INTRODUCTION -
11
undesired flow through the valves in case of power failure. A fail safe
function is achieved.
Pressure vessels
The sterilizer chamber jacket and steam generator are pressure vessels,
designed and built in accordance with standards laid down by official
bodies charged with monitoring this area of safety.
The internal steam supply to the sterilizer is protected against excessive
supply pressure by a safety on the steam generator, the sterilizer or both.
The connected supply lines from external steam, water or compressed
air networks must be protected against excessive pressure by safety
valves. The sterilizer supplier is not responsible for these valves. Per-
mitted supply media pressures are stated in “Utility data”.
Safety valves
Safety valves limit the system pressure, providing the last line of pro-
tection to prevent the design pressure of the vessel from being exceeded.
Safety valves are required to be inspected at prescribed intervals.
Monitoring the pressure behind the door seal
All valves admitting any medium to the chamber are kept closed until
the pressure behind the door seal is high enough to guarantee the tight-
ness of the chamber.
Built-in electrical steam generator
The sterilizer also has a fully-automatic built-in steam generator, with
tubular electric elements as the heat source.
Operation
The heating power is divided among a number of groups of elements.
The elements are controlled by a pressure switch with double changeo-
ver contacts, one for each heater element circuit. One group of contacts
limits the operating pressure of the steam generator. The other controls
reconnection of the power when the minimum pressure is reached.
Pressures higher than those stated on the electrical diagram should not
be set, since the steam will be superheated when admitted to the steri-
lizer chamber. On the other hand, if the operating pressure is allowed to
fall too far, the steam tends to become wet, which is undesirable for ster-
ilisation purposes.
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