Service manual

Service Manual 31
675-120 Revision D May 2005
Figure 6 - IFSD Gas Flow Schematic
The patient pressure is shown on the touch screen and is monitored by a pressure
sensor which sends the signal to the main processor. A zeroing valve automatically
checks the pressure readings against atmospheric pressure to ensure accuracy of
the patient pressure readings.
A mechanical pop-off valve is factory set to limit the delivered pressure to a safe
level sufficient to achieve the maximum required patient pressure at the generator.
Adjustment of the pop-off valve is not required by Operators.
Auxiliary Output (Optional)
Blended gas flows through a fixed flow control and non-return valve to a standard
DISS fitting on the back panel to supply a maximum 15 L/min for delivery to the
patient via other sources.
Inspiratory Pressure
Blended gas passes through a variable outlet flow control and through the NCPAP
Pres high flowmeter. The NCPAP Pres high flowmeter is set by the Operator to the
required flow. The outlet from the NCPAP Pres high flowmeter when not delivering to
the patient flows through a restrictor to exhaust, allowing the flowmeter to be
adjusted without delivering gas to the patient. The flow rate is shown on the gauge
on the flowmeter. When the flowmeter control knob is turned fully clockwise, the flow
of gas is turned off. The flow is directed to the patient via a high speed selector valve
which operates when requested by the NCPAP Pres high timing.