SLE SLE2000 HFO User manual

SLE2000 HFO SERVICE MANUAL
DOC NO. SM0001: ISSUE 7.0
Specialised Laboratory Equipment Ltd., Twin Bridges Business Park, 232 Selsdon Road, South Croydon, Surrey, UK. CR2, 6PL.
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CONTENTS
1. INTRODUCTION............................................................................................................................................................5
2. TECHNICAL SPECIFICATION....................................................................................................................................6
2.1 OPERATING MODES...........................................................................................................................................................6
2.2 DISPLAYS .........................................................................................................................................................................6
2.3 CONTROLS........................................................................................................................................................................7
2.4 ALARMS ...........................................................................................................................................................................7
2.5 POWER , DIMENSIONS ETC.................................................................................................................................................8
3. MODULE DESCRIPTIONS ...........................................................................................................................................8
3.1 ELECTRONIC MODULE.......................................................................................................................................................8
3.2 PNEUMATIC MODULE...................................................................................................................................................... 15
4. ACCESS TO THE SLE2000 HFO ................................................................................................................................18
4.1 ELECTRONIC MODULE..................................................................................................................................................... 18
4.2 PNEUMATIC MODULE...................................................................................................................................................... 19
4.3 SEPARATING THE TWO MODULES......................................................................................................................................20
4.4 BACK PANEL...................................................................................................................................................................21
4.5 PNEUMATIC LAYOUT.......................................................................................................................................................22
4.6 REMOVAL OF THE OXYGEN CELL......................................................................................................................................23
4.7 REMOVAL OF THE MOTOR ASSEMBLY................................................................................................................................ 24
5. CIRCUIT DETAILS......................................................................................................................................................26
5.1 A0700/02.......................................................................................................................................................................26
5.2 A0701/02.......................................................................................................................................................................29
5.3 A0702/02.......................................................................................................................................................................32
5.4 A0736/01.......................................................................................................................................................................36
5.5 A0737/01.......................................................................................................................................................................40
5.6 A0738/01.......................................................................................................................................................................43
5.7 A0738/02.......................................................................................................................................................................46
5.8 A0739/01.......................................................................................................................................................................49
5.9 SERIAL INTERFACE OPTION .............................................................................................................................................52
5.10 WIRELOOM...................................................................................................................................................................54
5.11 FRONT PANEL............................................................................................................................................................... 55
5.12 POWER SUPPLY WIRING DIAGRAM.................................................................................................................................56
5.13 ELECTRONIC/PNEUMATIC MODULE INTERCONNECTION...................................................................................................57
5.14 ELECTRONIC CHASSIS ...................................................................................................................................................58
5.15 PNEUMATIC CHASSIS PARTS LIST...................................................................................................................................62
6. SET UP AND CALIBRATION .....................................................................................................................................64
6.1 RECOMMENDED EQUIPMENT............................................................................................................................................ 64
6.2 ELECTRONIC MODULE..................................................................................................................................................... 64
6.3 PNEUMATIC MODULE...................................................................................................................................................... 69
7. OPERATIONAL VERIFICATION ..............................................................................................................................71
7.1 BASIC OPERATION........................................................................................................................................................... 71
7.2 HFO MODULATION......................................................................................................................................................... 72
7.3 DISPLAY TIMEBASE VERIFYING:......................................................................................................................................73
7.4 DISPLAY PRESSURE RANGE VERIFYING:...........................................................................................................................73
7.5 FREEZE PUSH-BUTTON VERIFYING: FREEZE PUSH-BUTTON ..............................................................................................73
7.6 HFO FAIL ..................................................................................................................................................................... 73
7.7 FAN FAIL.....................................................................................................................................................................74
7.8 SLOW RISE WAVEFORM...................................................................................................................................................74

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7.9 PTV MODE ....................................................................................................................................................................74
7.10 SIMV MODE ................................................................................................................................................................74
7.11 BLOCK AND LEAK ALARMS ............................................................................................................................................ 74
7.12 PRESSURE CONTROLS....................................................................................................................................................75
8. MAINTENANCE SCHEDULE.....................................................................................................................................76
8.1 MONTHLY OPERATIONAL CHECKS................................................................................................................................... 76
8.2 SERVICE PROGRAMME.....................................................................................................................................................77
9. CLEANING AND STERILISATION ...........................................................................................................................78
9.1 BACTERIAL FILTERS........................................................................................................................................................79
9.2 EXHALATION BLOCK.......................................................................................................................................................79
10. SLE2000 HFO ELECTRICAL TROUBLESHOOTING CHART.............................................................................80
11. SLE2000 HFO PNEUMATIC TROUBLESHOOTING CHART ..............................................................................81
12. INDEX..........................................................................................................................................................................83

