4-6
P129394-176
Operator Manual
Techniques of Sterilization
4.5 Vacuum Leak Test
The Vacuum Leak Test (see appropriate cycle description in
) measures the integrity of the
sealed pressure vessel and associated piping to assure air is not
being admitted to the sterilizer during the vacuum drawdowns.
After running a Leak Test cycle, a value or leak rate will be printed on
the printer tape. This value will help define a trend over a period of
time if the integrity of the system begins to deteriorate (i.e., allowing
air to enter the system). By running a Leak Test cycle daily or weekly,
the operator or maintenance personnel can always monitor the air
tightness of the system and make repairs or adjustments when
necessary.
NOTE:
A leak rate of greater than 1 mmHg per minute indicates a
problem with the sterilizer that must be addressed.
4.6 Recommendations
for the Sterilization
Process
Process all goods using prevacuum cycles.
The AMSCO C Series
small steam sterilizer is not a gravity displacement sterilizer. Run
gravity cycles only when qualified personnel have evaluated the
loads and determined the efficacy of a gravity cycle.
Saturated steam is a well controlled, reliable method for processing
items which can withstand the temperatures and pressures
associated with steam sterilization. The requirements for achieving
reproducible results are well known by many users, but are not
always understood.
The condition most likely to result in sterilization problems is a failure
to completely remove air from items being sterilized. For example,
placing an empty beaker or bowl in an upright position in a gravity
displacement sterilizer may result in the object not being sterilized,
or may require exceptionally long sterilization times. This problem is
caused by air trapped in the object; air has almost twice the density
of saturated steam under the same conditions. Thus, air remains in
the container’s bottom while steam forms a stable layer above it.
(Similar to oil forming a stable layer over water.) As long as there is
no mechanism for actively mixing air and steam, the bottom of the
container is only exposed to dry heat, which is not an effective
sterilization method at the time and temperatures typically used in
steam processes.
The best method for enhancing sterilization of solid-bottom
containers in gravity displacement cycles is to orient all objects in a
position which would allow water to flow out. When steam enters the
chamber, it tends to layer over trapped air. If, however, an object is
oriented so air is not trapped, but can flow out; air flows out to be
replaced by steam. Steam can now reach all surfaces and effect
sterilization.
WARNING – STERILITY
ASSURANCE HAZARD: Load
sterility may be compromised
if the biological indicator or
vacuum leak test indicates a
potential problem. If these
indicators show a potential
problem, refer the situation to
a qualified service technician
before using the sterilizer
further.
!
