Radiography in Modern Industry - Kodak

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Figure 71: Method of fastening film on a developing hanger. Bottom clips are fastenedfirst, followed by top clips.CleanlinessProcessing tanks should be scrubbed thoroughly and then well rinsed with fresh water beforefresh solutions are put into them. In warm weather especially, it is advisable to sterilize thedeveloper tanks occasionally. The growth of fungi can be minimized by filling the tank with anapproximately 0.1 percent solution of sodium hypochlorite (Clorox, "101," Sunny Sol bleaches,etc, diluted 1:30), allowing it to stand several hours or overnight, and then thoroughly rinsing thetank. During this procedure, rooms should be well ventilated to avoid corrosion of metalequipment and instruments by the small concentrations of chlorine in the air. Another method isto use a solution of sodium pentachlorphenate, such as Dowicide G fungicide, at a strength of 1part in 1,000 parts of water. This solution has the advantage that no volatile substance is presentand it will not corrode metals. In preparing the solution, avoid breathing the dust and getting it orthe solution on your skin or clothing or into your eyes.DevelopmentDeveloper SolutionsPrepared developers that are made ready for use by dissolving in water or by dilution with waterprovide a carefully compounded formula and uniformity of results. They are comparable inperformance and effective life, but the liquid form offers greater convenience in preparation,which may be extremely important in a busy laboratory. Powder chemicals are, however, moreeconomical to buy.When the exposed film is placed in the developer, the solution penetrates the emulsion andbegins to transform the exposed silver halide crystals to metallic silver. The longer thedevelopment is carried on, the more silver is formed and hence the denser the image becomes.The rate of development is affected by the temperature of the solution--as the temperature rises,the rate of development increases. Thus, when the developer temperature is low, the reaction isRadiography in Modern Industry 106
slow, and the development time recommended for the normal temperature would result inunderdevelopment. When the temperature is high, the reaction is fast, and the same time wouldresult in over development. Within certain limits, these changes in the rate of development can becompensated for by increasing or decreasing the time of development.The time-temperature system of development should be used in all radiographic work. In thissystem, the developer temperature is always kept within a small range and the time ofdevelopment is adjusted according to the temperature in such a way that the degree ofdevelopment remains the same. If this procedure is not carefully observed, the effects of even themost accurate exposure technique will be nullified. Films cannot withstand the effects of errorsresulting from guesswork in processing.In particular, "sight development" should not be used; that is, the development time for aradiograph should not be decided by examining the film under safelight illumination at intervalsduring the course of development. It is extremely difficult to judge from the appearance of adeveloped but unfixed radiograph what its appearance will be in the dried state. Even though thefinal radiograph so processed is apparently satisfactory, there is no assurance that developmentwas carried far enough to give the desired degree of film contrast. (See "Effect Of DevelopmentTime On Speed And Contrast".) Further, "sight development" can easily lead to a high level of fogcaused by excessive exposure to safelights during development.An advantage of standardized time-temperature processing is that by keeping the degree ofdevelopment constant a definite check on exposure time can always be made. This precludesmany errors that might otherwise occur in the production of radiographs. When the processingfactors are known to be correct but the radiographs lack density, underexposure can beassumed; when the radiographic image is too dense, overexposure is, indicated. The firstcondition can be corrected by increasing the exposure time; and the second, by decreasing it.The methods for calculating the required changes in exposure are given in Arithmatic ofExposure.Control of Temperature and TimeBecause the temperature of the processing solutions has a decided influence on their activity,careful control of this factor is very important. It should be a rule that the developer be stirred andthe temperature be checked immediately before films are immersed in it so that they can be left inthe solution for the proper length of time.Ideally, the temperature of the developer solution should be 68°F (20°C). A temperature below60°F (16°C) retards the action of the chemical and is likely to result in underdevelopment,whereas an excessively high temperature not only may destroy the photographic quality byproducing fog but also may soften the emulsion to the extent that it separates from the base.When, during extended periods, the tap water will not cool the solutions to recommendedtemperatures, the most effective procedure is to use mechanical refrigeration. Conversely,heating may be required in cold climates. Under no circumstances should ice be placed directly inprocessing solutions to reduce their temperature because, on melting, the water will dilute themand possibly cause contamination.Because of the direct relation between temperature and time, both are of equal importance in astandardized processing procedure. So, after the temperature of the developer solution has beendetermined, films should be left in the solution for the exact time that is required. Guessworkshould not be tolerated. Instead, when the films are placed in the solution, a timer should be setso that an alarm will sound at the end of the time.AgitationRadiography in Modern Industry 107
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RadiographyinModernIndustry
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RadiographyinModernIndustryFOURTH E
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ContentsIntroduction...............
