330171-00-20-05-02-CN Bently Nevada 3300 5 mm Proximity Probe (1/4-28 UNF)

Product Overview

The 330171-00-20-05-02-CN  is a precision-engineered 3300 5 mm Proximity Probe featuring a 1/4-28 UNF thread, specifically designed by Bently Nevada for high-accuracy displacement monitoring. This non-armored transducer is optimized for tight mechanical clearances where a standard 8 mm probe is too large to interface with the machine casing. It is extensively utilized in critical rotating machinery—such as high-speed compressors, small steam turbines, and pumps—to monitor radial vibration and axial position. By providing reliable data to the Machinery Protection System (MPS), the 330171-00-20-05-02-CN plays a fundamental role in detecting rotor imbalances and bearing degradation, ensuring operational safety and preventing costly unplanned outages.

Suffix Breakdown

This specific configuration of the 3300 5 mm probe is defined by the following technical parameters:

• 330171: Base model for the 3300 5 mm Proximity Probe with 1/4-28 UNF mounting threads.

• 00: Unthreaded Length. Indicates that the probe body has 0.0 inches of unthreaded section; the entire case is threaded.

• 20: Overall Case Length. The total length of the probe housing is 2.0 inches.

• 05: Total Length. The integrated probe cable length is 0.5 meter (1.6 feet).

• 02: Connector Option. Equipped with a miniature coaxial ClickLoc connector for secure, low-loss signal transmission.

• CN: Agency Approval. Specifically certified for the Chinese market, meeting regional hazardous area and safety standards.

Technical Specifications

Technical FAQs

How do I identify the 1/4-28 UNF thread version versus the 3/8-24 version?

The 330171 base model number specifically denotes the 1/4-28 UNF thread series. The smaller diameter of the 1/4-inch thread is visually distinct and is intended for machines with smaller tapped ports.

What are the consequences of using a non-armored cable in an industrial setting?

Non-armored probes like the 330171-00-20-05-02-CN are easier to route through tight conduits but lack the mechanical protection against crushing or abrasion. It is recommended to install these within protective conduit or internal machine housings to prevent cable damage.

Is the "CN" version compatible with international Proximitor sensors?

Yes, the electrical characteristics of the "CN" approved probe are identical to the standard version. It remains fully compatible with 3300 XL and standard 3300 Proximitor sensors, provided the total system length is matched.

Engineering & Installation Guide

Mounting Torque and Thread Integrity

Due to the smaller 1/4-28 UNF thread size, installers must exercise caution not to exceed the maximum torque limit (typically 3.4 N-m or 30 in-lb). Over-torquing can strip the threads or damage the internal transducer coil. Always use a thread lubricant that is compatible with the operating environment to prevent galling during future removal.

Precision Gapping for 5 mm Systems

The 5 mm probe has a narrower linear range (approx. 50 mils) compared to 8 mm systems. For a standard -24 VDC system, the target gap voltage should typically be set at -6.0 VDC to ensure the probe operates within the most linear portion of its curve. Verify the "Field Notification Letter" for any specific "CN" calibration offsets if applicable.