mm thread, stainless steel body, standard configuration
• 21000-16-10-15-098-03-01: Probe housing assembly, 10 m system, 15 mm thread, high-temperature configuration
• 21000-16-05-15-098-03-02: Probe housing assembly, 5 m system, 15 mm thread, standard configuration

Sourcing Hard-to-Find & Obsolete 21000 Series Parts

DriveKNMS maintains a dedicated inventory program for end-of-life Bently Nevada 21000 Series components. Because OEM production has ceased, sourcing strategies for this series require access to certified surplus stock, refurbished units with documented test records, and cross-reference mapping to compatible 3300 XL or 330100 replacements where system recalibration is feasible.

DriveKNMS sources 21000 Series inventory through decommissioned plant asset recovery, authorized surplus channels, and direct procurement from facilities undergoing DCS upgrades. Each unit entering inventory is assigned a condition grade (New Surplus, Refurbished, or Tested Used) with full traceability documentation. For facilities that cannot undertake a full transducer system upgrade—due to shutdown scheduling constraints, capital budget cycles, or regulatory hold points—DriveKNMS provides like-for-like replacement units that maintain the original calibration scale factor and connector configuration, eliminating the need for monitor reconfiguration.

Quality Control for the 21000 Series Range

The 21000 Series presents specific verification requirements due to the matched-system calibration dependency between probe, extension cable, and driver/oscillator. DriveKNMS applies the following test protocol to all 21000 Series units prior to dispatch:

• Gap voltage linearity test: Each probe-cable-driver assembly is tested against a calibrated target (AISI 4140 steel) across the full 0–80 mil range. Output linearity must be within ±1% of the 200 mV/mil scale factor.
• Insulation resistance verification: Extension cable shield and center conductor insulation resistance tested at 500 VDC; minimum 100 MΩ required.
• Connector integrity inspection: All coaxial connectors inspected for pin straightness, dielectric condition, and shell thread engagement. Connectors showing corrosion or mechanical deformation are replaced before testing.
• Driver/oscillator supply current and output noise: Supply current draw verified within OEM specification; output noise floor measured with spectrum analyzer to confirm absence of oscillator instability.
• Thermal cycling (refurbished units): Refurbished driver/oscillators undergo 10-cycle thermal stress from -20°C to +70°C with functional verification at each extreme.

Test records are provided with each shipment. Units that do not pass all criteria are quarantined and not released for sale.

© 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.