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Chapter 1: The Radiographic Process
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Intensifying ScreensX-ray and other
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makes it a very suitable material f
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Figure 6: Typical voltage waveforms
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Table I - Typical X-ray Machines an
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The wavelengths (or energies of rad
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Table III - Industrial Gamma-Ray So
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1. The source of light should be sm
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B and H in the Figure 13 show the e
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Figure 14: Geometric construction f
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Figure 17: Pinhole pictures of the
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The kilovoltage applied to the x-ra
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Figure 21: Schematic diagram of som
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kind of material radiographed, the
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instance, the kilovoltage may be fi
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The technique need not be limited t
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Chapter 5: Radiographic ScreensWhen
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Contact between the film and the le
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Figure 29: The number of electrons
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lead foil screens ran be retained w
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Figure 33: The sharpness of the rad
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Figure 34: Low density (right) is a
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such as a wall or floor, on the fil
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from this source. Since scatter als
Page 55 and 56: A filter reduces excessive subject
Page 57 and 58: Definite rules as to filter thickne
Page 59 and 60: 0.010-inch front screen of value be
Page 61 and 62: Example: Suppose that with a given
Page 63 and 64: If the milliamperage remains consta
Page 65 and 66: espectively. In other words, a cons
Page 67 and 68: Any given exposure chart applies to
Page 69 and 70: Figure 46: Typical gamma-ray exposu
Page 71 and 72: where the slope of the characterist
Page 73 and 74: Figure 49: Characteristic curves of
Page 75 and 76: Figure 51: Characteristic curve of
Page 77 and 78: Nomogram MethodsIn Figure 54, the s
Page 79 and 80: Figure 56: Transparent overlay posi
Page 81 and 82: Figure 58: Overlay positioned so as
Page 83 and 84: The problem of radiographing a part
Page 85 and 86: Figure 62: System of lines drawn on
Page 87 and 88: Chapter 8: Radiographic Image Quali
Page 89 and 90: Film contrast refers to the slope (
Page 91 and 92: Hole Type PenetrametersThe common p
Page 93 and 94: of the same thickness as the specim
Page 95 and 96: Chapter 9: Industrial X-ray FilmsMo
Page 97 and 98: Figure 70 indicates the direction t
Page 99 and 100: the lead letters on a radiation-abs
Page 101 and 102: Therefore, protection requirements
Page 103 and 104: 5. Avoid pressure damage caused by
Page 105: Paddles or plunger-type agitators a
Page 109 and 110: ubbles make their way to the surfac
Page 111 and 112: When development is complete, the f
Page 113 and 114: soften considerably with prolonged
Page 115 and 116: Figure 77: The roller transport sys
Page 117 and 118: Rapid Access to Processed Radiograp
Page 119 and 120: Figure 78: Film-feeding procedures
Page 121 and 122: Chapter 11: Process ControlUsers of
Page 123 and 124: 3. Age of the developer replenisher
Page 125 and 126: Figure 80: Control chart below for
Page 127 and 128: DiscussionDensitometric data and pr
Page 129 and 130: Figure 82: Plan of a manual x-ray p
Page 131 and 132: Figure 83: A schematic diagram of a
Page 133 and 134: loading-bench activities are carrie
Page 135 and 136: KODAK Quinone-Thiosulfate Intensifi
Page 137 and 138: Methylene-Blue MethodTwo variations
Page 139 and 140: KODAK Hypo Test Solution HT-2Avoird
Page 141 and 142: In summary, use of the test papers
Page 143 and 144: narrow angle would be very thick, e
Page 145 and 146: When radiation passes through a spe
Page 147 and 148: Figure 89: Demonstration of the eff
Page 149 and 150: Figure 90: The amount of gamma radi
Page 151 and 152: The radiograph exposed in the right
Page 153 and 154: To illustrate, let us assume that t
Page 155 and 156: Figure 95: High-speed x-ray picture
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Figure 97: Two methods of neutron r
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Duplicating RadiographsSimultaneous
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Sometimes, as when sets of referenc
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PhotofluorographyIn photofluorograp
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discontinuities or of segregation i
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from the camera or by reaching down
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Figure 106: Schematic diagram of th
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valuable technique, for instance, i
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The position of the spots is determ
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Powder Diffraction File, Internatio
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Processing TechniquesRadiographs on
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Since this formula applies only to
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such that it does not distort the i
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Figure 113: A: Representation of a
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Figure 115: Characteristic curve of
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film fairly well. If high densities
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Density = 1.5 Density = 2.5Film Rel
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In most industrial radiography, the
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e noted here. Although the average
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Chapter 17: Film Graininess; Signal
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The ratio of signal to noise has a
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Chapter 18: The Photographic Latent
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Thus, the change that makes an expo
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Figure 130: Stages in the developme
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electrons by successive Compton int
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Development is essentially a chemic
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Chapter 19: ProtectionOne of the mo
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duct is brought into the x-ray room
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