High-Precision Axial Position Transmitter for Reliable Machinery Monitoring
The Bently Nevada 991-25-70-01-CN 991 Thrust Sensor is a compact axial displacement monitoring transmitter designed to measure shaft thrust position in rotating machinery applications. As part of the trusted 991 Thrust Transmitter family, this device converts signals from a 3300 NSv proximity probe system into a standard 4–20 mA proportional output, providing direct communication with PLC, DCS, SCADA, and industrial control platforms.
Engineered for OEM equipment manufacturers and industrial operators, the 991-25-70-01-CN combines a 25–0–25 mil (approximately 2.5 mm) thrust measurement range, 7-meter transducer system, 35 mm DIN-rail mounting, and CN approval configuration. The integrated Proximitor® Sensor electronics simplify installation by eliminating the need for a separate signal conditioning module while maintaining accurate and stable axial position measurement.
Technical Specifications
| Parameter | Specification |
|---|
| Manufacturer | Bently Nevada |
| Model Number | 991-25-70-01-CN |
| Product Type | 991 Thrust Sensor / Thrust Transmitter |
| Measurement Function | Shaft axial displacement monitoring |
| Measurement Range | 25–0–25 mil (approximately ±0.635 mm electrical range, 2.5 mm system range) |
| Compatible Probe | Bently Nevada 3300 NSv Proximity Probe |
| Extension Cable System | Matching 3300 NSv extension cable |
| System Length | 7.0 m (23 ft) |
| Output Signal | 4–20 mA proportional current output |
| Power Supply | +12 to +35 VDC |
| Circuit Design | Two-wire loop powered |
| Mounting Style | 35 mm DIN-rail clip mounting |
| Electronics | Integrated Proximitor® Sensor |
| Diagnostic Output | PROX OUT and COM terminals |
| Operating Temperature | -35°C to +85°C |
| Storage Temperature | -51°C to +100°C |
| Humidity Rating | Up to 100% condensing, non-submerged |
| Dimensions | Approx. 82 × 35 × 75 mm |
| Weight | Approx. 0.43 kg |
Application Areas
The 991-25-70-01-CN is designed for machinery where continuous thrust position monitoring is required to improve reliability and prevent unexpected failures.
| Industry | Equipment Applications |
|---|
| Oil & Gas | Centrifugal compressors, process pumps |
| Petrochemical | Rotating process machinery |
| Power Generation | Turbine auxiliary equipment |
| Manufacturing | Motors, blowers, industrial fans |
| Water Treatment | Large rotating pumps |
| OEM Systems | Compressor packages and pump skids |
Typical uses include:
-
Shaft axial position measurement
-
Thrust bearing monitoring
-
Machinery protection systems
-
Condition monitoring applications
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Predictive maintenance programs
-
Control system feedback integration
Key Product Benefits
Integrated Proximitor® Sensor Technology
The 991 transmitter incorporates Proximitor® electronics inside the transmitter housing, providing signal conversion and conditioning in one compact package. This design reduces panel space requirements, minimizes wiring complexity, and improves system installation efficiency.
Extended 7-Meter Measurement System
The 70 configuration provides a 7-meter transducer system length, allowing flexible installation between the proximity probe location and the monitoring cabinet. This makes the transmitter suitable for larger machine layouts and OEM equipment designs.
DIN-Rail Mounting Convenience
The 01 mounting option provides a 35 mm DIN-rail clip design, allowing fast installation inside industrial control panels and automation cabinets. The compact mounting style is especially suitable for OEM machinery where available space is limited.
Standard 4–20 mA Output Integration
The transmitter outputs a standard industrial 4–20 mA signal proportional to shaft axial position, enabling easy connection with common industrial automation systems without additional converters.
Designed for OEM Rotating Equipment
The 991 Series is optimized for centrifugal air compressors, small pumps, motors, and fans where a simple and reliable thrust signal is required for machinery control systems.
Diagnostic Monitoring Capability
Additional diagnostic connections provide access to proximity-related signals, allowing technicians to verify sensor operation, installation condition, and measurement stability during maintenance activities.
Technical FAQs
1. What is the Bently Nevada 991-25-70-01-CN used for?
It is used to monitor shaft axial displacement and thrust position in rotating machinery, providing a proportional 4–20 mA signal to control systems.
2. What does the “25” designation mean?
The 25 option represents the 25–0–25 mil thrust measurement range, commonly used for axial position monitoring applications.
3. What does the “70” code indicate?
The 70 designation identifies the 7-meter (23 ft) transducer system length.
4. What does the “01” mounting option represent?
The 01 option specifies 35 mm DIN-rail clip mounting for installation inside electrical cabinets and machinery control panels.
5. What does the “CN” suffix indicate?
The CN suffix represents a country-specific approval/configuration option. The exact certification depends on the supplied configuration and application requirements.
6. Which probe system works with this transmitter?
The transmitter is designed for use with the Bently Nevada 3300 NSv proximity probe and matching extension cable system.
7. Does the 991-25-70-01-CN require an external Proximitor module?
No. The transmitter includes an integrated Proximitor® Sensor, eliminating the requirement for a separate external Proximitor unit.
8. What power supply does the transmitter require?
The unit operates from a +12 to +35 VDC loop-powered supply connected at the transmitter terminals.
9. What output signal does the transmitter provide?
It provides a standard 4–20 mA proportional output representing shaft axial displacement.
10. What machines commonly use the 991 series?
The 991 series is commonly installed on centrifugal compressors, small pumps, motors, fans, and OEM rotating equipment requiring thrust position monitoring.
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