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1. INTRODUCTION
THE SLE2000 HFO PRINCIPLES OF OPERATION
The SLE2000 HFO is based on the patented valveless ventilator design and can be operated in normal
modes of ventilation.
When used as a High frequency oscillatory
ventilator an additional flow of driving gas is
introduced into the exhalation block. This flow
is supplied through a rotating shaft mounted on
a variable speed motor. This flow of driving gas
is adjusted by the oscillatory pressure regulator
mounted in the pneumatic module ensuring a
constant oscillatory pressure waveform at all
operating frequencies. This rotating driving
pressure produces oscillatory action in the
patient circuit with an active expiratory flow of
gas. The oscillatory flow of gas is supplied from
a separate rotating jet, therefore it is possible to
add the oscillations to the inspiration or
expiration pressures. It is also possible to add
oscillations to the inspiratory plateau when
operating the ventilator in any of the Patient
triggered modes of operation.
As in the SLE2000 every care has been taken in the design to ensure the safe operation of the ventilator.
When in use the rotation of the motor is constantly being monitored, should any malfunction be detected in
the HFO operation the flow of oscillatory driving gas will immediately be stopped, and the ventilator will
display motor failure alarm. All other functions of the ventilator such as micro-processors, fans, internal
solenoids and front panel controls are constantly being checked for correct operation.

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2. TECHNICAL SPECIFICATION
2.1 OPERATING MODES
2.1.1 CONVENTIONAL VENTILATION
Modes: OFF,CPAP,CMV,PTV,SIMV
BPM Range: 1-150 breaths per minute
Inspiratory Time: 0.1-3.0 seconds
I:E Range : 9.9:1 - 1:9.9 calculated from BPM and Inspiratory time
settings.
CPAP Pressure: 0cmH2O to 35cmH2O minimum.
Inspiratory Pressure: 0cmH2O to 60cmH2O
switched fast or slow rise waveforms.
2.1.2 HFO VENTILATION
Modes: OFF, EXP, INSP, CONT.
Frequency Range: 3-20Hz. (1Hz resolution.)
Differential Pressure Range: 0 - 90cmH2O peak to peak
Mean Airway Range: 0 - 35cmH2O.
2.2 DISPLAYS
240 × 128 pixel backlit LCD display.
Selectable pressure range: -5 to +60 cmH
2
O or -60 to +60 cmH
2
O
Selectable timebase frame: 6,4,3,2,1,0.5 seconds, showing pressure
waveform, LOW, CYCLE FAIL, HIGH
alarm settings and HFO rate. Freeze
facility.
40 Segment bargraph display: showing pressure waveform, LOW,
CYCLE FAIL, HIGH alarm settings in
the range -10 to +70cmH
2
O. (± 2 cmH
2
O)
Seven segment LED’s: showing BPM, INSP. TIME, I:E RATIO,
FIO
2
and PRESSURE (max., mean or
min.).
Indicator LED’s: MAX., MEAN, MIN. pressures, MUTE,
POWER, TRIGGER BACKUP.
Driving Pressure Gauges:
(Scaled for resultant airway pressures) CPAP/PEEP : 0-40 cmH
2
O
Oscillator : 0-50 cmH
2
O
Inspiratory : 0-60 cmH
2
O

