Tuttnauer LabSci 11-V, Operation And Maintenance Manual

Page: 25 / 97

Page 24

Excess temperature protection.
3.17 Description of Operation
3.17.1 Heat
The vertical autoclaves are equipped with immersion type, heating
elements. After water has been introduced to the chamber and the unit
has been activated, the heating elements begin to heat. The
temperature and pressure in the chamber increase until appropriate
levels are reached. Sensors located inside the chamber control the
temperature and pressure levels.
3.17.2 Sterilization
The sterilization temperature is factory set at 134

C (273

F) for
instruments and at 121

C (250

F) for liquids and other materials for
which this temperature is appropriate. These settings may be modified
before each cycle. When sterilization temperature is reached, the timed
sterilization cycle begins.
3.17.3 Cooling
The autoclave is designed to operate two liquid cooling cycles, as
follows:
Sealed bottles (cooling with compressed air)
On completion of the sterilization stage, feed water starts flowing
through the cooling coil mounted around the outer side of the chamber.
Compressed air is injected inside the chamber and keeps a constant
air pressure to balance the internal pressure of the liquids inside the
bottles. Compressed air is passed through a 0.2µ microbiological filter.
When temperature of the liquids reaches the final set temperature, the
cooling stage is completed, flowing water and compressed air is
stopped, pressure in the chamber goes down to atmospheric pressure.
At this stage, the door of the autoclave can be opened, and the
sterilized materials can be taken out of the chamber.
Unsealed bottles (cooling without compressed air)
On completion of sterilization, steam is exhausted from the chamber at
a slow rate. When chamber pressure goes down to atmospheric
pressure, water starts flowing through the cooling coil mounted around
the outer side of the chamber. On conclusion of the cycle the water