21504-00-20-10-02 Bently Nevada 8mm Standard Mount Proximity Probe

Product Overview

The 21504-00-20-10-02 standard mount proximity probe represents the industry benchmark for non-contacting vibration, position, and keyphasor measurements. Engineered by Bently Nevada for critical machinery protection, this 8 mm diameter probe delivers precise shaft displacement monitoring in high-velocity turbomachinery, pumps, and compressors across petrochemical refineries, gas turbine power plants, and heavy mining facilities. By transmitting high-frequency eddy current signals to a proximitor sensor, it continuously evaluates dynamic motion and static gap distance, enabling operators to detect shaft misalignment, unbalance, and bearing wear before catastrophic failures occur. This rugged hardware minimizes unplanned outages and optimizes asset lifecycle management in extreme industrial environments.

Suffix Breakdown

The model code 21504-00-20-10-02 specifies a highly tailored mechanical and electrical configuration:

• 21504: Base model number for the standard mount 8 mm proximity probe with 3/8-24 UNF thread.

• 00: Unthreaded Length Option specifying 0.0 inches of unthreaded body (fully threaded case).

• 20: Overall Case Length Option denoting 2.0 inches of overall probe case length.

• 10: Total Length Option representing 1.0 metre total cable length. (Tolerance: +0.25 metre, -0.10 metre).

• 02: Connector Option equipped with a miniature male coaxial connector.

Technical Specifications

Technical FAQs

• Q: How is the physical gap voltage calibrated during commission of the 21504-00-20-10-02 probe?

  A: Mechanical calibration relies on monitoring the DC gap voltage output from the associated Proximitor. Position the probe face relative to the target shaft until the voltmeter reads approximately -10.0 VDC (the nominal midpoint of the linear 80 mil calibration range) before tightening the mounting locknuts.

• Q: Does this model include stainless steel armor for physical cable protection?

  A: No, the "02" connector suffix and the standard 21504 base option denote a non-armored coaxial cable line. For applications where cables run across sharp-edged structural paths, external flexible conduit or an armored variant should be utilized.

• Q: Can I connect a 1.0 metre probe directly to a 9.0 metre Proximitor sensor?

  A: No. A 1.0 metre probe requires a matching extension cable (e.g., 4.0 metres or 8.0 metres) to match the total system length calibration (typically 5.0 metres or 9.0 metres) of the Proximitor sensor. Mismatching total electrical lengths degrades measurement linearity and causes calibration errors.

Engineering & Installation Guide

• Mechanical Torque & Thread Installation: Always use a calibrated torque wrench when tightening the 3/8-24 mounting threads. Do not exceed a maximum mounting torque of 13.5 N-m (120 in-lb) to prevent shearing the outer case body or distorting the internal coil. Verify that the target area on the observed shaft is free of scratches, tool marks, and electrical runout to prevent noise interference.

• Electrical Connector Isolation: The miniature male coaxial connector is highly sensitive to moisture and particulate contamination. Ensure the connector is completely dry before mating. It is highly recommended to apply self-fusing silicone tape or install a connector protector kit over the mated coaxial junction to prevent grounding loops and signal degradation caused by exposure to oil or humidity.