SLE 2000 HFO, Service Manual, Page: 71 / 258

Issue 10 (01/10/2004) Page 71 of 258
page 164).
15.1.2.3 Ventilator with Version 2 Proximal Airway Purge
The regulator REG 3 should have all four outlet ports used.The proximal airway tube should be
split by a "Y" connector. One limb should run to the proximal airway outlet port, the other limb
should contain another "Y" connector (two limbs of this connector will contain a green plastic
restrictor and the other limb one purple restrictor). Reference Schematic 3. (Also see “AS/
L0203 Sheet 4 of 4” on page 172).
15.1.3 Conventional Ventilation
Air and oxygen supplies are connected directly to the blender. The output from the blender is
supplied via panel mounted regulator REG.1 (0 to 4bar) (inspiratory pressure) and solenoid
valve SV1 to the inspiratory nozzle in the exhalation block. It is also connected to SV3 (the
wave shape solenoid) and the large volume chamber.
In inspiration mode the valve SV1 opens and allows a flow of blended gas into the patient
circuit via the inspiratory nozzle. This flow opposes the constant fresh gas flow and creates an
inspiratory pressure.
The function of the large volume chamber and valve SV3 is to delay this flow of gas during the
inspiratory phase when the waveform taper switch is "on". On expiration SV3 de-energises
and dumps to atmosphere so that the expiratory airway pressure falls rapidly as in square
mode.
REG2 (0 to 4bar)(CPAP) is also supplied from the oxygen blender. This front panel mounted
regulator controls the flow of blended gas from the CPAP nozzle in the exhalation block. This
gas being a constant flow in opposition to the fresh gas flow creates a CPAP/PEEP pressure in
the patient circuit.
NOTE: Any changes of CPAP pressure will also change the peak inspiratory pressure; this is
arranged so that the tidal volume is always constant and unaffected by changes in CPAP.
REG3 (0 to 4bar)is an internal regulator which regulates the blended gas to a working pressure
of 10 psi. NV2 sets a 7LPM bleed to atmosphere. This is to ensure that the oxygen blender has
a constant flow through it at all times to maintain its accuracy.
This bleed is fed to the oxygen monitoring cell, whose output is connected to the digital FIO
2
display circuitry in the electronics module.
RV1 is a pressure relief valve on the Exhalation Block which is activated if the exhalation block
is occluded.
RV2 is a pressure relief valve that is activated if the Fresh Gas port is occluded.
NV1 is adjusted to set a 5 LPM blended gas flow into the fresh gas port on the front panel. This
flow passes through valve SV2 (fresh gas dump solenoid) which will dump the fresh gas
should the patient circuit pressure reach the high pressure alarm threshold. RV2 is a pre-set
relieving valve which prevents pressures greater than approx. 120cmH
2
O developing in the
patient circuit