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MAJOR COMPONENTS
a. Oxygen Blender. The oxygen blender (figure 1-2) precisely controls oxygen
concentrations delivered to the Babybird ventilator. It requires reliable sources of air and
oxygen to function properly. Control of source-gas pressure is important as the blender
delivers gas mixtures at about 2psi below the lowest source-gas pressure. The
ventilator requires a minimum of 45psi source pressure to operate. Minor differences in
incoming pressures are compensated for within the blender. Both air and oxygen
pressures are precisely balanced by dual pressure regulators and controlled by a
calibrated proportioning valve. Use the control knob to set the exact oxygen and air
mixtures for required concentrations of oxygen. If one of the gas supplies fail, the
blender allows the other gas to continue to flow to the patient and sounds an alarm to
warn of the failure. The alarm system consists of two diaphragm operated poppet
valves, one of which opens and allows gas pressure to overcome spring tension on the
valve and direct one of the gases to the audible alarm. When the ventilator is first
activated, the alarm sounds until both air and oxygen pressures are equalized in the
blender.
Figure 1-2. Oxygen blender and alarm.
MD0355
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