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2.3 CONTROLS
Conventional ventilation mode switch: OFF, ALARM TEST/CPAP, CMV, PTV,
SIMV
BPM Control (ten turn): 1 to 150BPM
INSP. TIME Control (ten turn): 0.10 to 3.00 seconds
(min exp time: 0.25 seconds)
Pressure Display Switch: MAX., MEAN, MIN.
Pressure Display Switch LCD: -5 to +60cmH
2
O or -60 to +60cmH
2
O
Pressure Wave Switch: Slow or Fast rise
Manual Breath Pushbutton
Alarm Mute and Reset Pushbuttons: Mute active for 60 seconds (approx.)
Display Freeze pushbutton: Active for 60 seconds (approx.)
Trigger Sensitivity Control: Range: 2ml/0.5 sec max. To 10ml/0.5sec
min. when using SLE N2188 patient
circuit.
HIGH, CYCLE FAIL, LOW pressure
alarm setting controls: Resolution : 1cmH
2
O on LCD , 2cmH
2
O
on bargraph.
Display Timebase selector switch: 6,4,3,2,1,0.5 seconds/frame
Inspiratory Pressure and CPAP
pressure controls:
HFO Mode Switch: OFF, EXP. INSP. and CONT.
RATE Control: 3 to 20Hz
HFO Pressure Control: 0cmH
2
O to ±45cmH
2
O
CPAP Pressure control: 0 to 35cmH
2
O
Air/Oxygen Blender Control 21-100% ± 3%
2.4 ALARMS
Audible only:
Loss of mains supply: Battery powered alarm
Loss of Air or O2supply: Blender alarm.
Audible and Visual:
HIGH CIRCUIT PRESSURE
CYCLE FAIL
LOW CIRCUIT PRESSURE
FRESH GAS BLOCK
FRESH GAS LEAK or TOTAL GAS SUPPLY FAIL (loss of air and O2).
SYSTEM FAIL: HFO FAIL, FAN FAIL.

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2.5 POWER , DIMENSIONS ETC.
Voltage : 100-250V/ 50-60Hz
Power : 120VA
Fuses : 220-250V~50-60Hz : Fuse T1.0A
100-120V~50-60Hz : Fuse T2.0A
Air and O
2
: 3-5 bar
Operating Environment: Temp: 10-40°C
Humidity: 0-90% (non condensing)
Size, Ventilator only : 37cms W × 39cms H × 32cms D
Height on pole: 141cms
Weight Ventilator Only: 16 Kgs
Constructed to conform to: IEC 601/1 and 601/2
BS 5724 Parts 1 and 2
Patient Circuit Required: Model : N2188 Single use
Model : N2200 Re-usable
3. MODULE DESCRIPTIONS
3.1 ELECTRONIC MODULE
Position of the boards within the
electronic module.
1) HFO Main Board Assembly
(A0736/01)
2) Ventilator CPU Board Assembly
(A0702/02)
3) Motor Drive Board Assembly
(A0739/01)
4) Alarm Board Assembly (A0738) (Not
visible from photo. - mounted on back
panel.)
Note: Boards 1,2, and 3 are polarised by
the position of the edge connectors thus
preventing the boards being inserted into
the wrong sockets.
Board positions within the electronic unit

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3.1.1 FRONT PANEL BOARD ASSEMBLY (A0700/02)
This board is mounted behind the front panel of the SLE2000 HFO Electronic unit and is above the
A0701/02 board. On this board are the seven segment LED displays for; BPM, INSP, I:E, PRESSURE
and FIO2. There are two discreet LED’s on this board for Power (green) and System Fail (red).
3.1.2 LED DISPLAY BOARD ASSEMBLY (A0701/02)
This board is mounted behind the front panel of the SLE2000 HFO Electronic unit and is below the
A0700/02 board. It has a single logic device which is used to drive the max, min and mean LED’s next to
the pressure display switch.
3.1.3 VENTILATOR CPU BOARD ASSEMBLY (A0702/02)
The processor (U14) is an 80C31 microcontroller running at 11.0592MHz. It is an 8 bit processor,
employing time multiplexed address and data operations. Software is provided by the ROM (U6).
Analogue input parameters from panel control settings (BPM rate, inspiration time and high pressure are
converted to digital 8 bit words by the ADC (U18) which scans each input in turn. Open circuit input fault
conditions are detected by software and pull-up resistor array (RU3). Switched input parameters (Mode,
Reset, Mute and Pressure display Mode) are scanned by (U12).
Confirmation of correct solenoid valve energisation voltages is fed to (U14/14) by potential divider R34,
R32 and clamp D3.
Supply voltage supervisor (U7) will attempt to reset the processor (U14/9) should the logic supply voltage
(5.12V dc) fall below (4.8V dc). It also holds the processor reset for a 2 second test period on power up.
Trigger back-up and alarm mute indication LED's are driven by the processor from (U14/5) and (U14/7)
via buffer (U10) and are connected to PLB3a and PLB 15b.
The main PIP solenoid and the waveshape solenoid valve are driven from (U14/8) via buffer (U10) and
MOS driver Q4.
(U1) and (U2) are 7 segment display drivers.
There is a supervisory watchdog alarm system which consists of (U8) and (U3) and BZ2. This monitors a
train of pulses of 20ms period from the processor (U14/3 - the port is toggled every 10ms) to confirm the
correct running of the software. A disruption of these pulses will activate a latched audible alarm BZ2. In
addition, reset pulses from (U7/6) to (U14/9) will attempt to restart the software until the watchdog pulses
are restored.
The Mains Failure Alarm relay-RLl is energised from the 5.12 volt logic supply and holds pins 1 and 14
open. Should the relay de-energise contacts 1 and 14 will close, and a battery powered alarm will be
activated via connections PLB 18a and PLB 20a.

