For vessels which need to be heated or cooled, there are several types of heat transfer surfaces which can be applied to sidewall or bottom. The amount of heat transfer can be knowing the media temperature, starting and desired ending temperature, quantity and size of insulation, the type of product in the vessel, and the desired times. Typical heating/cooling medias which can be used in a vessel heat transfer jacket are: steam, hot and cold water, glycol, heat transfer oils, refrigerants, or any pumpable fluid. The heat transfer jacketing can be applied in distinct zones to permit the use of different heat transfer media, and to allow for variable batch sizes. The heat transfer jacket may need to be ASME certified like a vessel, especially for steam service over 15 psi. For liquid media, the lowest connection is typically the inlet and outlet the uppermost. This forces the entrained air out of the system. When liquid media is used, at least 7 gpm flow should be supplied to each jacket zone, however, higher flow rates may be necessary depending on your desired duty. For steam service, the steam is introduced into the uppermost connection, and the condensate pulled off of the bottom. The velocity of the steam supplied through the jacket depends on the type of jacketing selected.