Bently Nevada 21504-12-28-10-02 8mm Proximity Probe

Bently Nevada 21504-12-28-10-02 Proximity Probe Overview

The Bently Nevada 21504-12-28-10-02 is a precision-engineered proximity probe vibration sensor designed for critical machinery protection. This model belongs to the reputable 7200 Proximity Transducer Systems family. It accurately measures shaft vibration, thrust position, and other dynamic movements in turbines, compressors, and pumps. Additionally, its rugged 8 mm tip construction and standard 3/8-24 threads simplify installation across various mounting brackets.

Specifically, this 21504-12-28-10-02 sensor delivers a calibrated range of 80 mils (2.0 mm), with measurement beginning at approximately 10 mils (0.25 mm) from the probe face. The scale factor is set at 200 mV/mil (7.87 V/mm), ensuring proportional and clear output signals for predictive maintenance systems. Moreover, the frequency response extends to 10 kHz (600,000 cpm), making it suitable for high-speed rotating equipment.

Key Technical Specifications

When evaluating output performance, the Bently Nevada 21504-12-28-10-02 demonstrates impressive linearity. When calibrated as a complete system, it stays within 0.8 mils (0.02 mm) of a 200 mV/mil straight line. Meanwhile, even when including interchangeability errors, it remains within 2.3 mils (0.06 mm) of that ideal line. This level of accuracy ensures dependable vibration data collection for condition monitoring programs.

The power requirements for this 21504-12-28-10-02 probe are straightforward and efficient. It accepts a DC supply voltage ranging from -17.5 Vdc to -26 Vdc, with a maximum current consumption of only 12 mA. Consequently, it integrates seamlessly with most existing Proximitor monitoring systems without requiring significant power upgrades.

Furthermore, the temperature sensitivity of this Bently Nevada 21504-12-28-10-02 is typically -3% change in scale factor at +150°F (+65°C) when measured at a 50 mils gap (1.27 mm). This predictable thermal performance makes it a reliable choice for environments with fluctuating operating temperatures.

Mechanical Configuration and Dimensions

The mechanical construction of the 21504-12-28-10-02 includes an unthreaded length of 120 mm (Option 12) and an overall case length of 2.8 inches (Option 28). The total length is 1.0 metre (39 inches), with a tolerance of +0.25 metre and -0.10 metre (+10 inches, -4 inches). Moreover, it comes with a miniature male coaxial connector (Option 02), which simplifies cable connections to extension cables or Proximitor sensors.

For installation, the tip features a standard 3/8-24 thread configuration, and the 8 mm diameter tip is built without lead armor. This design ensures straightforward mounting in standard probe holders and brackets commonly found in industrial machinery. The longer unthreaded length of 120 mm provides additional flexibility for deep-reach applications where standard probes may not fit properly.

Environmental and Corrosion Resistance

The operating temperature range for the Proximitor is from -60°F to +212°F (-51°C to +100°C). Meanwhile, the probe and extension cable can withstand temperatures from -30°F to +350°F (-34°C to +177°C). Therefore, this Bently Nevada 21504-12-28-10-02 performs reliably in both extreme cold and high-heat environments. The system also tolerates relative humidity up to 95%, non-condensing, without compromising measurement accuracy.

Additionally, corrosion resistance is a key feature for this 8 mm probe. Direct contact with air, water, lube oil, ammonium hydroxide, 10% sulfuric acid, MEK (methyl-ethyl ketone), or DMF (dimethylformamide) does not affect its operation. This chemical resilience makes the 21504-12-28-10-02 suitable for use in chemical plants, refineries, and other harsh industrial settings where fluid exposure is common.

Installation Best Practices

Proper installation of the Bently Nevada 21504-12-28-10-02 begins with ensuring the target surface is clean and smooth. For optimal performance, position the probe tip perpendicular to the shaft or target surface. First, mount the probe using the 3/8-24 threads into a suitable bracket or holder. Next, connect the miniature male coaxial connector to the extension cable or directly to the Proximitor sensor.

Additionally, you must verify the gap voltage during installation to confirm the probe is within its linear operating range. The calibrated range starts at approximately 10 mils (0.25 mm) from the probe face, so setting the initial gap between 30 and 50 mils is generally recommended for most applications. Finally, secure all connections and route cables away from high-voltage sources to prevent electrical interference.

Packaging and Shipping Information

Every 21504-12-28-10-02 unit ships in its original factory packaging to ensure maximum protection during transit. The package includes the proximity probe assembly with the miniature male coaxial connector pre-installed. Additionally, a mounting instruction sheet is provided for quick reference during installation.

For shipping, we exclusively use trusted global carriers such as FedEx, UPS, and DHL to guarantee fast and reliable delivery worldwide. Each order is dispatched within 24 hours of payment confirmation, and tracking information is provided promptly.

Frequently Asked Questions

1. What is the unthreaded length of the Bently Nevada 21504-12-28-10-02?
This 21504-12-28-10-02 features an unthreaded length of 120 mm (Option 12), which provides additional reach for deep-rear mounting applications compared to standard probes.

2. What is the calibrated range of this proximity probe?
The Bently Nevada 21504-12-28-10-02 offers a calibrated range of 80 mils (2.0 mm), with measurement beginning at approximately 10 mils (0.25 mm) from the probe face. This range is ideal for shaft vibration and position monitoring.

3. Can this 8 mm probe withstand chemical exposure?
Yes, probe operation is not affected by direct contact with air, water, lube oil, ammonium hydroxide, 10% sulfuric acid, MEK, or DMF. Therefore, it is suitable for chemically aggressive environments.

4. What power supply does the 21504-12-28-10-02 require?
The Bently Nevada 21504-12-28-10-02 requires a DC input voltage between -17.5 Vdc and -26 Vdc, with a maximum current draw of 12 mA. It is compatible with most standard Proximitor power supplies.

5. How does the longer unthreaded length benefit installation?
The 120 mm unthreaded length of the 21504-12-28-10-02 allows deeper probe placement in machinery where standard probes cannot reach the target surface, offering greater installation flexibility.