CWE BPM-832 User manual
BPM-832
Dual Channel Transducer Amplifier
©CWE 2024
Read instructions carefully before operating this device.
This device is not to be used for Human Life Support applications.
To avoid possible electrical shock, do not operate this device if is wet or has had liquids spilled onto it.
Service or calibration procedures should only be performed by qualified personnel familiar with the
electrical hazards of line-powered devices.
Instruction Manual
www.cwe-inc.com
BPM-832 Instruction Manual 2
© 2024 CWE, Inc.
STATEMENT OF WARRANTY
IF THIS INSTRUMENT FAILS WITHIN A PERIOD OF ONE YEAR FROM THE DATE OF
DELIVERY OR INSTALLATION, CWE, INC. WILL, AT ITS OPTION, REPAIR OR
REPLACE IT FREE OF CHARGE. THIS WARRANTY EXCLUDES DAMAGE
INCURRED THROUGH MISUSE OR ACCIDENT. CWE, INC. DOES NOT ASSUME ANY
LIABILITY FOR ANY CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OF
THIS INSTRUMENT.
DEFECTIVE UNITS SHOULD BE RETURNED TO THE FACTORY ALONG WITH A
NOTE DESCRIBING THE NATURE OF THE FAULT. THIS WARRANTY IS
APPLICABLE TO THE ORIGINAL PURCHASER OF THE INSTRUMENT ONLY, AND IS
NOT TRANSFERABLE.
FACTORY SERVICE
Out of warranty or damaged instruments may be returned to the factory freight prepaid
for service at prevailing rates. Upon request, a written or verbal quotation for such service
will be issued after examination of the unit but prior to commencing repairs or service.
Address requests for service or technical information to:
CWE, Incorporated
Technical Support
Ardmore, PA 19003 U.S.A.
(610)642-7719
LIFE SUPPORT POLICY
Instruments manufactured by CWE, Incorporated are not authorized for use as critical
components in human life support devices or systems. "Life support devices or systems",
as used herein, are devices or systems whose failure to perform, whether through misuse,
failure, or proper operation, can reasonably be expected to result in significant injury to
the operator or subject persons.
This manual last updated on 2/14/24
BPM-832 Instruction Manual 3
© 2024 CWE, Inc.
1.0 INTRODUCTION
The BPM-832 is a dual-channel instrument for monitoring the output of strain-
gage pressure transducers. A wide gain range and stable excitation and
balancing circuit make the unit suitable for monitoring blood, airway, or other
pressures in the laboratory. In addition, many force and acceleration
transducers can also be used with the BPM-832. A direct-reading digital
readout is provided for each channel, along with an analog output for external
display or recording of the pressure signal. Adjustable low-pass filters include
a mean pressure function. The BPM-832 is compatible with most strain-gage
transducers using DC excitation.
Figure 1: Front panel view of BPM-832, showing the two identical sets of controls.
BPM-832 Instruction Manual 4
© 2024 CWE, Inc.
2.0 SPECIFICATIONS
Transducer compatibility ...................................Statham, Gould, Grass
Transducer type required................................................resistive bridge
Input connector............................................................Canon WK6-32S
Excitation voltage.............................................. 4 –10VDC (adjustable)
Pressure range.........................................Depends on transducer used
Balance ranges................................. +/-.010, +/-.100, +/-.500V, 10-turn
Decade Sensitivity Switch..........................................X10, X100, X1000
Size vernier..................................................... 10-Turn, 0-1X attenuator
Low-pass filter ........................................6 position, -12dB/octave slope
Filter frequencies........................0.1 (Mean), 10, 50, 100, 200, 5000Hz
LCD Digital display .............................3 ½ digits, 0-1999 pressure units
Analog output ..........................................................................0-1.999V
Output connector....................................................................BNC Jack
Dimensions.....................................................3H x 9.5W x 7.5D inches
Power requirements.......................................................120V/60Hz, 5W
3.0 INSTALLATION
The included power supply should be plugged into a 3-wire grounded electrical
outlet. Plug the cord from the power supply into the POWER jack on the rear of
the case. The pressure transducers to be used are plugged into the
TRANSDUCER connectors on the front panel.
