21504-00-40-50-02 | Bently Nevada 8 mm Proximity Probe Transducer

Introduction to the Bently Nevada 21504-00-40-50-02 Proximity Probe

When unplanned downtime threatens your rotating machinery, the 21504-00-40-50-02 from Bently Nevada provides the reliable vibration data you need. This 8 mm proximity probe is part of the 7200 Proximity Transducer Systems family, engineered for continuous monitoring in harsh industrial environments. With a calibrated range of 80 mils (2.0 mm) starting at approximately 10 mils (0.25 mm) from the probe face, it delivers precise shaft displacement measurements.

Key Features and Technical Specifications

• Scale Factor: 200 mV/mil (7.87 V/mm) with ±4% accuracy when calibrated as a system.
• Linearity: Within 0.8 mils (0.02 mm) of a 200 mV/mil straight line as a system; within 2.3 mils (0.06 mm) including interchangeability errors.
• Frequency Response: 0 to 10 kHz (0 to 600,000 cpm) with -5% at 10 kHz (600,000 cpm).
• Input 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: To 95%, noncondensing.
• System Weight: 1.3 lbs (0.59 kg).

One distinctive spec is the temperature sensitivity: typically -3% change in scale factor at +150°F (+65°C) at a 50 mils gap (1.27 mm). This means the probe maintains accuracy even under thermal stress, reducing false alarms.

Real-World Applications

In petrochemical plants, the 21504-00-40-50-02 monitors compressor shaft vibration to prevent catastrophic failures. For power generation turbines, its 0 to 10 kHz frequency response captures both slow-speed and high-speed events. Additionally, the probe's corrosion resistance to air, water, lube oil, ammonium hydroxide, and sulfuric acid (10%) makes it ideal for harsh chemical environments.

Installation and Setup Guidance

Mount the 8 mm probe using the 3/8-24 thread into a standard mounting hole. Ensure the unthreaded length is 00 mm and the overall case length is 4.0 inches as specified. The total cable length is 0.5 metre (20 inches) with a tolerance of +0.13 metre, -0.05 metre (+5 inches, -2 inches). Connect the miniature male coaxial connector to the Proximitor. Verify the gap setting within the calibrated range for optimal linearity.

Routine Maintenance and Reliability

Inspect the probe and cable periodically for physical damage or contamination. The probe's rugged design withstands temperatures up to +350°F (-34°C to +177°C) and humidity up to 95% noncondensing. Regular calibration checks ensure the scale factor remains within ±4% as a system. For long-term reliability, follow Bently Nevada's recommended maintenance intervals.

Compatibility and Integration

The 21504-00-40-50-02 integrates with Bently Nevada 7200 series Proximitors and monitoring systems. Its 200 mV/mil output is compatible with standard vibration monitoring modules. For system-level calibration, pair it with the specified Proximitor to achieve ±4% accuracy. Refer to the official Bently Nevada documentation for detailed integration guidelines.

Frequently Asked Questions

Q: What is the calibrated range of the 21504-00-40-50-02?

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 and its accuracy?

A: The scale factor is 200 mV/mil (7.87 V/mm) with ±4% accuracy when calibrated as a system, and within ±9.5% including interchangeability errors.

Q: What is the operating temperature range for the probe?

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

Q: What is the input power requirement?

A: The input power is -17.5 Vdc to -26 Vdc at 12 mA maximum consumption.

Q: Is the probe resistant to corrosive environments?

A: Yes, for 8 mm probes, operation is not affected by direct contact with air, water, lube oil, ammonium hydroxide, sulfuric acid (10%), MEK, or DMF.

Product Support and Availability

The Bently Nevada 21504-00-40-50-02 is available in new and original factory packing with a 12-month warranty. Contact Petro Auto Tech to verify current lifecycle status and availability before ordering. In stock and ready to ship for critical applications.