The Bently Nevada 991-25-70-01-01 is a 2-wire, loop-powered thrust transmitter that converts signals from a 3300 NSv proximity probe into a 4-20 mA output proportional to axial shaft position. Designed for general-purpose machinery like centrifugal air compressors, pumps, and fans, it eliminates the need for external signal conditioning and provides reliable thrust monitoring in tight installation spaces.
Item No :
991-25-70-01-01Order(MOQ) :
1 PiecePayment :
EXWProduct Origin :
USAShipping Port :
WuhanLead Time :
3~5 daysWeight :
3kg| Feature | Description |
|---|---|
| Manufacturer | Bently Nevada (Baker Hughes) |
| Product Family | 991 Series Thrust Transmitter |
| Model / Order Code | 991-25-70-01-01 |
| Core Function | Converts axial displacement (thrust) to a 4-20 mA signal |
| Full-scale Range | ±25 mils (0.6 mm total) |
| Output Signal | 4-20 mA DC, loop-powered (2-wire) |
| Compatibility | 3300 NSv proximity probe and extension cable |
| System Length | 7.0 meters (23.0 feet) |
| Mounting Option | 35 mm DIN-rail clips |
| Power Supply | 12 to 35 Vdc at transmitter terminal |
| Agency Approval | CSA Division 2 |
| Operating Temp. | -35°C to +85°C |
| Construction | Potted for operation in 100% condensing humidity |
| Diagnostics | Non-isolated PROX OUT and COM terminals for gap verification; Not OK/Signal Defeat circuit |
| Weight | Approx. 0.43 kg |
| Category | Model | Description |
|---|---|---|
| 5m System Length | 991-25-50-01-01 | Same transmitter, ±25 mils range, but with 5.0m system length |
| Metric Range | 991-06-50-01-01 | Same features with 0.6-0-0.6 mm full-scale range |
| Bulkhead Mounting | 991-25-70-02-01 | Same specs, but bulkhead mounting instead of DIN-rail |
| Proximity Probe | 3300 NSv Series | Required narrow side-view proximity probe for system compatibility |
| Extension Cable | 330930 Series | Matching extension cable (5m or 7m options) |
| Vibration Transmitter | 990 Series | Vibration version for general-purpose vibration monitoring (not thrust) |
Q1: What is the primary application of the 991-25-70-01-01?
It is used to continuously monitor axial shaft position (thrust) on general-purpose machinery such as centrifugal air compressors, pumps, motors, and fans, providing a 4-20 mA signal to the control system for protection alarming and logic .
Q2: What does the model number suffix "25-70-01-01" mean?
The suffix defines configuration: 25 = ±25 mils full-scale range; 70 = 7.0m system length (probe + extension cable); 01 = 35mm DIN-rail mounting; 01 = CSA Division 2 agency approval .
Q3: Does the 991 transmitter require an external proximity sensor or driver?
No. The 991 integrates the proximity sensor conditioning circuitry (Proximitor) internally. It accepts the 3300 NSv probe and extension cable directly, eliminating the need for a separate driver unit .
Q4: What are the diagnostic features of the 991 transmitter?
It includes non-isolated PROX OUT and COM terminals for verifying probe gap voltage during setup, and a "Not OK/Signal Defeat" circuit that prevents false high outputs from faulty probes or loose connections . It also has a test input pin for simulating probe movement to verify the 4-20 mA loop without physically moving the rotor .
Q5: Is the 991 transmitter suitable for critical machinery like large turbines?
No. The 991 is designed for non-critical, general-purpose machinery. For critical turbine or compressor protection, Bently Nevada recommends the 3500 series monitoring system.
The Bently Nevada 21000-16-10-00-120-03-02 is a Proximity Probe Housing Assembly from the 21000 series, designed for external mounting of 3300 XL 8 mm proximity probes on critical rotating machinery, enabling safe external probe access for gap adjustment or replacement without disassembling the machine.
The Bently Nevada 21000-28-05-00-085-03-02 is a Proximity Probe Housing Assembly from the 21000 series, designed for external mounting of 3300 XL 8 mm proximity probes. It provides mechanical protection, precise probe alignment, and hazardous area certification, enabling safe external probe access for gap adjustment or replacement without disassembling the machine.
The Bently Nevada 21000-16-10-00-120-03-02 is a Proximity Probe Housing Assembly from the 21000 series, designed for external mounting of 3300 XL 8 mm proximity probes on critical rotating machinery . It provides mechanical protection, precise probe alignment, and hazardous area certification, enabling safe external probe access for gap adjustment or replacement without disassembling the machine.
The Bently Nevada 330854-040-25-CN is a 4.0-meter armored extension cable from the 3300 XL 25 mm Proximity Transducer System. The 25 mm system provides the longest linear range in the 3300 XL family (up to 12.7 mm), making it ideal for applications requiring measurement of large axial movements.
The Bently Nevada 330930-060-01-05 is a 6.0-meter armored extension cable from the 3300 XL NSv Proximity Transducer System. It is specifically designed for the 3300 NSv system, which uses a narrower probe tip and side-view mounting for installations with limited radial clearance, such as centrifugal air compressors and small pumps.
The Bently Nevada 330730-080-01-00 is an 8.0-meter armored extension cable from the 3300 XL 11 mm Proximity Transducer System. This specific configuration features flexible AISI 302 stainless steel armor with an outer FEP jacket for mechanical protection against crushing, abrasion, and fluid ingress in high-exposure areas.
The Bently Nevada 330130-080-10-00 is an 8.0-meter armored extension cable from the 3300 XL 8 mm Proximity Transducer System. It serves as the critical signal link between a 3300 XL proximity probe and its Proximitor® sensor, transmitting high-frequency eddy-current signals for vibration, thrust position, and Keyphasor measurements on critical rotating machinery. The "-10" cable option also includes FluidLoc™ technology to prevent oil migration along the cable core in pressurized bearing applications.
The Bently Nevada 330130-080-00-00 is an 8.0-meter standard extension cable from the 3300 XL 8 mm Proximity Transducer System. This specific configuration is the standard (non-armored) cable without connector protector and without agency approvals, making it suitable for general-purpose industrial environments.
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