21000-27-05-40-026-03-02 | Bently Nevada | Proximity ProbeHousing Assemblies

Technical Overview

The Bently Nevada 21000-27-05-40-026-03-02 is a proximity probe housing assembly designed to provide a secure, environmentally sealed, and adjustable mounting for proximity probes on industrial machinery. Its primary function is to protect the sensitive probe element from the harsh process environment (e.g., high pressure, corrosive gases, liquids) while allowing precise positioning relative to the observed machine shaft. This specific assembly is constructed from 316 Stainless Steel for superior corrosion resistance. It features a 3/4-14 NPT mounting thread for direct installation into the machine casing. The assembly houses a 3300 XL 8 mm probe, which operates on the eddy current principle. The probe, connected via an extension cable to a Proximitor Sensor, transmits a high-frequency RF signal. The proximity of the conductive shaft surface modulates this signal, which the Proximitor Sensor demodulates into a DC voltage proportional to the probe-to-shaft gap. This conditioned signal is then supplied to a Bently Nevada 3500 Machinery Protection System for continuous monitoring of radial vibration, axial position, and rotational speed.

Detailed Specifications

Operational Capabilities

In Oil & Gas and Power Generation applications, the 21000-27-05-40-026-03-02 assembly provides a robust and reliable platform for critical machinery monitoring. Its 316 Stainless Steel construction ensures long-term integrity in environments containing hydrogen sulfide (H2S), chlorides, and other corrosive agents common in refineries and offshore platforms. The NPT thread mounting, when installed with appropriate sealant, creates a high-pressure seal, preventing the escape of process gases or liquids. This is critical for safety and environmental compliance on equipment such as centrifugal compressors and high-pressure pumps. The assembly’s design facilitates stable probe gapping, which is essential for the accuracy and repeatability of vibration and position measurements required for API 670 compliant protection systems. The housing is engineered for continuous, long-term service with minimal maintenance, contributing to high machine availability and reduced lifecycle costs for critical assets like gas turbines, steam turbines, and generators.

Applications

• Power generation turbines and generators
• Oil & gas compressors and pumps
• Industrial rotating machinery monitoring
• Predictive maintenance systems
• Process automation

Technical FAQ

Q: What systems is the 21000-27-05-40-026-03-02 compatible with?
A: The 3300 XL 8 mm probe included with the 21000-27-05-40-026-03-02 assembly is part of a transducer system that requires a matching 3300 XL extension cable and a 3300 XL Proximitor Sensor. The complete transducer system output is fully compatible with Bently Nevada machinery protection and condition monitoring systems, including the 3500 Series (e.g., 3500/42M Proximitor/Seismic Monitor), 3300 Series Monitors, and ADRE data acquisition systems. The housing’s 3/4-14 NPT mechanical interface is compatible with any machine case drilled and tapped to this standard thread size.

Q: What are the installation requirements?
A: Installation requires a 3/4-14 NPT tapped hole at the measurement location on the machine casing. An appropriate thread sealant (e.g., PTFE tape or pipe dope compatible with the process fluid and temperature) must be applied to the mounting threads to ensure a pressure-tight seal. The probe must be gapped by adjusting its position within the housing to achieve the correct DC voltage output (typically -10.0 Vdc for a 3300 XL 8 mm system) when measured at the Proximitor Sensor’s output terminals. After gapping, the probe is secured in place using the housing’s set screws. Adherence to Bently Nevada’s specified torque values for the housing and any fittings is mandatory to prevent damage and ensure seal integrity.