The water is heated using live steam through a brazed plate heat exchanger or cooled using ethylene glycol solution through a brazed plate heat exchanger. Mains water is fed to the circulation pump, which then circulates water through the heat exchanges and to the jacket. Before use, any air must be purged from the circulation system so the pump does not rum dry and create a hot spot. After the autoclaving process, the cooling heat-exchanger is turned on, cooling the circulation water and thus reducing the time for cool down of the fermenter. During operation, cooling is required on the fermenter due to the exothermic metabolism of the microbes.
Heating is used to maintain temperature against ambient temperatures.
The PC controls 24 volt relays that operate the solenoid valves. Air volume control can be manual control for fungal and yeast work, due to the lower oxygen uptake requirements than that for bacterial work, whereby computer control is required. For sanitary purposes, valves to control flow of fermenter contents or materials entering the fermenter must use diaphragm valves. The number of these valves has been kept to a minimum for this purpose. All other valves may either be gate or needle valves made from brass, ie.