330191-00-08-15-CN Bently Nevada 8 mm ETR Proximity Probe

Product Overview of the 330191-00-08-15-CN

The Bently Nevada 330191-00-08-15-CN is a 3300 XL 8 mm ETR proximity probe engineered for precise, non-contact displacement and vibration measurement in rotating machinery. As part of the 3300 XL series, this probe delivers engineering-grade accuracy for critical turbomachinery applications. The model features a 3/8-24 UNF thread and is supplied without armor. Its 1.5 meter total length suits installations where a compact probe reach is required. The probe operates with a -17.5 Vdc to -26 Vdc supply when installed with a nonincendive circuit per installation drawing 140979, drawing a maximum of 12 mA. For barrier installations, the supply range is -23 Vdc to -26 Vdc. Notably, operation at a more positive voltage than -23.5 Vdc can reduce the linear range, so precise voltage regulation is essential.

Key Specifications and Performance

The 330191-00-08-15-CN offers a nominal probe DC resistance of 7.73 Ω ± 0.50 from center conductor to outer conductor. Its output resistance is 50 Ω, and supply sensitivity is less than 2 mV change in output voltage per volt change in input voltage. The probe tip is molded from polyphenylene sulfide (PPS), while the case is constructed from AISI 303 or 304 stainless steel. The standard cable is a 75 Ω triaxial, FEP-insulated probe cable. Maximum rated tensile strength is 330 N (75 lbf) from probe case to probe lead and 270 N (60 lbf) at the probe lead to extension cable connectors. The connector material is gold-plated brass or gold-plated beryllium copper, with a maximum connector torque of 0.565 N·m (5 in·lbf). The probe case thread is 3/8-24 UNF, and the maximum length of thread engagement is 0.563 in. The probe mass is 323 g/m (11.4 oz).

Comparison with Similar Proximity Probes

• 3300 XL 8 mm (this model): 8 mm tip diameter, thicker PPS encapsulation, robust stainless steel case, 3/8-24 UNF thread.
• 3300 XL 5 mm: Smaller tip diameter, often used where space is limited but less resistant to physical abuse.
• 3300 XL 11 mm: Larger tip for extended linear range, but larger physical size may require more mounting space.

The 8 mm probe is recommended when possible for optimal robustness against physical abuse, thanks to its thicker encapsulation and larger body diameter.

Applications and Integration

This probe is designed for use with Bently Nevada extension cables and Proximitor sensors to meet entity parameters. Typical applications include steam turbines, compressors, and pumps where precise radial and axial position measurement is critical. The 3300 XL 8 mm ETR probe is suitable for high-temperature environments; the probe-only ambient temperature range for EPL Ga and Gc is -55°C to +232°C for T1 classification. For EPL Dc, the temperature schedule varies by classification. The probe seals differential pressure between tip and case using a Viton O-ring. However, probes are not pressure tested prior to shipment. When integrating into a machinery protection system, ensure that extension cables and Proximitor sensors are matched to maintain accuracy.

Installation and Maintenance

Install the probe using the 3/8-24 UNF thread, ensuring thread engagement does not exceed 0.563 in. The minimum unthreaded length is 0.0 in., and the minimum case length is 0.8 in. For nonincendive installations, follow installation drawing 140979. Verify supply voltage is within -17.5 Vdc to -26 Vdc for nonincendive circuits or -23 Vdc to -26 Vdc with barriers. Periodically inspect the probe tip and cable for physical damage, and check connector torque to 0.565 N·m (5 in·lbf). Avoid operation at voltages more positive than -23.5 Vdc to prevent reduced linear range. The probe's patented TipLoc and CableLoc designs provide robust bonds and high pull strength, enhancing reliability in demanding environments.