CareFusion Bird Sentry User Manual page 35

Bird Sentry™ Blender
Mix ing Operation
The Bird Sentry blender is designed to utilize two (2) 50 PSIG (3.4 BAR) gas sources. The two (2) gas
sources enter through the diameter indexed air and oxygen inlet connectors located on the bottom of
the Bird Sentry blender.
Each inlet connector incorporates a 30 micron particulate filter. Once through the filters, each gas
passes through a duckbill check valve which prevents possible reverse gas flow from either the air or
the oxygen supply systems.
The two (2) gases then pass through a two-stage balance regulator. The purpose of this regulator is to
equalize the operating pressures of the air and oxygen gas sources. Once these pressures have been
balanced, the gases are proportioned according to the oxygen concentration selected on the oxygen
concentration selection knob. The oxygen concentration knob allows the clinician to select a desired
oxygen concentration from 21% to 100% O
Gas Outlet
There are two (2) gas outlets on the Bird Sentry blender: one on the bottom of the unit and one on the
left side (facing the unit). These outlets are capable of delivering combined metered flows of 2-100
liters per minute (LPM) of mixed gases. These outlet ports are fitted with an automatic shut off valve.
The flow of gas from either outlet port is automatically initiated by attaching a pneumatic device (such
as a flow meter) to the outlet port. Regardless of whether or not the outlet has any device connected
to it, a minimal gas bleed flow of 1143 LPIVI flows from the sensor port on the right side of the Bird
Sentry blender. It is from this bleed flow that the gas is sampled and analyzed by the Bird Sentry
analyzer and monitor functions.
Alarm/ By pass Function
The Bird Sentry blender includes a pressure differential alarm which provides an audible alarm if gas
source pressures differ by 20 PSI (1.3 BAR) (nominal) or more, or if there is a gas supply failure of one
of the source gases. This alarm is generated by a reed alarm located in a cap on the bottom of the Bird
Sentry blender. The primary purpose of the alarm is to audibly warn the operator of an excessive
pressure drop or depletion of either source gas pressure. The alarm will also activate when there is an
elevation of either source gas pressure resulting in a differential of 20 PSI (1.3 BAR)(nominal) or more.
Should both gas pressures increase or decrease simultaneously, an alarm will not activate. If either
source gas pressure drops, the outlet pressure will drop similarly as the mixed gas is always balanced to
that of the lower gas source.
The gas bypass function operates in unison with the alarm. Once the pressure alarm is activated, the
bypass function is actuated and the gas with the higher pressure flows directly to the outlet port,
bypassing the mixing function of the Bird Sentry blender. The oxygen concentration flowing out of the
Bird Sentry blender will be that of the gas with the higher pressure. The Bird Sentry blender in the
pressure alarm/bypass mode will deliver oxygen (100%) or medical air (21%) until pressures have been
restored to a differential of 6 PSI (.4 BAR).
If the Bird Sentry blender is set to deliver 21% and the OXYGEN source pressure is reduced enough to
produce a 20 PSI (1.3 BAR) differential, the unit may not alarm because it will continue to deliver 21%
concentration according to the setting. If the setting is moved slightly from 21%, the pressure
differential alarm will sound. Similarly, if the Bird Sentry blender is set to deliver 100% and the AIR
source pressure is reduced or lost, the unit may not alarm because it will continue to deliver 100%
concentration.
L1383 Rev. D
. From this point, the mixed gas flows to the outlet port.
2
Chapter 7: Appendices
23