Radiography in Modern Industry - Kodak

Sometimes the temperature of the cold water supply may be higher than required by theprocessor. In this situation, it is necessary to cool the water before piping it to the processor.This is the basic pattern of the water system of automated processors; the details of the systemmay vary slightly, however.Recirculation SystemsRecirculation of the fixer and developer solutions performs the triple functions of uniformly mixingthe processing and replenisher solution, maintaining them at constant temperatures, and keepingthoroughly mixed and agitated solutions in contact with the film.The solutions are pumped from the processor tanks, passed through devices to regulatetemperature, and returned to the tanks under pressure. This pressure forces the solutions upwardand downward, inside, and around the transport system assemblies. As a result of the vigorousflow in the processing tanks, the solutions are thoroughly mixed and agitated and the filmsmoving through the tanks are constantly bathed in fresh solutions.Replenishment SystemsAccurate replenishment of the developer and fixer solutions is even more important in automatedprocessing than in manual processing. In both techniques, accurate replenishment is essential toproper processing of the film and to long life of the processing solutions; but, if the solutions arenot properly replenished in an automated processor, the film may swell too much and becomeslippery, with the result that it might get stuck in the processor.When a film is fed into the processor, pumps are activated, which pump replenisher from storagetanks to the processing tanks. As soon as the film has passed the entrance assembly, the pumpsstop--replenisher is added only during the time required for a sheet of film to pass through theentrance assembly. The amount of replenisher added is thus related to the size of the sheet offilm. The newly added replenisher is blended with the processor solutions by the recirculationpumps. Excess processing solutions flow over a weir at the top of the tanks into the drain.Different types of x-ray films require different quantities of processing chemicals. It is, therefore,important that the solutions be replenished at the rate proper for the type or types of film beingprocessed and the average density of the radiographs.Replenishment rates must be measured accurately and checked periodically. Overreplenishmentof the developer is likely to result in lower contrast; slight underreplenishment results in gain ofspeed and contrast, but severe underreplenishment results in a loss of both. Severeunderreplenishment of developer can cause not only loss of density and contrast but also failureof the film to transport at any point in the transport system. Overreplenishment of the fixer doesnot affect good operation, but is wasteful. However, underreplenishment results in poor fixation,insufficient hardening, inadequate washing, and possible failure of the film to be transported inthe fixer rack or at any point beyond.Dryer SystemRapid drying of the processed radiograph depends on proper conditioning of the film in theprocessing solutions, effective removal of surface moisture by the squeegee rollers, and a goodsupply of warm air striking both surfaces of the radiograph.Heated air is supplied to the dryer section by a blower. Part of the air is recirculated; the rest isvented to prevent buildup of excessive humidity in the dryer. Fresh air is drawn into the system toreplace that which is vented.Radiography in Modern Industry 116