Repair Information
27
2.14.1 Ventilator pneumatic drive
Air or Oxygen, in the CMV mode, serves as driving gas for the ventilator. In addition to the flow meter
block, a pressure reducer, reducing the supply pressure to 200 kPa (2 bar; 29 PSI), is supplied by the
Air or oxygen connection. This pressure represents the high system pressure of the ventilator. The
pressure reducer is named HP pressure reducer.
The HP pressure reducer is placed ahead of the proportional valve that generates the driving gas flow
during the inspiratory phase. This flow is led through the flow divider and fills the bellows dome that
surrounds the silicone bellow.
In response to the inspiratory and expiratory phases of a respiration cycle, the pneumatic valves
(diaphragm valves) of the patient module are activated by solenoid valves.
These solenoid valves, MV1, MV3, and MV2 are supplied by a second pressure reducer assembly
(LP- double stage pressure reducer) at the low system pressure, together with MV4, with about 20 kPa
(200 mbar; 2.9 PSI)// 25 kPa (250 mbar; 3,63PSI).
Cyclic activation of the proportional valve and solenoid valves is steered by the processors of module
2 according to the parameters set on the control panel of the ventilator.
A description of the individual components will be found in the following chapters:
2.14.2 HP pressure reducer
The HP pressure reducer serves for a stabilization of the supply pressure for the proportional valve.
The flow generated by the proportional valve thus becomes independent of pressure variations.
The setting of the HP pressure reducer (200 kPa (2 bar; 29 PSI)) at the same time determines the
maximum inspiratory flow of 75 +0/-4 L/min with respect to the respirator.
2.14.3 LP- double stage pressure reducer
This pressure reducer assembly is supplied with oxygen in parallel to the measuring tube block or ratio
system, respectively. It reduces the input pressure to 20 kPa (200 mbar; 2.9 PSI)// 25 kPa (250 mbar;
3,63PSI), and is connected to the solenoid valve bank.
2.14.4 Solenoid valves MV1 to MV4
The solenoid valves MV1, MV2, MV3 and MV4 are mounted on a bank behind the patient module
docking station to which the tubes to the docking station of the patient module and the LP- double
stage pressure reducer are connected.
MV1: This solenoid valve activates, in the CMV mode, the valve for closing the outlet of the bellows
dome (bellows control valve) through the line 5, when driving gas flows in for inspiration. It is supplied
by the LP- double stage pressure reducer.
MV2: This solenoid valve activates, in the CMV mode, the valve closing the expiratory channel of the
patient module (expiratory valve), via MV2 through the line 1. It is supplied by the LP- double stage
pressure reducer via MV4.
MV3: This solenoid valve activates, in the CMV mode, the valve for the fresh gas decoupling
(decoupling valve) through the line 6. It is supplied by the LP- double stage pressure reducer.
MV4: This solenoid valve is used for internal supply of MV2 with pressure of the LP- reducer.
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