Bently Nevada 330400, 330425 Specifications

330400 and 330425 Accelerometer
Acceleration Transducers

Datasheet

Bently Nevada Machinery Condition Monitoring

Description

These accelerometers are intended for critical machinery
applications where casing acceleration measurements are
required, such as gear mesh monitoring. The 330400 is
designed to address the requirements of American
Petroleum Institute Standard 670 for accelerometers. It
provides an amplitude range of 50 g peak and a sensitivity of
100 mV/g. The 330425 is identical except it provides a larger
amplitude range (75 g peak) and a sensitivity of 25 mV/g.

If housing measurements are being made for overall
protection of the machine, thought should be given to
the usefulness of the measurement for each
application. Most common machine malfunctions
(imbalance, misalignment, etc.) originate at the rotor
and cause an increase (or at least a change) in rotor
vibration. In order for any housing measurement
alone to be effective for overall machine protection, a
significant amount of rotor vibration must be faithfully
transmitted to the bearing housing or machine
casing, or more specifically, to the mounting location
of the transducer.

141638 Rev. Y

In addition, care should be exercised in the physical
installation of the transducer. Improper installation can result
in a degradation of the transducer’s performance, and/ or
the generation of signals which do not represent actual
machine vibration. Integration of the output to velocity can
worsen this. Extreme caution should be exercised if
integrating to velocity. For high quality velocity
measurements the 330500 Velomitor Sensor should be used.

Upon request, we can provide engineering services to
determine the appropriateness of housing measurements for
the machine in question and/or to provide installation
assistance.

330400 and 330425 Accelerometer Acceleration Transducers
Datasheet 141638 Rev. Y

Both Units

Specifications

Parameters are specified from +20 to +30 °C
(+68 to +86 °F) and 100 Hz unless otherwise
indicated.

Operation outside the specified limits may
result in false readings or loss of machine
monitoring.

Electrical
330400

Sensitivity

Acceleration
range

Amplitude
Linearity

Broadband
Noise Floor
(10 Hz to 15
kHz)

10.2 mV/m/s2 (100 mV/g) ±5%.

490 m/s2 (50 g) peak overall
acceleration within the 10 Hz to 15 kHz
frequency span. Vibration at
frequencies above 15 kHz, especially
at the transducers resonance will
significantly decrease this range.

±1% to 490 m/ s2 (50 g) peak.

0.039 m/s2 (0.004 g) rms.

10 Hz to 15 kHz

Frequency
Response

Temperature
Sensitivity

Transverse
Sensitivity

Mounted
Resonant
Frequency

Amplitude of
Resonant
Peak

Base Strain Sensitivity

For serial
numbers
preceded by
the letter “G”
(including all
new sensors

(600 cpm to 900,000 cpm) ±3dB;

30 Hz to 10 kHz

(1800 cpm to 600,000 cpm) ±10%

-11% to +3% typical over the
operating temperature range.

Less than 5% of axial.

Greater than 30 kHz.

20 dB maximum.

49 mm/s2/mstrain (0.005
g/mstrain)

980 mm/s2/mstrain (0.100
g/mstrain) without Mounting Base
(API adapter);

330425

Sensitivity

Acceleration
Range

Amplitude
Linearity

Broadband
Noise Floor
(10 Hz to 15
kHz)

2.5 mV/m/s2 (25 mV/g) ±5%.

735 m/s2 (75 g) peak overall
acceleration within the 10 Hz to 15 kHz
frequency span. Vibration at
frequencies above 15 kHz, especially
at the transducer’s resonance, will
significantly decrease this range.

±1% to 735 m/s2 (75 g) peak.

0.098 m/s2 (0.01 g) rms.

For serial
numbers NOT
preceded by
the letter “G”
(shipped prior
to April 2004)

Maximum
cable length

Power requirements

Input Voltage -24 ± 0.5 Vdc.
Bias Current 2 mA nominal.
Output Bias

Voltage:
Grounding Case isolated.

4.9 mm/s2/mstrain (0.0005
g/mstrain) with Mounting Base (API
adapter) supplied with the
accelerometer.

Bently Nevada recommends
installing with the Mounting
base to minimize base strain
sensitivity for serial numbers
NOT preceded by the letter
“G”.

305 metres (1000 ft) with no
degradation of signal.

-8.5 ± 0.5 Vdc.

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330400 and 330425 Accelerometer Acceleration Transducers
Datasheet 141638 Rev. Y

Environmental Limits

Operating
and storage
temperature

Shock
Survivability

Relative
humidity

Magnetic
Field
Susceptibility

IP Rating

-55°C to +121°C (-67°F to +250°F)

49,050 m/s2 (5000 g) peak,
maximum.

100% condensing, non-submerged.
Case is hermetically sealed.

<2.21 mm/s2/gauss (225 mg/gauss)
[50 gauss, 50-60Hz].

Equivalent to an IP 68 (Dust tight and
watertight). Please note that this is
for the sensor only and does not
apply to the cable.

Physical

Weight (no
cable)

Diameter 23 mm (0.93 in).

Height

Connector

Mounting
Surface

Mounting
Torque

Case Material 316L stainless steel
Weight (no

cable)
Mounting

Angle

99 g (3.5 oz), typical

59 mm (2.3 in), including mounting
stud.

3-pin MIL-C-5015 Receptacle
316L stainless steel

32 minch rms.

4.1 N·m (3.0 ft·lb).

100 g (3.5 oz), typical

Any orientation

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