The 21504-08-20-10-02 from Bently Nevada belongs to the reliable 7200 Proximity Transducer Systems family. This 8 mm probe features an 80 mm unthreaded length and a shorter 2.0 inch overall case length. These dimensions make it ideal for medium-depth mounting applications where standard probes cannot reach but extreme length is unnecessary.
Many industrial fans, blowers, and medium-sized compressors use this configuration. The total cable length is 1.0 metre with a miniature male coaxial connector. Therefore, this model offers a balanced solution between the 0 mm and 200 mm unthreaded versions.
The 21504-08-20-10-02 delivers a calibrated range of 80 mils (2.0 mm). Measurement begins at approximately 10 mils (0.25 mm) from the probe face. The scale factor is 200 mV/mil (7.87 V/mm) with ±4% accuracy when calibrated as a system. Including interchangeability errors, the tolerance stays within ±9.5%.
Linearity performance remains excellent. Within a 200 mV/mil straight line, deviation stays below 0.8 mils (0.02 mm) for system calibration. With interchangeability errors included, it remains within 2.3 mils (0.06 mm).
Frequency response covers 0 to 10 kHz (0 to 600,000 cpm). At 10 kHz, the response drops by only 5%. Consequently, this probe captures fast vibration events without meaningful signal loss.
Temperature sensitivity shows a typical -3% change in scale factor at +150°F (+65°C) with a 50 mil gap (1.27 mm). This stability ensures reliable readings across varying thermal environments.
Input power requires -17.5 Vdc to -26 Vdc at 12 mA maximum consumption. The output remains linear across the entire calibrated range. For best results, pair this probe with a Bently Nevada proximitor calibrated for the same 200 mV/mil scale factor.
Operating temperature for the proximitor ranges from -60°F to +212°F (-51°C to +100°C). The probe and extension cable handle -30°F to +350°F (-34°C to +177°C). Relative humidity can reach 95% non-condensing.
Corrosion resistance applies specifically to 8 mm probes like this one. Direct contact with air, water, lube oil, ammonium hydroxide, 10% sulfuric acid, MEK, or DMF will not affect probe operation. This makes the 21504-08-20-10-02 suitable for chemical processing environments.
The unthreaded length option is 80 mm. Overall case length option is 2.0 inches. Total length option is 1.0 metre (39 inches) with a tolerance of +0.25 metre, -0.10 metre (+10 inches, -4 inches).
Tip construction follows part number 21504- with 8 mm diameter. Case type is standard. Configuration threads are 3/8-24. Lead armor is not included.
Follow these steps to install the 21504-08-20-10-02 correctly. First, measure your mounting hole depth to confirm it accommodates the 80 mm unthreaded section. Next, clean the target shaft surface and remove any debris or old adhesive.
Then, thread the probe into the mounting hole using the 3/8-24 threads. Do not overtighten beyond finger-tight plus one half turn. Connect the miniature male coaxial connector to your extension cable. For reliable signals, use Bently Nevada approved cables only.
Maintain the recommended air gap of approximately 10 mils for the zero position. Finally, verify that power supply voltage stays between -17.5 Vdc and -26 Vdc.
Meanwhile, avoid sharp bends in the probe cable. Keep the cable away from surfaces exceeding 350°F. Additionally, use a matching proximitor that expects the 200 mV/mil scale factor.
1 x Bently Nevada 21504-08-20-10-02 probe
1 x Miniature male coaxial connector (pre-installed)
Factory packing box
Note: No certificates or warranty documents are included in the package.
We ship via FedEx, UPS, or DHL. Tracking numbers are provided after dispatch.
1. What makes the 21504-08-20-10-02 different from the 21504-00-28-10-02?
The main differences are the unthreaded length and case length. The 21504-08-20-10-02 has an 80 mm unthreaded section and a 2.0 inch case. The other version has 0 mm unthreaded and a 2.8 inch case. Choose based on your mounting depth needs.
2. Can I use this probe with a 5 metre extension cable?
Yes, you can add extension cables. However, total system length affects calibration accuracy. Bently Nevada recommends keeping the total length within approved limits for precise 200 mV/mil output.
3. Is the 2.0 inch case length shorter than standard?
Yes, the 2.0 inch case is shorter than the more common 2.8 inch or 3.2 inch options. This makes the 21504-08-20-10-02 suitable for machines with limited clearance around the mounting area.
4. How do I test this probe before installation?
Use a Bently Nevada proximity tester or an oscilloscope with a calibrated power supply. Measure the output voltage at known gap distances. Compare readings against the 200 mV/mil scale factor. A deviation beyond ±9.5% may indicate a problem.
5. What is the warranty on the 21504-08-20-10-02?
The manufacturer provides a 12-month factory warranty covering defects in materials and workmanship. The packaging list above does not include warranty papers. Please contact our sales team for warranty registration or claims.
| Brand Name | Bently Nevada |
| Model No. | 21504-08-20-10-02 |
| Product Type | Proximity Probe |
| hasMerchantReturnPolicy | Adjust according to reality |
| Shippingdetails | Adjust according to reality |
