Introduction
The Bently Nevada 990-04-XX-01 is a model from the Bently Nevada 990 series of Velocity Seismic Transducers. The "XX" in the part number typically represents a variable code that specifies the frequency response of the sensor (e.g., -70 for 4.5 Hz to 450 Hz, -71 for 4.5 Hz to 1000 Hz). This device is designed for continuous monitoring of absolute casing vibration on a wide range of industrial machinery.
This transducer is a passive, self-generating sensor that operates on the electromagnetic induction principle. It contains a permanent magnet seismic mass suspended by springs within a coil. When the transducer's casing vibrates, the coil moves relative to the magnet, generating an analog voltage output signal directly proportional to the vibration velocity. It requires no external power, making it simple, robust, and ideal for monitoring machines like pumps, motors, and fans.
Parameters / Specifications
The key technical specifications for a typical Bently Nevada 990-04-XX-01 are summarized in the table below.
| Parameter | Specification |
|---|---|
| Part Number | 990-04-XX-01 (e.g., 990-04-70-01, 990-04-71-01) |
| Product Line / Type | Bently Nevada 990 Series Velocity Seismic Transducer |
| Measured Parameter | Casing Vibration Velocity |
| Sensitivity | 100 mV/in/s (This is a key interpretation of the -04 suffix) |
| Frequency Response | Varies (e.g., 4.5-450 Hz or 4.5-1000 Hz) depending on the "XX" code |
| Amplitude Range | 0 to 1.0 in/s (0 to 25.4 mm/s) peak (typical) |
| Output Signal | Analog Voltage (self-generating, no external power required) |
| Power Supply | None (Passive device) |
| Electrical Connection | Integrated, unconnectorized cable (This is a key interpretation of the -01 suffix) |
| Mounting | Single 1/4-28 UNF threaded stud on the base. |
| Housing Material | Stainless Steel |
| Sensing Orientation | Specific to one axis (uniaxial). Must be mounted in the correct orientation. |
| Dimensions (Approx.) | Diameter: ~1.9 in (48 mm), Height: ~2.4 in (61 mm) |
| Weight (Approx.) | 1.1 lbs (0.5 kg) |
| Operating Temperature | -50°C to +120°C (-58°F to +248°F) |
Note: The exact frequency range and other minor specifications are determined by the "XX" suffix. Consulting the official Bently Nevada 990 series datasheet for the specific variant is recommended.
Application Scenarios
This velocity transducer is a versatile workhorse for general-purpose machinery condition monitoring, providing reliable vibration data for predictive maintenance programs.
Typical Application Scenarios:
Motor and Pump Casing Monitoring:
Permanently installed on the bearing housings of critical motors, centrifugal pumps, and fans to detect overall vibration levels caused by imbalance, misalignment, and bearing defects.
Fan and Blower Monitoring:
Mounted on the casings of large induced draft (ID) and forced draft (FD) fans in power plants and HVAC systems to monitor for vibration due to fouling, imbalance, or mechanical looseness.
General Machinery Health Assessment:
Used for periodic or continuous monitoring on a wide range of industrial machinery, such as compressors, gearboxes, and machine tools, to provide a trendable velocity signal.
Non-Critical Equipment Protection:
Providing a cost-effective solution for alarm and shutdown protection on general-purpose machines where a full eddy current system is not economically justified.
Industries of Use:
Power Generation (for auxiliary equipment)
Water and Wastewater Treatment
Chemical and Petrochemical Processing
HVAC
General Manufacturing and Heavy Industry
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