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Brand: Bently Nevada
Bently Nevada 140734-02 3500/42M Prox/Seismic Monitor Board
Description
Bently Nevada 140734-02 3500/42M Proximitor Seismic Monitor main board
The Bently Nevada 140734-02 is commonly listed as the main board of the 3500/42M Proximitor Seismic Monitor, a four-channel monitor in the 3500 rack that accepts proximity, velocity and acceleration transducers in the same module. That mix is what separates it from the 3500/40M: besides shaft vibration, position and expansion it can measure casing acceleration and velocity and shaft absolute vibration.
Seven Star LLC supplies the board in Oman and the GCC as a spare or expansion part. The official 3500/42M datasheet lists 176449-02 for the monitor in its spares table; compare your board label with that number and with 140734-02 before ordering.
140734-02 technical specifications
| Parameter | Specification |
|---|---|
| Manufacturer / part number | Bently Nevada 140734-02 (3500/42M Proximitor Seismic Monitor main board) |
| Channels | 4, programmed in pairs |
| Inputs | Proximity, velocity (Seismoprobe/Velomitor) or acceleration transducers |
| Functions | Radial vibration, thrust position, eccentricity, differential expansion, REBAM, acceleration, velocity, shaft absolute, circular acceptance region |
| Power consumption | 7.7 W typical |
| Radial vibration sensitivity | 3.94 mV/µm (100 mV/mil) or 7.87 mV/µm (200 mV/mil) |
| Acceleration sensitivity | 10 mV/(m/s²) (100 mV/g) |
| Velocity sensitivity | 20 mV/(mm/s) pk, 5.8 mV/(mm/s) pk or 4 mV/(mm/s) pk (500, 145 or 100 mV/(in/s) pk) |
| Recorder outputs | +4 to +20 mA per channel, 0 to 600 Ω load, 12 V compliance |
| Buffered outputs | Front coaxial connector per channel, 550 Ω, short-circuit protected |
| Operating temperature | -30°C to +65°C; 0°C to +65°C with internal-barrier I/O |
| Storage temperature | -40°C to +85°C |
| Main module size / weight | 241.3 x 24.4 x 241.8 mm / 0.91 kg (2.0 lb) |
| I/O module (non-barrier) | 241.3 x 24.4 x 99.1 mm, 0.20 kg (0.44 lb) |
Figures are from the 3500/42M datasheet (143694 Rev. AE).
Why choose a 3500/42M instead of a 3500/40M
Where a machine needs both shaft and casing data, one 3500/42M can cover a pair of proximity probes and a pair of seismic sensors, saving rack slots. Shaft absolute measurement combines a proximity probe and a velocity transducer on the same bearing housing to give the true shaft motion in space. Acceleration II, Velocity II and circular acceptance region functions need newer firmware and software, so they are not available on every installed base.
The 3500/40M remains the better fit for pure Proximitor applications, and the 3500/42M for mixed ones. Both take rear I/O modules, but the two I/O families are not interchangeable.
I/O modules used with the 3500/42M
| Part number | I/O description |
|---|---|
| 128229-01 | Prox/Seismic I/O, internal terminations (order option 01) |
| 128240-01 | Prox/Seismic I/O, external terminations (02) |
| 135489-01 | Internal barriers, 4 x Prox/Accel (04) |
| 135489-02 | Internal barriers, 2 x Prox/Accel and 2 x Velomitor (05) |
| 135489-03 | Internal barriers, 4 x Velomitor (06) |
| 138708-01 / 138700-01 | Shaft absolute I/O, internal / external terminations (07, 08) |
| 140471-01 / 140482-01 | Prox/Velom I/O, internal / external terminations (09, 10) |
External termination blocks cannot be used with internal-termination I/O modules.
Selection and ordering checklist for 140734-02
- List the transducers per channel: proximity probe, Velomitor, Seismoprobe, accelerometer or high-temperature velocity sensor.
- Select the I/O type; Seismoprobe and Velomitor remain supported on the 128229-01 board but the datasheet marks them as not recommended.
- Check the firmware revision and rack software required for shaft absolute, REBAM or acceleration II/velocity II.
