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Air removal
If the autoclave does not have the Vacuum option fitted, the display will show “Steam Purge”,
which is the stage when air is removed from the chamber. The water in the bottom of the
chamber is heated to produce steam, which escapes through a valve at the rear of the
machine, carrying the air in the chamber with it.
For loads that are more likely to trap air, such as plastic discard, a vacuum system is
recommended. The stages displayed in this case are “Pre-Vacuum” and “Negative Pulsing”
(as explained above for the Vacuum System option). The vacuum has superior air removal,
but may increase the overall length of the cycle.
Heating up
The autoclave raises its pressure and temperature to the set sterilizing values specified for
the cycle. The time taken by this stage depends on the level of the set points and the
contents of the load to be sterilized. The load probe should be placed either in the load to be
sterilized or in a simulated load device. The stage will be complete when the sterilizing
temperature has been reached.
Sterilizing
During this stage, the cycle achieves its objective. Whilst the sterilizing temperature can be
set for any given cycle at any value between 105
0
C and 136
0
C, the values most commonly
chosen are 121
0
C or 134
0
C, depending on the nature of load to be sterilized (see below). If
the printer is fitted, its output during this stage will provide proof that the load has been
sterilized. The length of time for sterilization can also be selected by the user, up to a
maximum of 30 minutes.
Cooling
The final stage is “Cooling”. The cooling fan blows air over the chamber until the temperature
has been reduced to the desired level (usually 80
o
C). Three types of cooling are available on
Touchclave-R models:
• Normal cooling allows the steam pressure to drop gradually until it reaches
atmospheric pressure, relying on fans to perform the cooling action.
• Dynamic cooling works in a similar manner until the pressure has dropped to
1150mba, when the machine blows air through the chamber, thus speeding up the
cooling action and helping to dry the load.
• Ballast cooling maintains the chamber pressure during cooling by replacing the steam
with air. This method minimises the fluid loss and is recommended for media loads.
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