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Priorclave Manual 27125322-EN Issue 2
Automatic Timed Free-Steaming
What is free-steaming?
Incorporating a period of free-steaming into a cycle can improve air removal in difficult loads
and/or reduce temperature lag between the load and the autoclave, reducing process time at
higher temperatures. Free-steaming introduces a stage during heating up to Process
Temperature, when a solenoid valve at the rear of the autoclave is opened for a pre-set time.
The valve opens at a factory set temperature of just above 100
set as detailed below. During this time steam is being generated in the chamber in large
volumes and this creates turbulence as it passes through the load before escaping through the
valve. It is this turbulence that can assist with air removal.
Setting the free-steam time.
If free-steaming is required this is selected by pressing the free-steam button. The indicator
lights up to show that free-steaming is selected. The time display will now flash indicating that
the freesteam time, not the process time, is currently being displayed. The freesteam time can
now be set (in minutes) using the up/down buttons. If no further changes are made for a short
time the display stops flashing, and reverts to showing process time. If you wish to check the
freesteam time or make further changes then free-steaming should be deselected, then
reselected.
Caution should be used before setting a free-steam time longer than 15 minutes. Excessive
free-steaming times can use a large amount of water, increasing the possibility of the cycle
not completing due to a Low Water condition.
Free-steam temperature setting
Timed free-steaming will commence at a temperature slightly above 100
set at the time of manufacture. If required, this temperature may be increased by qualified
personnel and the turbulence caused by the escaping steam pressure can further assist with
air removal. It is desirable however to connect the autoclave to a drain and vent pipe (as
described Installation), as the release of pressurised steam into the laboratory should be
avoided.
Performance can be improved even further by fitting the optional pulsed free-steaming
system.
Pulsed Free-steaming
(Optional Function – included for autoclaves with vacuum cycles)
With certain loads and in certain situations the efficiency of the free-steaming process can be
improved by pulsing. When available according to program then free-steaming commences as
described above but at a higher temperature (usually about 112
for the entire free-steaming period the vent valve shuts off at a lower temperature (usually
o
about 107
C). The autoclave then heats up again to the temperature at which the vent valve
opens again. The autoclave will continue this cycle for the time set when selecting free-
steaming. This continual pulsing of steam out of the autoclave creates considerable
turbulence within the autoclave, helping to draw trapped air out of the load.
If fitted, this function is program specific and is usually set up during commissioning or by
request on particular programs in response to customer requests at the time of ordering.
When selected as part of the program the pulsing function replaces the standard free-steam
06/06/2012
o
C and is held open for the time
o
C, which has been
o
C). Instead of remaining open
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