Welch Allyn Duet CO2 Module - User Manual - Manual (Page 17)

Duet CO
2
Module OEM Implementation Manual
Welch Allyn OEM Technologies Confidential Page 17
Sidestream Components
The functional components necessary for sidestream operation include
§ sidestream daughter board
§ pump
§ Water trap assembly and receiver
§ inlet and exhaust tubing
§ CO
2
sample line/cannula
Sidestream Daughter Board
The sidestream daughter board provides the interface to the sidestream CO
2
sensor; pump and Water
trap receiver switch; controls to start and maintain the chopper motor speed; and provides feedback to
regulate the pump flow.
The functional components of the sidestream daughter board include the sidestream bench, the motor
control hybrid (refer to Mainstream Components section), the flow control circuitry and the pump and
Water trap assembly connectors.
Apart from the absence of a heater, the sidestream bench operates in the same manner as the
mainstream sensor. Additionally, the microprocessor monitors the internal sensor temperature through
thermistor feedback to compensate for temperature variation.
The flow control circuitry regulates flow using a fixed orifice flow sensor that provides feedback to a
circuit controlling power to the pump. A differential pressure transducer measures the pressure drop
across a restrictor. It is used as feedback to adjust the pump speed. The pump power supply steps
down the raw voltage applied to the board to a level appropriate for maintaining the desired pump flow
rate.
The pump connector provides electrical connection of the pump to the sidestream daughter board.
The Water trap assembly connector provides electrical connection of the Water trap switch to the
sidestream daughter board.
Pump
The electrically driven miniature oil-free diaphragm pump draws the sample through the sample line to
the sample chamber by creating a vacuum. Fault states such as exhaust and Water trap occlusions are
recognized by the flow control circuitry.
Water trap Assembly
The Water trap assembly provides the principal filter medium for the airway gas sample before the gas
is delivered to the sample chamber.
The functional components of the Water trap assembly include the Water trap, the Water trap receiver
and the Water trap receiver switch.
NOTE Water trap, Water trap receiver and Water trap receiver switch are not included with the
MS/SS and SS Duet CO
2
Modules and may be ordered separately from Welch Allyn OEM
Technologies or supplied by the OEM.