Part 2 SES 2000 Vac (LS3) AUTOCLAVE
Page 8 of 53 ST-SM45g
PART 2 DESCRIPTION
❑Water Filter. The water filter is fitted on the end of
the water fill pipe in the water reservoir, and filters
thewaterenteringthechamber.
❑ReservoirFloatSwitch(Fig.2.3,item11). Thewater
reservoir is fitted with a float switch which will stop
the cycle being started if there is insufficient water
in the reservoir to complete a chamber fill. ‘Fill
Reservoir’ will be displayed should this occur.
❑Heating Element (Fig. 2.4, item 1). The heating
element consists of a single immersion element
insidethechamber.Theheatingelementiscontrolled
byasolidstaterelayandprotectedfromoverheating
byamanualreset thermostat.RefertoTECHNICAL
DATAforheaterelementloading.
❑Solid-State Relay Board (Fig. 2.4, item 14). See
AppendixB. Thereareanumberof keyfunctions
providedbytherelay board:
wSolid state relays (SSR) control the mains
supplytothewaterheaterelement(10A),band
heater(10A)andvacuumpump(2A).
wSSR status LEDs, give an indication of drive
status (On/Off).
wMechanical relay provides additional safety
for heater and pump circuits.
wFusesforprotectingthe20Va.c.supply(3.15A),
condenser fan (2A) and vacuum pump (5A)
see 'Parts List 3'.
wTwovoltageregulators.
wAutoclavebleeper.
wConnections for mains loom, signal loom,
temperature and pressure sensors, solenoid
valves,andtransformer.
wInterface for front panel, control board, and
printer.
❑ManualResetOverheat Cutout(Fig.2.4,item21).
Themanualresetoverheatcutoutisfittedattherear
oftheunitandisconnectedinserieswiththepower
supply switch, band heater overheat cutout,
mechanicalandSSrelayandheater element. The
manualresetoverheatcutoutisoperatedbyafluid-
filled capsule clamped to the heating element,
providingprotectionifthetemperature oftheheater
surfaceexceeds250°C.Itwillremakeelectricallyif
theresetbuttonattherearofthecabinetispressed,
after giving the heater element time to cool.
❑Band Heater Overheat Cutout (Fig. 2.4, item 24).
Thebandheatercutoutisfittedontheband heater
and is connected in series with the power supply
switch,ManualResetOverheatCutout,mechanical
and SS relay and Band Heater. It contains a bi-
metallic disc thermostat which operates if the
temperatureoftheheatersurfaceexceeds 250°C.
Thecutoutwillremakeelectricallyiftheresetbutton
is pressed when the heater has cooled.
❑Fuses. The unit has five fuses:
wTwo fuses (Fig. 2.4, item 2) on the rear panel
ofthecabinetratedasshowninTECHNICAL
DATA, which are connected in the ‘mains
supply’ to the unit.
wThreemorefuses are fitted on the solid-state
relayboard(seeTECHNICALDATA).
❑Transformer (Fig. 2.4, item 17). The transformer
convertstheincomingmainsvoltageto24Va.c. It
is rated at 50VA.
❑Water Fill Solenoid Valve (Fig. 2.3, item 4). The
waterfillvalvecontrolsthewaterfillsequence. Itis
electrically operated from the 24V d.c. supply
generatedandsignalledfromtheSSRboard.
❑WaterDischargeSolenoidValve(Fig. 2.3, item3).
Thewaterdischargevalveisusedattheendofthe
sterilizing cycle to allow water and steam vapour
from the chamber to pass back into the reservoir.
The valve is electrically operated from a 24V d.c.
supplygeneratedandsignalledfromtheSSRboard.
❑Discharge Line Filter (Fig. 2.3, item 12). Prevents
debris from the chamber entering and fouling the
waterdischargevalve.
❑SteamBleedSolenoidValve(Fig.2.3,item2). The
steambleedsolenoidvalveoperatesinconjunction
with the steam bleed valve.
❑Steam Bleed Valve (Fig. 2.3, item 15). The steam
bleed valve is connected in series with the steam
bleedsolenoidvalvetobleedsteamfromthechamber
during the 121°C cycles. It contains a ball and
spring which allows air displaced by the steam
generatedinthechambertopassintothereservoir.
Once steam starts to pass, the ball then lifts and
seals. A small ‘bleed’ remains, however, and it is
quitenormalforsmallquantitiesofsteamtoescape
into the reservoir throughout the cycle.
❑Safety Valve (Fig. 2.3, item 16). The safety valve
isfittedonthechambertee-pieceattherearofthe
chamber,andisfactorysettoreleasepressurefrom
withinthechamber. Itisaprimarysafetydeviceand
must not be readjusted.
❑AirInSolenoidValve(Fig.2.3,item5). Theairinlet
valve controls the admission of bacteriologically
filteredairto thechamberduringthedryingphase.
Anon-returnvalvepreventsflowfromthechamber
to the bacterial filter to keep it dry.
❑Vacuum Solenoid Valve (Fig. 2.3, item 1). When
open,thisvalveallowsthevacuumpumptosuckair
and steam from the chamber.
