but other materials can be used the inlet 62 is in communication with a source of water or other fluid and the fluid source can be a hot water heater for example preferably the hot water heater is a dedicated unit for the heat exchanger 38 in a closed loop configuration with the heat exchanger 38 other types of heat exchangers can be used with the present invention and be positioned at any point in the milk flow path a temperature sensor 44 is used to determine milk temperature throughout the pasteurizing process preferably the temperature sensor 44 is a precision fahrenheit temperature sensor model lm34 available from national semiconductor if the pasteurization process has been completed and the desired milk temperature has not been reached milk will continue to be circulated until the desired temperature is reached further the controller 22 is preferably in communication with a milk quantity sensor 43 which is preferably an integrated silicon pressure sensor mpx5010gp case 867b 04 available from freescale semiconductor www freescale com that uses a long stand tube 42 that traps air when the liquid level of the vat 34 increases as the milk level in the vat 34 rises pressure in the long stand tube 42 increases the milk quantity sensor 43 generates a voltage readout signal that is communicated to the controller 22 to automatically determine run time for any batch size of milk preferably.