- Control air dryer usually take the form of a refrigeration system to drop the temperature of the air below its dew point .
- The water droplets will collect on the surface of the fridge evaporator where they are led to an automatic drain.
- Further removal of water from the chilled air is effected by making the air swirl through a separating chamber where the water droplets collect on the outter surfaces.
- In some cases finallybthe air air can be led through dryers containing silica gel or activated alumina which will remove any remaining moisture from the air .
- This form of dryer must be fitted with means of refrigeration.
Any opening in a pressure vessel is kept to a minimum and for a man entry an elliptical hole is lesser in size than the corresponding circular hole. More over it is prime concern to have a smoothed generous radius at the corners to eliminate stress concentration. Hence other geometrical shapes like rectangle and square are ruled out. To compensate for the loss of material in the shell due to opening, a doubler ring has to be provided around the opening. The thickness of the ring depends on the axis length along the dirrection in which the stresses are maximum and the thickness of the shell. It is important to align the minor axis along the length of the vessel, as the stress in this direction is maximum. Longitudinal stress: Pd/2t where P= pressure inside the vessel, d= diameter of the arc, t= thickness of the shell plating Circumferential stress: Pd/4t More over a considerable material and weight saving is achieved as minor is along the direction of maximum stress.