21504-24-44-05-02 | Bently Nevada 8 mm Probe Proximity Vibration

Introduction to the 21504-24-44-05-02

When machinery vibration threatens uptime, the 21504-24-44-05-02 from Bently Nevada provides the reliable measurement you need. This 8 mm proximity probe is part of the 7200 series, engineered for continuous monitoring of rotating equipment. With a calibrated range of 80 mils (2.0 mm) and a scale factor of 200 mV/mil, it delivers accurate displacement data for predictive maintenance programs.

This new, original factory-packed unit includes a 12-month warranty, ensuring you receive a genuine component ready for installation. Whether you are upgrading an existing system or building a new monitoring setup, the 21504-24-44-05-02 offers the performance and durability expected from Bently Nevada.

Key Features and Technical Specifications

The 21504-24-44-05-02 is designed for precision and reliability. Its key specifications include:

• Power: -17.5 Vdc to -26 Vdc at 12 mA maximum consumption.
• Calibrated Range: 80 mils (2.0 mm), beginning at approximately 10 mils (0.25 mm) from the probe face.
• Scale Factor: 200 mV/mil (7.87 V/mm), ±4% when calibrated as a system.
• Linearity: Within 0.8 mils (0.02 mm) of a 200 mV/mil straight line when calibrated as a system.
• Frequency Response: 0 to 10 kHz (0 to 600,000 cpm); -5% at 10 kHz.
• Temperature Sensitivity: Typically -3% change in scale factor at +150°F (+65°C) at 50 mils gap (1.27 mm).
• Operating Temperature (Proximitor): -60°F to +212°F (-51°C to +100°C).
• Operating Temperature (Probe and Extension Cable): -30°F to +350°F (-34°C to +177°C).
• Relative Humidity: Up to 95%, noncondensing.
• System Weight: 1.3 lbs (0.59 kg).

One standout feature is the total length option of 0.5 metre (20 inches) with a tolerance of +0.13 metre / -0.05 metre, ensuring proper installation clearance. Additionally, the probe tip diameter is 8 mm, with a standard case configuration and 3/8-24 threads for secure mounting.

Applications and Use Cases

The 21504-24-44-05-02 is ideal for monitoring shaft vibration and position in turbines, compressors, pumps, and other rotating machinery. Its non-contact measurement principle makes it suitable for high-speed applications where physical contact would be impractical. For example, in a steam turbine train, this probe can detect early signs of shaft misalignment or bearing wear, allowing maintenance teams to intervene before costly failures occur. Furthermore, its wide frequency response captures both low-speed and high-speed dynamics, making it versatile across different machine types.

Installation Guide

Proper installation is critical for accurate readings. Begin by verifying the probe's total length (0.5 metre) fits your mounting location. The 8 mm diameter probe uses 3/8-24 threads, so ensure the mounting hole matches this specification. When positioning the probe, maintain the recommended gap of approximately 10 mils (0.25 mm) from the target surface to start the calibrated range. Use the provided miniature male coaxial connector for signal output, and route the cable away from high-voltage sources to avoid interference. Always follow the manufacturer's installation manual for detailed steps.

Maintenance and Reliability

Regular inspection of the probe and cable is essential for long-term reliability. Check for physical damage, such as cuts or kinks in the cable, and ensure the probe tip remains clean and free of debris. The probe is corrosion-resistant to air, water, lube oil, ammonium hydroxide, sulfuric acid (10%), MEK, and DMF, making it suitable for harsh environments. However, avoid exposing the probe to temperatures outside its rated range, as this could affect performance. By incorporating these checks into your routine, you minimize downtime and extend the life of your monitoring system.

Compatibility and Integration

The 21504-24-44-05-02 is designed to work with Bently Nevada 7200 series monitoring systems. It provides a standard 200 mV/mil output that can be connected to compatible monitors, such as the 3300 or 3500 series, for real-time data acquisition. The miniature coaxial connector ensures a secure connection, and the probe's frequency response of 0 to 10 kHz makes it compatible with most industrial vibration monitoring applications. For integration with existing systems, verify that the power supply meets the -17.5 Vdc to -26 Vdc requirement.

Troubleshooting and Common Issues

If you encounter erratic readings, first check the power supply voltage and ensure it is within the specified range. Next, inspect the probe tip for contamination or damage, as this can affect the scale factor. If the output is lower than expected, verify the air gap is within the calibrated range. For persistent issues, consult the Bently Nevada documentation or contact Petro Auto Tech for technical support.

Frequently Asked Questions

Q: What is the calibrated range of the 21504-24-44-05-02?

A: The calibrated range is 80 mils (2.0 mm), beginning at approximately 10 mils (0.25 mm) from the probe face.

Q: What is the scale factor of this probe?

A: The scale factor is 200 mV/mil (7.87 V/mm), with a tolerance of ±4% when calibrated as a system.

Q: What is the operating temperature range for the probe and extension cable?

A: The probe and extension cable operate from -30°F to +350°F (-34°C to +177°C).

Q: Does the 21504-24-44-05-02 come with a warranty?

A: Yes, it includes a 12-month factory warranty.

Product Support and Availability

The 21504-24-44-05-02 is available from Petro Auto Tech, an industrial automation parts supplier. We maintain this item in stock and ready to ship. For ordering or technical inquiries, contact Petro Auto Tech to ensure you receive genuine Bently Nevada parts with full support.