21505-00-28-10-02 | Bently Nevada 8 mm Probe Proximity Vibration Sensor

Introduction to the Bently Nevada 21505-00-28-10-02

When rotating machinery faces unexpected vibration, unplanned downtime can disrupt operations and inflate costs. The 21505-00-28-10-02 from Bently Nevada provides a dependable solution for continuous vibration monitoring. This proximity probe is engineered to detect shaft vibration and displacement with high accuracy, helping maintenance teams identify issues before they escalate.

As part of the 7200 proximity transducer system, the 21505-00-28-10-02 offers a calibrated range of 80 mils (2.0 mm), beginning at approximately 10 mils (0.25 mm) from the probe face. This capability makes it suitable for a wide range of turbomachinery and rotating equipment applications.

Key Features and Technical Specifications

• Part Number: 21505-00-28-10-02
• Model: Probe Proximity Vibration
• Manufacturer: Bently Nevada
• Probe Diameter: 8 mm
• Thread Configuration: 3/8-24
• Total Length: 1.0 metre (39 inches), tolerance +0.25 m / -0.10 m
• Connector: Miniature male coaxial connector
• Lead Armor: Stainless steel
• Power Input: -17.5 Vdc to -26 Vdc at 12 mA maximum consumption
• Calibrated Range: 80 mils (2.0 mm), starting at 10 mils (0.25 mm) from probe face
• Scale Factor: 200 mV/mil (7.87 V/mm), ±4% (system calibrated)
• Linearity: Within 0.8 mils (0.02 mm) of a 200 mV/mil straight line (system calibrated)
• Frequency Response: 0 to 10 kHz (0 to 600,000 cpm)
• Temperature Sensitivity: Typically -3% change in scale factor at +150°F (+65°C) at 50 mils gap
• 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 frequency response of 0 to 10 kHz, which covers a broad spectrum of vibration frequencies found in industrial rotating equipment. This allows the probe to capture both low-speed and high-speed machinery dynamics, providing valuable data for predictive maintenance.

Real-World Applications

In petrochemical plants, power generation facilities, and manufacturing lines, the 21505-00-28-10-02 excels at monitoring shaft vibration in pumps, compressors, turbines, and motors. Its robust design withstands harsh environments, including exposure to air, water, lube oil, ammonium hydroxide, sulfuric acid (10%), MEK, and DMF, as specified for 8 mm probes. This corrosion resistance ensures reliable performance even in demanding industrial settings.

Furthermore, the probe's ability to operate across a wide temperature range—from -60°F to +212°F for the proximitor and -30°F to +350°F for the probe and extension cable—makes it suitable for both cold climate and high-heat applications. Whether monitoring a critical compressor in an Arctic pipeline or a turbine in a tropical power plant, this sensor delivers consistent, accurate readings.

Installation and Setup

Proper installation is crucial for accurate vibration measurement. The 21505-00-28-10-02 features a 3/8-24 thread configuration, allowing secure mounting into standard probe mounting holes. The total length of 1.0 metre (39 inches) provides flexibility in positioning the probe relative to the target surface.

When installing, ensure the probe face is positioned within the calibrated range (10 to 90 mils from the shaft). Use the provided miniature male coaxial connector for a secure electrical connection. Always follow the manufacturer's guidelines for gap setting and cable routing to avoid signal interference.

Maintenance and Reliability

Routine inspection of the probe and its connections is recommended to maintain measurement accuracy. Check for any physical damage to the lead armor or connector, and verify that the probe face remains clean and free of debris. The stainless steel armor protects against mechanical wear, extending the sensor's service life.

Given the probe's corrosion resistance, it can withstand direct contact with many industrial fluids, reducing the need for frequent replacements. This durability translates into lower maintenance costs and reduced downtime, offering a strong return on investment for facilities that rely on continuous vibration monitoring.

Troubleshooting Common Issues

If the probe fails to provide a signal, first verify that the power supply is within the specified range (-17.5 Vdc to -26 Vdc at 12 mA). Check the coaxial connector for proper seating and inspect the cable for cuts or abrasions. If readings appear erratic, confirm that the probe gap is within the calibrated range and that the target surface is clean.

For persistent issues, consult the official Bently Nevada documentation or contact Petro Auto Tech for technical support. Our team can assist with troubleshooting and provide guidance on replacement if necessary.

Frequently Asked Questions

Q: What is the calibrated range of the 21505-00-28-10-02?

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

Q: What power supply is required for this proximity probe?

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

Q: What is the frequency response of the 21505-00-28-10-02?

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

Q: Can the probe operate in high-humidity environments?

A: Yes, it can operate in relative humidity up to 95%, noncondensing.

Product Support and Availability

The 21505-00-28-10-02 is available at Petro Auto Tech, an industrial automation parts supplier. Each unit is new and original in factory packing, backed by a 12-month factory warranty. Contact Petro Auto Tech for current availability and ordering information.