The 21504-20-32-10-02 from Bently Nevada is a specialized member of the 7200 Proximity Transducer Systems family. This 8 mm probe features an extended 200 mm unthreaded length. Why does this matter? It allows the sensor to reach deeper mounting locations where standard probes cannot fit.
Many large compressors and turbines have thick casings or recessed mounting holes. For these situations, the 21504-20-32-10-02 provides the necessary reach. The overall case length is 3.2 inches, and the total cable length is 1.0 metre with a miniature male coaxial connector.
The 21504-20-32-10-02 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 remains a key strength. 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%. Therefore, this probe captures high-speed vibration events reliably.
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 consistent readings even when machine temperatures fluctuate.
Input power requires -17.5 Vdc to -26 Vdc at 12 mA maximum consumption. The output remains linear across the entire calibrated range. For optimal performance, pair this probe with a Bently Nevada proximitor calibrated to 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 21504-20-32-10-02 suitable for chemical plants and refineries.
The unthreaded length option is 200 mm. Overall case length option is 3.2 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 21504-20-32-10-02 correctly. First, verify that your mounting hole depth accommodates the full 200 mm unthreaded section. Next, clean the target shaft surface thoroughly. Then, carefully insert the probe into the hole without forcing it.
Thread the probe using the 3/8-24 threads until finger-tight. Add no more than one half turn beyond that. Connect the miniature male coaxial connector to your extension cable. Use only Bently Nevada approved cables for signal integrity.
Maintain the recommended air gap of approximately 10 mils for the zero position. Finally, confirm 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 21504-20-32-10-02 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 information is provided after shipment.
1. When should I choose the 21504-20-32-10-02 over other versions?
Choose this version when your mounting hole has a long unthreaded section before the threads begin. The 200 mm unthreaded length fits deep recesses. For shallow mounts, select the 00 (0 mm) or 16 (16 mm) unthreaded options instead.
2. Can I cut the unthreaded section to make it shorter?
No, cutting the probe will damage it. The internal coil and tip construction are precisely calibrated. If you need a shorter unthreaded length, order a different configuration like 21504-16-32-10-02 or 21504-00-28-10-02.
3. Is this probe compatible with older Bently Nevada monitors?
Yes, it works with most Bently Nevada proximitors and monitoring systems that expect an 8 mm probe with 200 mV/mil output. However, always verify your monitor's input specifications before purchasing.
4. How does the 200 mm unthreaded length affect performance?
The extended length does not change electrical performance. The same calibrated range, scale factor, and frequency response apply. Only the mechanical dimensions differ.
5. What is the warranty on the 21504-20-32-10-02?
The manufacturer provides a 12-month factory warranty covering defects in materials and workmanship. The packaging list above does not include warranty documents. Contact our team
| Brand Name | Bently Nevada |
| Model No. | 21504-20-32-10-02 |
| Product Type | Proximity Probe |
| hasMerchantReturnPolicy | Adjust according to reality |
| Shippingdetails | Adjust according to reality |
