21504-02-12-05-02 | Bently Nevada 8 mm Probe Proximity Vibration Transducer

What Is the 21504-02-12-05-02?

When machinery vibration threatens uptime, the 21504-02-12-05-02 from Bently Nevada provides accurate proximity measurement. This 8 mm probe is part of the 7200 Proximity Transducer Systems family. It is engineered for continuous monitoring of shaft vibration and position. The transducer system includes a probe, extension cable, and proximitor. It operates with a power supply of -17.5 Vdc to -26 Vdc at 12 mA maximum consumption. The unit delivers a calibrated range of 80 mils (2.0 mm) starting at approximately 10 mils (0.25 mm) from the probe face.

Key Features & Technical Specs

• 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 as a system.
• Frequency Response: 0 to 10 kHz (0 to 600,000 cpm) with -5% at 10 kHz.
• Operating Temperature (Probe): -30°F to +350°F (-34°C to +177°C).
• Relative Humidity: Up to 95% noncondensing.
• System Weight: 1.3 lbs (0.59 kg).
• Total Length: 0.5 meter (20 inches) with tolerance +0.13 m, -0.05 m.
• Connector: Miniature male coaxial connector.

A distinctive feature is the 200 mV/mil scale factor. This provides high sensitivity for detecting small shaft movements. It helps operators catch early signs of bearing wear or imbalance.

Comparison with Similar Probes

Compared to standard 5 mm proximity probes, the 21504-02-12-05-02 8 mm diameter offers a larger sensing face. This improves linearity over the calibrated range. Many 8 mm probes have a scale factor around 200 mV/mil, but the Bently Nevada unit maintains ±4% accuracy as a system. Including interchangeability errors, the accuracy stays within ±9.5%. This makes it suitable for critical machinery where precision matters.

Applications & Use Cases

In turbomachinery applications, the 21504-02-12-05-02 monitors radial vibration and axial position. It is commonly used in steam turbines, compressors, and pumps. The probe resists direct contact with air, water, lube oil, and several chemicals. This corrosion resistance ensures reliable operation in harsh environments. For example, in a refinery, the probe can withstand exposure to sulfuric acid (10%) or MEK without performance loss.

Installation Guide

Mount the probe with 3/8-24 threads into a standard mounting hole. Ensure the unthreaded length of 20 mm is clear for proper positioning. The total length of 0.5 meter (20 inches) includes the probe and cable. Connect the miniature male coaxial connector to the extension cable. Verify the gap between probe face and target is within the calibrated range. For best results, follow Bently Nevada installation guidelines for gap voltage setting.

Maintenance & Reliability

Regular inspection of the probe and cable helps maintain accuracy. Check for physical damage or corrosion, especially in humid or chemical environments. The system operates reliably from -30°F to +350°F for the probe. Temperature sensitivity is typically -3% change in scale factor at +150°F (65°C) at 50 mils gap. This predictable behavior allows compensation in monitoring software. Periodic calibration verification ensures the scale factor stays within ±4%.

FAQs about 21504-02-12-05-02

Q: What is the calibrated range of the 21504-02-12-05-02?

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

Q: What is the scale factor and accuracy?

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

Q: What power supply is required?

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

Q: What is the frequency response?

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

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).

Product Support & Availability

The 21504-02-12-05-02 is available as new and original in factory packing. Petro Auto Tech stocks this Bently Nevada probe for fast delivery. Please verify current lifecycle status and availability with Petro Auto Tech before ordering.