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PTR1 monitors proximal airway pressure in the range -60 to +60 cmH2O. The resultant voltages serve two
purposes:
The first is to present a voltage in the range 1.22V to 4.78V to the ADC U18/26 on the A0702/02 PCB,
for trigger and high pressure fresh gas dump functions.
The second presents a voltage in the range 0.42V to 6.42V to the HFO CPU PCB (A0736/01), to
compare against CPAP, CYCLE FAIL and HIGH PRESSURE alarm settings, and also to drive the LCD
pressure display.
Fresh gas failure pressure transducer PTR2 monitors the fresh gas supply pressure and activates the
audible alarm BZ2 and also drives the leak alarm LED should the pressure fall below 17.5 cmH2O. If the
pressure rises above 80 cmH2O then the block LED is operated and the audible alarm will activate.
3.1.4 HFO MAIN BOARD ASSEMBLY (A0736/01)
3.1.4.1 Motor Stall Alarm
This circuit is active in all HFO modes. Jet rotation is monitored using two opto interrupter devices which
under normal operation shall provide two pulse trains. One of these signals sets a bistable and the other
resets it (U25A and B). The output from the bistable is monitored by an LM2917 tachometer IC (U26).
Should the pulse train stop, then T4 is switched off and the HFO solenoid (SV4) is de-energised thus
cutting off the gas supply to the rotating jet assembly.
In addition, during normal HFO operating conditions, T4 is periodically switched off by T3 in response to
an HFO modulation voltage generated by U21. This uses the I:E solenoid (SV1) energisation voltage to
switch SV4 according to expiratory, inspiratory or continuous HFO modes.
3.1.4.2 HFO Rate
This circuit uses the signal generated by the tachometer circuit (ref 3.1.4.3) to display the HFO rate on the
LCD display. This is achieved by using a TC9401(U20) in a frequency to voltage configuration. The
derived voltage is input to the processor system via the ADC0809 (U5).
3.1.4.3 HFO Pressure Activity Monitor
This circuit uses a voltage representing the pressure wave (taken from the A0702/02 buffered transducer
output) to monitor a minimum level of HFO pressure activity using an LM2917N tachometer IC. The
alarm output is produced when the peak to peak pressure drops below 3cmH2O or the frequency drops
below 3Hz. This circuit is only activated when both CPAP mode and either expiratory or continuous

