The actual sterilization time of e.g. 15 to 20 minutes at 121 °C
is only a fraction of the total time involved for an autoclave
procedure. Especially in the case of sterilizing liquids, the heating
up and cooling down phases are considerably longer.
The conventional procedure
In previously used conventional systems, even if the intended
sterilization temperature has been reached within the autoclave,
the liquids to be sterilized are often only at about 100 °C; the
temperature equilibrium time between chamber and liquids
normally takes much longer.
Up to 50 % shorter heat-up times as standard
Due to the combined temperature and pressure regulation, the
chamber pressure is increased during the heat-up phase. The
result: more rapid temperature equilibrium in the liquids and
a shorter heat-up time.
The cooling process for liquids is also very slow; this is because,
without active rapid cooling, the heat can only be reduced to
below 100°C by dissipating the heat via the chamber insulation
by radiation (see diagram: conventional cooling).
New system- and process technology now make it possible to
substantially reduce the overall time required for the sterilization
process. This means that several hours of time can be saved! It
also means that the media is not exposed to heat unnecessarily
long time (see diagram: rapid cooling).
Systec offers many functions for its autoclaves guaranteeing safe
liquid sterilization processes at higher productivity. Many of these
functions are standard or available as options depending on the
model range selected.
Standard functions in all models
- Temperature- and pressure-dependent door locking in line
with international standards and regulations.
- Redundant process control; temperature and pressure are
continuously monitored and controlled during the entire
- Rapid heat-up via optimized heat transfer to the liquid media.
- Flexible PT-100 temperature sensor for temperature measurement
in a reference vessel:
- Guarantees attainment of the desired sterilization temperature
in the liquid media.
- Guarantees cooling of the liquid media to a temperature
that is safe for removal.
Systec supplies autoclaves guaranteeing precise sterilization
processes, safe handling and increased productivity. Numerous
cooling functions are available for liquid sterilization.
Various optional rapid cooling systems enable the cooling times
for liquids to be significantly reduced. This conserves culture
media and makes for efficient utilization of the autoclave.
In addition to conventional cooling by regulated steam exhaust
down to 100 °C and subsequent very slow self-cooling down to
80 °C, optional cooling systems for rapid cooling are available.
- Cooling with ambient air ventilation.
- Mantle cooling with cooling water.
- Mantle cooling with cooling water and support pressure.
- Radial ventilator for air circulation and accelerated heat
removal from the chamber.
- Spray cooling with recirculated and recooled sterile water
and support pressure.
Conventional cooling/Rapid cooling
Water cooling with support pressure
Permanently under control
During the entire sterilization process, a flexible PT-100 temperature
sensor monitors the water temperature in a reference vessel. It is
thus guaranteed that the sterilization period begins only once the
sterilization temperature has been attained in the liquid to be
The cooling temperature is also constantly monitored. In accordance
with relevant standards, to prevent delayed boiling, the lid
can only be opened once the temperature of the liquid has been
reduced to at least 80 °C.
The use of support pressure in the form of sterile-filtered compressed
air during the cooling phase reliably prevents the culture
medium from boiling.
- No loss of liquid due to boiling of the culture media.
- Improved productivity from reduced cycle times and the
full utilization of the filling volume in each bottle.
- Prevention of delayed and over-boiling.
- Prevention of the risk of bottles bursting during or after
- Prevention of re-contamination by the use of hermetically
sealed bottles during sterilization.
- Reduction of cooling time by up to 60 %.
Water cooling with support pressure
Together with water cooling with support pressure, the ventilator
ensures accelerated removal of heat from the sterilization items
to the cooled chamber mantle. The ventilator is located in the lid
of the chamber (no reduction of chamber depth!) and is driven by
a magnetic motor fitted outside under the cover.
- Ventilation performance 250 m³/h.
- Reduction of cooling time by up to 70 %.
In conjunction with optional water cooling system with support
pressure and Radial Ventilator Systec succeeded to reduce again
the cooling time and hence the overall sterilization time considerably
through integration of an additional heat exchanger.
- Reduction of cooling time by up to 90 %.
- Depending on the load, cooling times between 15 and
60 minutes can be achieved.