- Decide on internal barriers if intrinsic safety is needed.
- State agency approval and the quantity of spare I/O connector headers (00580434, 00580432).
Installation, commissioning and maintenance
Install in a full-height front slot with the matching rear module. After a swap, confirm the OK LED and TX/RX LED, check bypass mode is off and compare the displayed 1X vector against a portable analyser. Seismic channels depend on correct sensor power and grounding, so check the signal common and cable shield terminations before blaming the monitor. Keep a backup of the rack configuration since a new board arrives without it.
Typical applications in Oman and the GCC
Mixed shaft and casing monitoring is common on gas turbines, steam turbines, large pumps and fans in power and desalination plants, and on compressor trains in gas processing. High ambient temperature and fine dust make sealed junction boxes and clean shield terminations important. Velomitor and accelerometer cabling should be kept apart from power cables because seismic signals are low level.
Related 3500/42M part numbers
| Part number | Item |
|---|---|
| 176449-02 | 3500/42M monitor (datasheet spares list) |
| 140734-02 | 3500/42M main board listing (this page) |
| 143489 | 3500/42M monitor user guide |
| 00530843 | Four-pin connector shunt for Prox/Seismic I/O |
| 00517018 | Eight-pin connector shunt for shaft absolute I/O |
Spares and firmware notes for 140734-02
Ask for the revision letter on the board and the firmware version before ordering the 140734-02 for a rack that uses shaft absolute, REBAM or acceleration II / velocity II functions: the datasheet lists minimum rack software and monitor firmware for each. Keep the 3500/42M user guide 143489 with the maintenance file, and hold spare connector headers and shunts for the I/O module because these small parts are what usually go missing during a repair.
Information to send with your RFQ
- Part number 140734-02 and quantity
- Board label photograph or revision and firmware number
- Transducer list for all four channels
- I/O module part number installed
- Delivery location in Oman or the GCC and condition required
Related Bently Nevada products: Bently Nevada 128240-01 3500/42M Prox/Seismic I/O Module, Bently Nevada 3500/42M Proximitor Seismic Monitor, Bently Nevada 125680-01 3500/40M Proximitor I/O Module, Bently Nevada 3500/46M Hydro Monitor, Bently Nevada 3500/72M Recip Rod Position Monitor and Bently Nevada 135489-04 3500/40M Proximitor Internal Barrier I/O.
Documents and quotation
The manufacturer datasheet for the 3500/42M Proximitor Seismic Monitor is attached on this page; read it together with your rack configuration and the site specification before confirming an order. The datasheet lists 176449-02 for the monitor; match the board label on receipt.
Seven Star LLC is an independent supplier in Muscat serving Oman and the GCC. Stock position, lead time, condition and the certificates that travel with the shipment are confirmed in the written quotation.
Datasheets & Documents
- Datasheet Bently Nevada 3500/42M Datasheet Download
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About brand
Bently Nevada is the American machinery protection and condition monitoring brand behind the 3500 rack, the 3300 XL proximity probe and the System 1 software. It was founded in 1961 in Minden, Nevada, and is today a Baker Hughes business.
Seven Star LLC is an independent supplier in Muscat. We list Bently Nevada monitors, I/O modules, probes, proximitors, velocity transducers and transmitters for rotating equipment in Oman and the GCC, and source them by full part number.
Bently Nevada company profile
| Established | 1961, Minden, Nevada, USA, by Donald E. Bently. The business started earlier as Bently Scientific in Berkeley, California (1956). |
|---|---|
| Known for | The first commercial eddy-current proximity transducers for measuring shaft vibration and position on high-speed turbomachinery |
| Ownership | Acquired by GE Energy in 2002; part of Baker Hughes since GE Oil & Gas combined with Baker Hughes in 2017 |
| Rack generations | 5000 series (from 1965), 3300 series (from 1988), 3500 series (from 1995), Orbit 60 (current platform) |
| Product families | Machinery protection racks, proximity probes and proximitors, Keyphasor sensors, velocity and acceleration transducers, 2-wire vibration transmitters, general-purpose monitors, portable analyzers, wireless sensors and System 1 condition monitoring software |
| Typical machines | Steam and gas turbines, centrifugal and reciprocating compressors, pumps, motors, generators, fans and gearboxes |
Milestones
- 1956: Donald E. Bently starts Bently Scientific in Berkeley, California.