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modes of HFO operation are selected. In all other modes the alarm is disabled by grounding the output
(U27/5). The output signal is taken to one of the inputs on the Alarm Board (A0738/02).
3.1.4.4 Dual Fan Fail Alarm
This circuit operates audible and visual alarms if the speed of either fan motor falls below approx. 75% of
normal rate. Current pulses from the motor commutation develop pulses which are compared with a
reference voltage in U23A and B. This results in output pulses from U23/1 and U23/7 for each fan. The
negative going edges trigger U22 which remains re-triggered(logic 1) as long as the interval between
triggered pulses is greater than 5ms. The data output of U22 is fed to U24 and is latched in the latter by
the positive going edge of the pulse from U22. The output of U24 remains at logic 0 as long as the interval
between pulses from the motor is less than 5ms. However, if the motor runs slowly or stops or is open
circuit then the output of U24 goes to logic 1 and enables the fan fail alarm via D2 or D3. MOS1 and
MOS4 hold the reset pins of U24 inactive as long as there are motor pulses. U24 is reset during power up
or if motor pulses fail and enables the fan fail alarm.
3.1.4.5 LED Bargraph
This circuit simultaneously displays, on a 40 segment bargraph module, low, fail to cycle, and high alarm
pressure thresholds as well as the instantaneous pressure signal (derived from the A0702/02 buffered
transducer output). These four input voltages are first buffered and conditioned before being time
multiplexed via the 4066 analogue switch (U31). Oscillator U19 drives a counter (U18) which is used to
sequentially enable U31A,B,C and D. The multiplexed signal is then used to drive the bargraph PCB
(A0737).
3.1.4.6 Processor System
All alarm parameters are determined by potentiometer voltages representing fail to cycle, low and high
pressure thresholds. Also Timebase and pressure range switch settings, and CPAP mode status, patient
circuit pressure, HFO motor speed are all represented by voltages which enter the processor system via
addressable ADC0809 (U5)
U7 and its peripheral passive components form a one second interrrupt generator which is used by the
processor system to determine a 1 minute period for the screen freeze function.
The watchdog device U12 will provide a reset pulse for the processor (U10) on power up, power down
and brownout conditions. It will also monitor U13/13, (VIA- Versatile Interrupt Adaptor) and if no
change of state is recognised on this line (indicating a processor fail) within 1.6 seconds then the wathdog
will provide a reset pulse for the processor. Whilst no pulse is recognised on U13/13 the watchdog will
also provide a signal out on U12/14 indicating HFO CPU (A0736/01) system fail which is sent to the
Alarm PCB.
3.1.5 BARGRAPH DISPLAY BOARD ASSEMBLY (A0737)

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This board accepts a time multiplexed signal from the HFO main Board (A0736/01)which contains the
signals for the high, fail to cycle and low alarm thresholds along with the proximal airway pressure signal.
This multiplexed signal is fed into four bargraph drivers (LM3914's) which in turn drive four 10*LED
arrays. For each level of the signal only one of the 40 LED's is illuminated.
3.1.6 ALARM BOARD ASSEMBLY (A0738/02)
3.1.6.1 Alarm Conditioning Circuit
The Alarm circuit comprises U1, U2 and U3. Those alarm inputs which can be muted are input to U2 via a
4066 quad analogue switch (U1), the control pins of which are connected to the mute timer output from
the A0702/02 board PLB/7b. The non mutable alarm inputs go to U2 directly. U2 is an 8-bit comparator
which outputs a logic 1 if any input differs from its reference bit. U3 is a variable gain buffer which drives
audible alarm BZ2.
3.1.6.2 O2Signal Processing
The pneumatic module contains a Galvanic fuel cell which monitors the oxygen concentration delivered by
the blender. The voltage output from this cell is input to U4(LT1006) and associated components, which
condition the cell output voltage to the range 0-4.5V. This voltage is then presented to the ADC U18/4
on the A0702/02 PCB and is used to display the FIO2.
The alarm board also contains a battery powered alarm circuit, consisting of BT1 and BZ3. The circuit is
completed when normally closed relay RL1 on the A0702/02 PCB is de-energised, as would happen in the
event of a power failure.
3.1.6.3 Power Supply Monitor (not on A0738/01 )
The circuit associated with the LM339N quad comparator is set up to give two comparison ‘windows’,
one for the 12V rail being between 11V and 13V and the other for the 24V rail being between 23V and
26V. If either of these rails falls outside the windows then the output transistor is switched on and the
buzzer is activated. The circuit requires the 5.12V supply to be present and will continue to accurately
monitor the 12V and 24V rails until the 5.12V supply drops below the brownout level.

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3.1.7 MOTOR DRIVE BOARD ASSEMBLY (A0739/01)
3.1.7.1 Motor Drive Circuit
U3 is an RC4152 which produces a motor drive frequency proportional to the HFO rate control voltage.
This is used as the clock input to the stepper motor controller L297 (U1) which in conjunction with the
L298N (U2) provides 4 outputs to drive the HFO stepper motor. This circuit is operative in all HFO
modes.
3.1.7.2 LCD Backlight Inverter
This device provides a high voltage a.c. supply to the cold cathode LCD backlight. It is driven by a 12V
d.c. supply.
3.1.7.3 Miscellaneous
Also located on this PCB are the fresh gas solenoid MOS driver (MOS1) and associated components and
a back E.M.F. diode for solenoid SV3.
3.1.8 POWER SUPPLY UNIT
The power supply unit is a universal AC input switcher type. It has an overall power rating of 80W and is
capable of operating down to zero load. It has overvoltage protection on the +5V line which will shut the
unit down. It typically has a hold up time of 75ms.
The pin connections to the unit are as follows;
Plug J1 Description Output Current
1 Ground
2 Neutral
3 Live
Plug J2
1,2,3 +5.12V 8A max, 0A min
4,5,6,7 0V
8,9 +12V 4.5A max, 0A min
10 Power Fail Detect
11 -12V 0.5A max, 0A min
12 key
13 +24V 3.5A max, 0A min
This unit is not servicable.

