Radiography in Modern Industry - Kodak

Figure 77: The roller transport system is the backbone of an automated processor. Thearrangement and number of its components vary, but the basic plan is virtually the same.In most automated processors now in use, the film is transported by a system of rollers driven bya constant speed motor. The rollers are arranged in a number of assemblies--entrance rollerassembly, racks, turnarounds (which reverse direction of film travel within a tank), crossovers(which transfer films from one tank to another), and a squeegee assembly (which removessurface water after the washing cycle). The number and specific design of the assemblies mayvary from one model of processor to another, but the basic design is the same.It is important to realize that the film travels at a constant speed in a processor, but that the speedin one model may differ from that in another. Processing cycles--the time interval from theinsertion of an unprocessed film to the delivery of a dry radiograph--in general range downwardfrom 15 minutes. Because one stage of the cycle may have to be longer than another, the racksmay vary in size--the longer the assembly, the longer the film takes to pass through a particularstage of processing.Although the primary function of the transport system is to move the film through the processor ina precisely controlled time, the system performs two other functions of importance to the rapidproduction of high-quality radiographs. First, the rollers produce vigorous uniform agitation of thesolutions at the surfaces of the film, contributing significantly to the uniformity of processing.Second, the top wet rollers in the racks and the rollers in the crossover assemblies effectivelyremove the solutions from the surfaces of the film, reducing the amount of solution carried overfrom one tank to the next and thus prolonging the life of the fixer and increasing the efficiency ofwashing. Most of the wash water clinging to the surface of the film is removed by the squeegeerollers, making it possible to dry the processed film uniformly and rapidly, without blemishes.Water SystemThe water system of automated processors has two functions - to wash the films and to helpstabilize the temperature of the processing solutions. Hot and cold water are blended to theproper temperature and the tempered water then passes through a flow regulator which providesa constant rate of flow. Depending upon the processor, part or all of the water is used to helpcontrol the temperature of the developer. In some processors, the water also helps to regulate thetemperature of the fixer. The water then passes to the wash tank where it flows through and overthe wash rack. It then flows over a weir (dam) at the top of the tank and into the drain.Radiography in Modern Industry 115