330851-06-000-070-10-00-CN Bently Nevada 1m FluidLoc Triax Probe

Product Overview

The 330851-06-000-070-10-00-CN is a heavy-duty 3300 XL 25 mm Proximity Probe precision-manufactured in the United States by Bently Nevada. Engineered as a high-reliability eddy current sensor, this device is designed to physically replace legacy 7200 25 mm, 7200 35 mm, and 25 mm Differential Expansion (DE) Integral transducer systems inside massive machinery housings. This configuration features a thick, metric M39×1.5 threaded body with a 70 mm overall case length and zero unthreaded length. Equipped with a 1.0-meter unarmored FluidLoc triaxial cable and bearing country-specific hazardous area approvals (CN), this industrial sensor provides precise sub-millisecond proximity tracking in severe steam turbine environments.

Core Technical Advantages

Premium FluidLoc Triaxial Barrier

The probe utilizes a 75-ohm triaxial cable insulated with rugged perfluoroalkoxyethylene (PFA). Engineered with Bently Nevada's proprietary FluidLoc internal blocking technology, this design prevents pressurized lubricating oils, aggressive chemical fluids, and superheated process steam from traveling along the cable core into clean instrumentation enclosures.

High-Performance PEEK Tip Molding

The 25 mm sensor head is molded from Polyetheretherketone (PEEK), a premium engineering thermoplastic. This material maintains exceptional structural tracking stability, high dielectric isolation, and strong resistance against mechanical erosion, fluid cavitation, and airborne chemical degradation inside industrial turbine housings.

Advanced Thermal & Mechanical Ruggedness

Housed in an AISI 304 stainless steel case, the probe operates continuously across a wide temperature spectrum from -35 °C to +200 °C, and survives intermittent peak exposures up to +250 °C for under 24 hours. Its large physical shell provides heavy structural rigidity, supporting a maximum rated torque configuration up to 163 N·m (120 ft·lb).

Technical Specifications

Installation and Maintenance

Mechanical Threading and Torque Rules

Manually thread the large M39×1.5 stainless steel probe body into the designated mounting bracket or casing portal. Ensure that the 0-inch unthreaded section matches your layout clearances perfectly. Set your operational depth gap, then tighten the locknuts using a calibrated torque wrench. While the rugged threads are rated for a maximum peak of 163 N·m (120 ft·lb), the manufacturer recommends a standard installation torque of 68 N·m (50 ft·lb) to prevent thread binding or mechanical stress on the internal coil housing.

Proximitor Sensor Calibration Calibration

Route the 1.0 m unarmored PFA triaxial lead back to a matching 3300 XL 25mm Proximitor Sensor unit. Power the proximity loop and monitor the raw DC output voltage with a digital multimeter. Carefully rotate the probe body to adjust the mechanical gap distance until the circuit reads the specified mid-range linear calibration voltage before locking down the assembly hardware.

Hazardous Location Safety Infrastructure

Ensure the field wiring satisfies the local classification rules specified by the CN suffix code. For intrinsically safe "ia" installations in Zone 0, connect the probe through an approved zener barrier or galvanic isolation block. For non-sparking "nA" or increased safety "ec" loops in Zone 2 / Division 2 areas, ensure all cable connections are clamped tightly to prevent accidental disconnection during operation.

Engineering Advantages

Seamless Retrofits for Obsolete Transducers

The flexible casing and thread selections of the 3300 XL 25mm series allow it to serve as a drop-in replacement for aging 7200 25mm, 7200 35mm, and older differential expansion transducers. This allows plant operators to upgrade obsolete protection systems without performing costly field modifications to turbine cases.

Certified Marine Infrastructure Capability

Tested under the ABS (American Bureau of Shipping) Steel Vessels Rules, this probe is certified for installation on offshore oil rigs, ship propulsion systems, and maritime processing plants. It handles heavy, continuous mechanical vibration and ambient salt-spray exposure with excellent structural stability.

Clear Temperature Code Tracking

The probe supports a detailed hazardous location temperature class matrix spanning categories T1 through T5. This structured rating index simplifies safety calculations for control engineers, ensuring compliance with environmental temperature thresholds from +40 °C up to +232 °C.

Technical FAQs

Q1: Why does this specific 25 mm proximity probe utilize a large M39×1.5 thread diameter?
A1: The extended linear measurement range of a 25 mm probe requires a larger internal induction coil assembly than smaller 8 mm models. The M39 body provides the necessary space to house this heavy coil assembly while offering excellent structural rigidity against high-pressure steam environments.

Q2: What is the risk of utilizing an unarmored cable versus an armored version?
A2: The unarmored cable version is much lighter, making it easier to pull through narrow internal conduit paths. However, because it lacks an outer stainless steel armor sleeve, it should not be exposed to open pathways where it could suffer physical damage from falling tools, heavy maintenance, or walking traffic.

Q3: How does the probe tip handle the short-term peak temperature limit of +250 °C?
A3: The PEEK tip material and PFA cable jackets can withstand high-temperature spikes up to +250 °C for up to 24 hours without melting or causing calibration drift. If a thermal spike exceeds this 24-hour limit, it can break down the fluid seals and cause permanent electrical shorting inside the sensor.