21505-24-40-10-02 | Bently Nevada 80 mils Proximity Probe

Introduction: The Evolution of Vibration Monitoring

For decades, industrial rotating machinery has demanded reliable, accurate vibration measurement to prevent catastrophic failures. The 21505-24-40-10-02 from Bently Nevada represents a mature step in that evolution—a proximity probe engineered to deliver consistent, repeatable data in harsh environments. As plants moved from periodic manual checks to continuous online monitoring, the need for rugged, high-precision sensors became critical. This probe answers that need with a calibrated range of 80 mils (2.0 mm), starting at approximately 10 mils (0.25 mm) from the probe face.

What Is the 21505-24-40-10-02?

The 21505-24-40-10-02 is a Bently Nevada 7200 series proximity transducer system component. It is a probe designed to measure shaft vibration and position in rotating machinery. The part number breaks down as follows: unthreaded length of 2.4 inches, overall case length of 4.0 inches, total length of 1.0 metre (39 inches) with a tolerance of +0.25 metre / -0.10 metre, and a miniature male coaxial connector option. The probe has an 8 mm diameter and standard case with 3/8-24 threads. It includes stainless steel lead armor for durability.

Key Features & Technical Specifications

• 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; within ±9.5% including interchangeability errors.
• Linearity: Within 0.8 mils (0.02 mm) of a 200 mV/mil straight line when calibrated as a system; within 2.3 mils (0.06 mm) including interchangeability errors.
• Frequency Response: 0 to 10 kHz (0 to 600,000 cpm); -5% at 10 kHz.
• Power: -17.5 Vdc to -26 Vdc at 12 mA maximum consumption.
• Operating Temperature: Proximitor: -60°F to +212°F (-51°C to +100°C); 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 distinctive spec is the frequency response up to 10 kHz, which covers the vibration range of most high-speed rotating equipment, making it suitable for turbines, compressors, and pumps.

Real-World Applications

The 21505-24-40-10-02 is commonly used in machinery protection systems for critical rotating assets. For example, in a steam turbine train, this probe can monitor shaft vibration relative to the bearing housing, alerting operators to imbalance or misalignment. In addition, it is suitable for axial position monitoring, where precise gap measurement is essential. Because the probe is corrosion-resistant to air, water, lube oil, ammonium hydroxide, sulfuric acid (10%), MEK, and DMF, it performs reliably in demanding industrial environments.

Installation & Setup

Proper installation is key to accurate readings. Mount the probe using the 3/8-24 threaded case, ensuring the probe face is positioned at the recommended gap. The total length of 1.0 metre (39 inches) allows flexible routing to the Proximitor. Use the miniature male coaxial connector for a secure connection. Always follow the manufacturer's installation manual for torque and gap settings. Verify the system calibration after installation to achieve the specified scale factor.

Maintenance & Reliability

Routine inspection of the probe and cable is recommended to ensure long-term reliability. Check for physical damage to the lead armor and connector. Keep the probe face clean and free of debris. The probe's stainless steel armor protects against wear, and its corrosion resistance extends service life. Periodic verification of the system's scale factor and linearity helps maintain measurement accuracy over time.

Compatibility & Integration

The 21505-24-40-10-02 is part of the Bently Nevada 7200 proximity transducer system. It is designed to work with compatible Bently Nevada Proximitors and monitoring systems. For integration details, refer to the official Bently Nevada documentation or contact Petro Auto Tech for guidance.

Troubleshooting & Common Issues

If readings appear unstable, first check the probe gap and cable connections. A damaged connector or cable can cause intermittent signals. Verify that the power supply is within the specified range of -17.5 Vdc to -26 Vdc. If the scale factor deviates beyond tolerance, recalibrate the system. For persistent issues, consult the manufacturer's manual.

FAQ about 21505-24-40-10-02

Q: What is the calibrated range of the 21505-24-40-10-02?

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

Q: What power supply does this probe require?

A: It requires -17.5 Vdc to -26 Vdc at 12 mA maximum consumption.

Q: What is the frequency response of this probe?

A: The frequency response is 0 to 10 kHz (0 to 600,000 cpm), with -5% at 10 kHz.

Q: What is the total length of the probe cable?

A: The total length is 1.0 metre (39 inches), with a tolerance of +0.25 metre / -0.10 metre.

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).

Product Support & Availability

The 21505-24-40-10-02 is available from Petro Auto Tech in new, original factory packing. Contact Petro Auto Tech for current availability and ordering information. Please verify lifecycle status before ordering.