4.0 OPERATING CONTROLS
4.1 POWER SWITCH
This switch turns on the power to the instrument. When switched
ON, the digital display and the red LED will turn on, indicating that
the instrument is receiving power. If the meter does not come on,
check that the electrical outlet is working properly.
4.2 TRANSDUCER INPUT
The pressure transducer to be used is plugged into the
TRANSDUCER connector. This connector is compatible with
Gould, Statham, Electronics for Medicine, CWE Series PS-1000
and other transducers. If your transducer has a different connector,
adaptor cables are available from CWE, Inc. or from Fogg Systems.
BPM-832 Instruction Manual 5
© 2024 CWE, Inc.
For reference, the input connector uses the following pin
connections:
PIN No.
Function
1
+ excitation voltage
2
+ signal
3
- signal
4
- excitation voltage
5
Not used
6
shield
4.3 BALANCING
Balancing the transducer is necessary to offset any small DC voltage
present on the strain-gage with a zero pressure input. First allow the BPM-
832 to warm up for about five minutes with the transducers connected.
Adjust the BALANCE dial until a zero reading is observed on the digital
meter. The transducer is now balanced.
4.4 SENSITIVITY SETTING
The SENSITIVITY and SIZE controls are used to make the displayed
pressure correspond to actual engineering units. A wide gain range is
available to permit calibration in cmH2O, mmHg, or other desired units. A
three-position decade SENSITIVITY switch works in conjunction with a 0-
1X SIZE knob.
Before calibrating the unit, be sure the transducer is balanced (see Section
4.3). For most applications, the MED range should be selected. Using a
manometer or other known pressure source, apply pressure to the
transducer. Adjust the SIZE knob until the displayed reading corresponds
to the actual applied pressure. Try to find the SENSITIVITY range that
allows the SIZE control to be positioned somewhere near its midrange,
rather than at either extreme of its adjustment.
Note the the full-scale output of the BPM-832 is +/-1.999V. This is also the
full-scale range of the digital panel meter (1999 units). To get the maximum
resolution, adjust the gain controls so as to give a maximum expected
reading of close to 2V. For example, if monitoring a pressure with an
expected maximum reading of about 100cmH2O, you could adjust the
SENSITIVITY controls to give a reading of 100 on the meter with a
100cmH2O. To obtain the best resolution however, adjust the gains to give
a reading of 1000, which now reads directly in mmH2O, thus giving you ten
times more resolution.
BPM-832 Instruction Manual 6
© 2024 CWE, Inc.
4.5 FILTER
The low-pass filters built into the BPM-832 allow the user to attenuate
unwanted high-frequency noise or artifacts which may be present on the
pressure signal. The filter cutoff frequency should be selected to limit the
signal to frequencies of interest. The lowest setting, 0.1Hz, gives a mean
pressure reading, and is thus useful for monitoring mean blood pressure.
4.6 DIGITAL PRESSURE METER & ANALOG OUTPUT
The front-panel digital meters display the pressure readings in arbitrary
units, up to 1999. It is up to the user to calibrate the instrument so that the
display reads out in meaningful units (see Section 4.4). The displayed
reading corresponds to the analog OUTPUT voltage in millivolts. Thus, a
reading of 249 on the meter corresponds to an OUTPUT voltage of 249mV,
or 0.249V. Note that the meter reading (and the OUTPUT voltage) is
bipolar: positive and negative pressure signals are indicated correctly.
5.0 ORDERING INFORMATION
Many commercially available pressure, force, and acceleration transducers are
compatible with the BPM-832 Pressure Monitor. To use transducers with a
different cable connector than the Cannon WK6-32S, adaptor cables are available
from the following source: Fogg System Company, Aurora, CO 80011
Part No.
Model
Description
08-12000
BPM-832
2-Channel Pressure Monitor with power supply
10-04010
PS-1000/A-1
Differential Pressure Transducer (+/-70cmH2O)
10-04011
PS-1000/A-004
Differential Pressure Transducer (+/-10cmH2O
10-04100
DTX-1
Standard medical grade BP Transducer
10-04110
DTX-10
Pack of 10 standard medical grade BP Transducers
10-04210
TC-GRA
Required adapter cable for DTX-1 BP Transducers
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