When a Standard Probe Fails in a High-Pressure Steam Turbine
A petrochemical plant faced repeated signal dropouts on a steam turbine. The standard probe tip eroded under 34 Bar (500 psi) nitrogen pressure and high temperature. The solution: the Bently Nevada 146054-08-20-00-05, a 3300 ceramic capped proximity probe built for exactly this environment.
This probe combines an alumina ceramic (Al2O3) tip with an AISI 304 stainless steel case. It handles temperatures from -51°C to +177°C (-60°F to +351°F). The ceramic cap resists erosion and chemical attack, so the probe survives where standard plastic-tipped probes fail.
Technical Specifications That Matter
Linear Range and Accuracy
The probe delivers a 1.52 mm (60 mils) linear range from 0.25 to 1.78 mm (10 to 70 mils), roughly -4 to -16 Vdc. Its Incremental Scale Factor (ISF) is 7.87 V/mm (200 mV/mil) ±6.5% including interchangeability error, measured in 0.25 mm (10 mils) increments from 0°C to +45°C.
Mechanical Construction
The 3/8-24 UNF thread with a maximum thread engagement of 0.563 in ensures a secure mount. The probe measures 0.8 in case length and 2.0 meters (6.6 feet) total length. It uses a 75 Ω coaxial, FEP-insulated cable. Nominal DC resistance from center conductor to outer conductor is 7.88 ± 0.50 ohms.
Environmental Ratings
The probe seals against 34 Bar (500 psi) nitrogen. It carries CSA, ATEX, and IECEx approvals. For EPL Ga and Gc, the temperature classification spans T1 to T5, with T1 rated -55°C to +232°C and T5 rated -55°C to +40°C.
Where This Probe Performs
Steam turbine monitoring: The ceramic tip and 34 Bar pressure seal handle the high-temperature, high-pressure steam environment. The 2.0 m length fits standard turbine housings.
Compressor surge detection: The 1.52 mm linear range captures small shaft movements. The 7.87 V/mm sensitivity gives the control system clear, actionable data.
Replacement and upgrade: If you are replacing an older 3300 probe, this model offers the same 3/8-24 UNF thread and 75 Ω cable. It drops into existing mounting hardware without modification. For plants running 3300 XL systems, this probe maintains system accuracy and interchangeability.
Installation and Integration Notes
Mount the probe using the 3/8-24 UNF thread. Ensure thread engagement does not exceed 0.563 in. The probe operates with a -24 Vdc power supply and a 10 kW load, calibrated to an AISI 4140 steel target. For systems using other target materials, recalibration is required.
This probe has no connector (option 0 0). You will need to route the 2.0 m cable to your Proximitor Sensor. When integrating into existing monitoring networks, confirm cable routing and any required connection modules with your supplier.
Maintenance and Reliability
Inspect the ceramic tip periodically for cracks or erosion. Check cable insulation for wear, especially near high-vibration areas. The FEP insulation resists chemicals and moisture. Keep the probe within its rated temperature range to avoid signal drift. For safety-related applications, follow the manufacturer’s safety manual and perform periodic functional tests.
Selection Checklist
Before ordering, verify:
- Thread type: 3/8-24 UNF
- Total length: 2.0 meters (6.6 feet)
- Agency approval: CSA, ATEX, IECEx
- Target material: AISI 4140 steel (or recalibrate)
- Power supply: -24 Vdc
Oil AutoTech supplies the 146054-08-20-00-05 as new and original in factory packing. We offer fast dispatch, worldwide, with hands-on technical selection help. Contact Oil AutoTech today for pricing and availability.
Please verify current lifecycle status and availability with Oil AutoTech before ordering.