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3.1.9 GRAPHIC LCD MODULE
The Graphic LCD module is a 240 × 128 pixel display. It incorporates a built-in LCD controller with an
on-board character generator, ROM and RAM. The LCD is a transmissive type with CCFL (Cold
Cathode Flourescent) backlighting provided by a tube mounted on the lower edge of the module.
The cold cathode tube is powered by an inverter mounted on the A0739/01 board. The inverter provides
an ac voltage of 900V rms.
The digital interface to the LCD module consists of a 20 way ribbon cable comprising both data and
control lines. Also the negative voltage for the LCD drive is supplied from this connection.
The unit is not serviceable.

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3.2 PNEUMATIC MODULE
For access to the pneumatic unit see section 4.2 on page 19
Schematic representation of the SLE 2000 HFO pneumatics;
For the physical layout of the pneumatic module see page 21.

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3.2.1 CONVENTIONAL VENTILATION
Air and oxygen supplies are connected directly to the blender.The output of the blender is supplied via
panel mounted regulator REG.1 (inspiratory pressure) and solenoid valve SV1 to the inspiratory nozzle in
the exhalation block. It is also connected to the normally closed port of 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 (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 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 FIO2display
circuitry in the electronics module.
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. 120cmH2O developing in the patient circuit.
Both the SLE2000 single use patient circuit (N2188) and the reuseable patient circuit (N2220) incorporate
a restrictor close to the inspiratory port of the ET connector. This generates a nominal 20cmH2O pressure
in the fresh gas supply system as long as there are no leaks. Pressure transducer PTR2, located on the
A0702/02 PCB, monitors the fresh gas pressure and associated circuitry will activate a leak alarm should
this pressure fall below 17.5cmH2O and activate a block alarm if the pressure rises above 80cmH2O.
3.2.2 HFO OPERATION
HFO pressure is determined by a 0-4Bar panel mounted pressure regulator REG4, resulting in HFO peak
airway pressures in the range 0 to ±45cmH2O. The HFO driving gas stream is rotated in the exhalation

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block by the rotating nozzle assembly at a rate determined by the HFO motor speed. Solenoid valve SV4
is de-energised in the event of a motor drive failure, thus cutting off the HFO driving gas pressure. SV4
also serves to modulate the HFO driving gas pressure in various ways during conventional ventilation; that
is, during the inspiratory phase or during the expiratory phase, thus allowing combined modes of HFO and
conventional ventilation.

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4. ACCESS TO THE SLE2000 HFO
The SLE 2000 HFO consists of two linked modules, Electronic and Pneumatic
4.1 ELECTRONIC MODULE
1) Remove 2 screws at rear and 2 screws at either side of the unit.
2) Slide top cover to the rear and remove.
3) To remove the PCB assemblies, remove retaining thumbscrews (one for each board) next to the edge
connector.
4) Disconnect all pneumatic and electrical connections to the board and pull board out.

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4.2 PNEUMATIC MODULE
Caution: All electrical and pneumatic connections must be disconnected before attempting to gain access
to either the Electronic or Pneumatic modules.
1) Open side flap.
2) Remove 2 screws at rear and 2 screws at base of unit.
3) Lift complete unit from base.
The unit can then be placed on the work surface upside down. (See page 20 )

SLE2000 HFO Service Manual
Doc No. SM/0001: Issue 7.0 Page 20 of 84
4.3 SEPARATING THE TWO MODULES
a) Invert the ventilator to gain access to the base of the pneumatic unit (see page 19 )
b) Remove the four screws (1)
c) Remove proximal airway pressure tube connection (2)
d) Remove fresh gas monitoring tube connection (3)
e) Loosen both locking screws (4) and disconnect 25 way plug.
It is now possible to separate the pneumatic module from the electronic chassis.