Datex-Ohmeda CAPNOMAC ULTIMA, Service Manual

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CAPNOMAC ULTIMA
TM
SERVICE MANUAL
5-53
5.13 PVX board
Block diagram and schematic diagram part 1
Parts layout and schematic diagram part 2 Figure 5.26
Figure 5.27
NOTE:
Pressure transducers Bl , B2, and EEPROM D4 are
replaced only at the factory.
NOTE:
Never apply overpressure or negative pressure of more
than 300 cmH
2
O to the flow and volume tubing.
The board is intended to perform the following tasks
Measure the pressures in airways and the speed of
breathing flow.
Calculate tidal volume, minute volume, compliance and
other useful information on a patient lungs.
Pressure transducers
There are two pressure transducers on the PVX board for airway
pressure measuring purpose.
The breathing flow of a patient passing through D-LITE
TM
creates pressure difference. This pressure difference is measured by
pressure transducer, Bl. Overpressure and negative pressure in
airways are measured by another pressure transducer B2.
Signal amplification
After the transducer B2 the PRESS-signal is sent to differential
amplifier A6, whose gain is 375, which contains low pass filter
suppressing signals over 31 Hz. Then the signal is sent to the
multiplexer A9 through voltage follower A7.
After the transducer Bl the FLOW-signal is sent to differential
amplifier, A5 and A4, whose gain is 27 and which contains low
pass filter where signals over 30 Hz are suppressed. After the filter
the signal is fed to another amplifier A3, whose gain is 11 and who
contains a low pass filter which suppresses signals over 48 Hz.
From this point the signal (FLOW0) goes two different ways: one
goes straight to the multiplexer A9 (FLOW0). Another goes yet to
the third amplifier A3, whose gain is 11 and which contains a low
pass filter of 72 Hz. This sensitive signal (FLOWl) is also sent to
the multiplexer A9.
January 15th, 1997/6