- 1961: The company moves to Minden, Nevada, as Bently Nevada.
- 1965: The 5000 series monitoring system is introduced.
- 1988: The 3300 series follows.
- 1995: The 3500 machinery protection system is launched.
- 2002 and 2017: GE Energy acquires Bently Nevada; it becomes part of Baker Hughes in 2017.
Bently Nevada product series
| Series | Type | What it does |
|---|---|---|
| 3500 | Machinery protection rack | Continuous online protection with alarm and danger relays. Modules include the 3500/15 power supply, 3500/20 rack interface, 3500/25 Keyphasor, 3500/42M proximitor/seismic, 3500/50 tachometer, 3500/60 temperature, 3500/33 relay and 3500/92 communication gateway |
| 3500 recip modules | Reciprocating compressor monitoring | 3500/70M impulse velocity, 3500/72M rod position and 3500/77M cylinder pressure |
| Orbit 60 | Protection and monitoring platform | The current Bently Nevada platform for protection, condition monitoring and data integration with System 1 |
| 3300 XL 8 mm | Proximity transducer system | Probe, extension cable and proximitor sensor for radial vibration, thrust position and Keyphasor reference on fluid-film bearing machines; also 5 mm and 25 mm versions |
| 330500 Velomitor, 190501 Velomitor CT | Piezo-velocity sensors | Casing velocity on rolling-element bearing machines and low-speed cooling tower fans |
| 990 and 991 | 2-wire transmitters | 4-20 mA vibration (990) and thrust position (991) signals straight into a PLC or DCS, without a monitor rack |
| 1900/65A, 2300 | Compact monitors | Protection for balance-of-plant pumps, fans and motors where a full 3500 rack is not justified |
A proximity probe measures the gap to the shaft, so it sees shaft movement inside a fluid-film bearing directly. A velocity or acceleration sensor sits on the casing and suits rolling-element bearing machines. Critical turbomachinery usually carries two X-Y probes per bearing, two axial probes for thrust position and a Keyphasor probe for speed and phase.
Where Bently Nevada systems are used
In Oman and the GCC, Bently Nevada racks and probes protect gas turbines, compressors and steam turbines in gas processing, LNG, refining, petrochemical, power and desalination plants. Many installations are 3500 racks that have run for years, so most requests are for like-for-like module, probe, extension cable and proximitor replacements, plus upgrades to newer monitors.
Ordering and replacement: what we need
For probes and proximitors, send the full part number with all option digits (for example 330101-00-27-10-02-05). The digits set the probe length, cable length, connector and approvals, and the probe, cable and proximitor must match in total system length. For 3500 modules, send the module and I/O part numbers from the rack and say whether the I/O is internal or external termination, or barrier type. If a module is obsolete, we quote the replacement that Bently Nevada names and point out any configuration or firmware change.
Facts checked against Baker Hughes Bently Nevada pages and published company history, October 2026.
Browse Bently Nevada products by category: Vibration.
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Frequently Asked Questions
What is the 3500/42M?
It is a four-channel 3500 monitor that accepts proximity, velocity and acceleration transducers and can be programmed for shaft vibration, position, expansion, REBAM, acceleration, velocity and shaft absolute.
How does it differ from the 3500/40M?
The 3500/40M handles proximity transducers only. The 3500/42M adds seismic inputs, so casing vibration and shaft absolute measurement can run in the same module.
Does 140734-02 include an I/O module?
No. It is the front board. A rear I/O module such as 128229-01 or 135489-01 supplies the field terminals.
What outputs does the monitor provide?
A buffered coaxial output per channel on the front panel and a +4 to +20 mA recorder output per channel, which works with 0 to 600 ohm loads.
What temperature range applies?
-30°C to +65°C in general, and 0°C to +65°C when used with the internal barrier I/O module with internal terminations.
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