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Priorclave Manual 27125322-EN Issue 2
06/06/2012
drainage services provided.
The point where connection from the autoclave to the drainage system is made should be
within 2 metres of the autoclave. The location of individual connections is shown on the
installation drawings.
Multiple autoclaves in a single location
If more than one autoclave is to be installed at a single location then the services described
need to be provided for each autoclave. If more than one autoclave is utilising the same drain
and/or vent arrangement, then there may be problems due to cross flow of effluent between
autoclaves. For example if one autoclave is being loaded by the operator whilst the other is in
the free-steaming stage, then it may be possible for hot air and steam being discharged by
one autoclave to enter the other presenting a hazard to the operator. If common services are
to be shared it is essential that these are sufficiently isolated from one another to prevent
cross flow.
Safety Valve
All autoclaves are fitted with an over pressure safety valve to protect the autoclave from over
pressurisation. This valve will emit large volumes of steam in the event of the autoclave
exceeding its maximum working pressure. It is a requirement during safety valve function, and
routine testing to be able to see and hear if the safety valve has operated.
It is Priorclave's preferred policy to direct the safety valve outlet to discharge to the floor at
the rear of the autoclave, however some establishments prefer safety valve outlets to be
piped to a high level outside the building.
If this is required the pipe-work for this should be provided, and terminated within 1 metre of
the safety valve discharge point at the rear of the autoclave. All safety valve pipe-work should
be DN25. A drainage point should be provided at the lowest point of the safety valve pipe-
work. This should be a pipe of approximately 6mm ID, and should be positioned to discharge
into a suitable receptacle to the rear of the autoclave. No valve should be fitted to this
drainage point thereby allowing it to act as a "tell tale" indicating if the safety valve is
operating.
Under no circumstances must any isolating valve be fitted to the safety valve pipe-work.
External pipe-work must be designed to be self draining, and under no circumstances should
water be able to collect in a trap, which could freeze in cold weather. See also BS3970 part 1
1990, sections 7.2.4 and 7.2.5.
Autoclaves with water tanks and drip trays
A separate drain is required for the connection of water tank and drip tray outlets. This may
be a common connection to the same drainage system as above, but in such cases a sufficient
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