Bently Nevada 21504-16-32-10-62 7200 Series 5 mm and 8 mm Standard Mount Probe

Description

Option 16 (1.6 in unthreaded length) and Option 62 (miniature male coaxial connector with connector protector) specify this 7200 Series proximity probe configuration — 21504-16-32-10-62.

This non-contact eddy-current sensor is used for shaft vibration and axial position measurement on rotating and reciprocating machinery. The 21504-16-32-10-62 features an 8 mm tip constructed of polyphenylene sulfide (PPS), a high-performance plastic capable of withstanding harsh, wet, and chemical environments. It operates on the eddy current principle to sense static and dynamic distances between the probe tip and the observed target (typically an AISI 4140 steel target). This probe is designed without stainless steel lead armor (unarmored) and has a 3/8-24 UNF-2A standard English thread. Unlike its armored sibling, the 21505, this unarmored variant utilizes a standard 95 ohm coaxial cable with a total length of 1.0 m (Option 10) and is equipped with a connector protector (Option 62) to prevent debris and moisture ingress at the connection point.

Features

• 8 mm tip diameter constructed of polyphenylene sulfide (PPS) for chemical, moisture, and corrosion resistance.
• 3/8-24 UNF-2A threaded case with 1.6 inches unthreaded length and 3.2 inches overall case length.
• 1.0 m (39 inches) integral 95 ohm coaxial cable (Option 10) with miniature male coaxial connector and connector protector (Option 62).
• Unarmored coaxial cable layout for routing in standard conduit and internal machine brackets.
• 80 mils (2.0 mm) linear measuring range when paired with a compatible 7200 Proximitor and target.
• Frequency response from 0 Hz (DC) to 10 kHz (-5% at 10 kHz) for high-speed dynamic measurements.
• Operational temperature range of -30 degF to +350 degF (-34 degC to +177 degC) for the probe tip and cable assembly.

Applications

• Shaft radial vibration monitoring for rotor dynamic analysis and bearing wear detection.
• Axial thrust position measurement to monitor thrust bearing condition and prevent critical failures.
• Shaft average radial position determination for attitude angle and rotor stability checks.
• Rotor eccentricity and bow measurements during machine startup/shutdown.
• Speed and phase reference (Keyphasor) sensing on steam turbines, gas turbines, compressors, pumps, and generators.

Ordering Information

Technical Specifications

Connections and Interfaces

The integrated coaxial cable terminates in a miniature male coaxial connector equipped with a connector protector. This interface connects to the female coaxial connector on a 7200 Series extension cable or Proximitor sensor. This coaxial connection is designed with a 95 ohm impedance to prevent signal reflections and maintain system calibration.

Installation Guidelines

• Grounding: Coaxial shielding must be maintained and insulated from the machine casing.
• Probe gap adjustment: Typically set to the center of the linear range (approx. 50 mils or 1.27 mm) using a voltmeter to measure the Proximitor output (typically -10 Vdc at mid-gap).
• Cable routing: Avoid routing coaxial cables alongside high-voltage AC lines. Secure cable to prevent whipping or abrasion.
• Wrench flats: Use the 7/16-inch hex case threads and jam nuts for standard mounting.
• Clearance: Ensure adequate side clearance around the probe tip (typically a minimum diameter of 1.2 inches / 30.5 mm of open space) to prevent side-loading/cross-talk from adjacent metal.