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4.14
Process control _________________________________________________________
The autoclave offers the following possibilities for
controlling a safe sterilization/disinfection process:
Successful conclusion of a process
As soon as a sterilization/disinfection is completed
successfully, i.e. keeping the required parameters
for pressure and temperature in the prescribed time,
the lamp
„
END“ lights and an acoustic signal can be
heard. If the protocol printer is connected, the
successful end of the cycle will be documented on
the printout.
Pressure-temperature correlation
During process, the correlation of temperature with
pressure can be controlled by observing the
thermometer (6) and the pressure gauge (5),
according to the curve for saturated steam (e.g. 2-
2.1 bar with 134-135°C). The precision of the
indicator instruments must be taken into account
here: see Section 5.2.
Electronic monitoring of parameters
During running of the program, the following
parameters will be automatically monitored under
microprocessor control:
Heat-up time
The maximum heat-up time is normally 3 minutes.
If overloading, insufficient venting, or fault in
operation prevent the autoclave from achieving the
values required by the selected program for
pressure and temperature within 5 min., then the
program will interrupt owing to time overrun, and the
lamps for
„
FAULT“ (10) and
„
RUNNING“ (12) will
flash.
Sterilization/disinfection time
During sterilization/disinfection process, the
parameters pressure and temperature are
constantly controlled. The sterilization/disinfection
time of 4 / 6 minutes will only run if both parameters
reach the required values (lamp "RUNNING" lights).
If the autoclave exceeds the monitoring time of
5.5 minutes
for
sterilization / 7.5 minutes
for
disinfection due to faulty run, the program will also
be stopped because of exceeding time. The lamps
for
„
FAULT“ (10) and
„
RUNNING“ (12) will flash in
this case.
Exceeding steam temperature
If the autoclave exceeds the steam temperature of
140°C during sterilization or 112°C during
disinfection due to a fault, the program will also
interrupt in such case, and the lamp for
„
FAULT“
(10) will glow. The lamps for
„
READY“ (11) and
„
RUNNING“ (12) will flash.
Temperature limitation
The automatic temperature limitation has already
been described (See Section 4.13).
4.15
Sterilizing frequency _____________________________________________________
Because of its parameters control system and its
optimised heating, the MELAG-autoclave
MELAquick
®
12
can be used for
sterilization / disinfection without interruption.
So 8-10 sterilizations per hour are possible.
5
Further informations about sterilization ________________________________
5.1
Total operating time ______________________________________________________
Operating time
"The operating time is the time needed for
sterilization without taking account of loading and
emptying." (DIN 58900)
Due to the parameter regulation of the autoclave,
the operating time is optimised mainly depending on
the number of items to be sterilized and the
temperature of the apparatus. The minimum
operating time (small load, immediate sterilization
before) needed for sterilization is about 5.5 minutes
and about 7.5 minutes for disinfection. The
maximum time (maximum load, first process after
complete pre-heat) is about 8
minutes for
sterilization and 9 minutes for disinfection.
Included times
The operating time includes times for pressure
generation, ventilation and heat-up of instruments
and chamber as well as for sterilization which
consists of equalization time, killing time and an
extra charge for safety.
5.2
Accuracy of process regulation ____________________________________________
The analogue instruments for pressure and
temperature of the MELAquick
®
12
work completely
independently from the microprocessor regulation
and are only for additional information about the run
state of the autoclave.
Because of their small size, the accuracy of these
instruments is only
±
0,1 bar (pressure gauge) and
±
2°C (thermometer).
Owing to the time delay of the temperature sensor, it
can happen that the indication of the temperature
reaches the correct value only after beginning of the
sterilization or disinfection time: i.e., while the lamp
„
RUNNING“ (12) is glowing, and after the required
temperature has already been reaches in the
chamber.
It may also happen during continuous operation, as
a result of constant high temperature of the
autoclave, that the temperature indicates on the
thermometer is 2°C higher than the temperature
shown for the first sterilization or disinfection cycle.
In the actual sterilization compartment, however,
there will be no temperature deviation.
Microprocessor control
The electronic control system, on the other hand,
operates with an absolute precision of 0.5°C and
controls the sterilization or disinfection temperature
with a maximum deviation of
±
0.3°C.
The microprocessor regulation in combination with
