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4.5.5 Exhaust
When the timed sterilization cycle is complete, the unit enters into the
exhaust stage, provided that a program other than the liquid program
was selected. The steam is exhausted from the chamber, bringing the
internal pressure down to atmospheric pressure.
Note:
In the Bio-Hazard cycles (optional for BH, bio-hazard models), all
exhausts from the chamber before completion of the Sterilization
phase are performed through the bio-hazard filter.
•
(PV, pre-vacuum models only) Drying: vacuum is built up and the air
pump is working.
4.6
Leakage Test - optional for PV (pre-vacuum) models
only
Vacuum is produced in the chamber down to P
1
=15 kPa. At this stage
all the valves close. The autoclave remains in this stage for 5
minutes. This period enables the condition in the chamber to reach
equilibrium. After the 5 minutes have elapsed the printer records the
pressure that is referred to as P
2
. At this point the test begins and
lasts 10 minutes. At the end of the test, the printer records the results.
The pressure at the end of the test is referred to as P
3
. The rate of
change of P
3
-P
2
shall not exceed 0.13 kPa/min.). If P
3
-P
2
exceed 0.13
kPa/min the printer will print “FAIL”. If P
3
-P
2
is within the required
value, the cycle will end normally.
Note:
During the test period the autoclave is not heated.
Operations Sequence
Vacuum is produced into the chamber down to 15-5 kPa.
The vacuum pump stops.
Note: During the test period the autoclave is not heated.
4.7
Bowie and Dick Test - optional for PV (pre-vacuum)
models only
After air-removal stage; vacuum pulses are performed. Then steam is
inserted into the chamber until the sterilization temperature is reached.
During sterilization phase; temperature and pressure are maintained
constant at the pre-set level 134ºC (273
º
F) for sterilization time 3.5
minutes. Then, steam is exhausted out of the chamber at a fast rate
until pressure decreases to ambient pressure. Drying by heating of
chamber is followed by a vacuum break (air inlet) to remove leftover
moisture from the instruments and wraps.
If the B&D test cycle failed, the screen color is changed from purple to
yellow
If the B&D test cycle ended successfully "Test Ended" message will
display and the screen color will remain purple.
