Autoclaves utilise direct and indirect heating systems to achieve a uniform temperature inside the vessel. Indirect systems transfer heat via a heat exchanger and direct systems have the heat source within the autoclave and aims to maximize the transfer of heat from the elements to the pressure medium. Autoclaves are available with steam, electric, gas heating or thermal oil.
Pressure control is possible through pressurised and depressurised gradients and modulating values on the exhaust pipes and inlets. Autoclaves are pressurized with air up to 250 F and with nitrogen above 250F and assists in heat transfer.
Some autoclaves make use of dry saturated steam, whereby air is removed from both the load and the chamber itself. The most effective way is the vacuum system, where a vacuum is achieved prior to the introduction of steam. Once air is removed, temperature and pressure in the vessel rises until it reaches the required setting. The use of direct steam enables the process to be faster and hence more efficient.
Basic autoclaves will have water continuously topped up in the vessel until the correct temperature is reached through the heated elements and enables the chamber water to boil to produce steam. The addition of a integral steam generator removes the heating element and gives more control over steam production.
The use of direct steam and external steam generators that feed directly into the unit, are mainly used of sites who already have a steam supply or require larger autoclaves.
There are many different kinds of autoclave available on the market and JBC will advise on which is the most suitable, depending on the purpose of the autoclave and will ensure it is maintained throughout its life cycle.