(2) Heating unit. In the laboratory, the hot water tap may be utilized. In the
field, a suitable immersion-heating unit can readily raise the temperature of the solution
above 60F, the minimum processing temperature.
(3) Thermometer. Processing of radiographs requires that an accurate check
on the temperature of the solutions be maintained at all times by the use of a reliable
thermometer. The temperature should always be checked when the work is first begun
and at intervals throughout the day. The optimum temperature of 68F, recommended by
the American Standards Association, has been adopted. Do not attempt to judge the
temperature of a solution by dipping a finger into it.
(4) Tank insulation. The master tank may require insulation, especially when
there are wide differences between ambient air temperature and the optimum processing
temperature. If the air is much warmer than the processing solutions, an uninsulated tank
might condense enough moisture to be annoying and it could be difficult to hold the
solutions at the right temperature. Air conditioning solves this problem very effectively. In
the field, however, the specialist may find it necessary to improvise insulation with
g. Drainage Facilities. The drain line must be large enough to accommodate the
maximum simultaneous flow of water from both the water jacket and the washing tank.
Both size and pitch (slope) of the line affect the rate of flow. The pipe should be at least
two inches in diameter and the pitch at 1/4 inch per foot. Flushing the drain with rapidly
flowing water after old processing solutions have been discarded through it will help
prevent corrosion and deposits. In the field, drainage should be into a seepage pit or
MAINTENANCE OF TANKS
Trays, tanks, and other processing equipment frequently become discolored and
encrusted through use. Frequent rinsing and drying is the best prevention for these
conditions. Strong cleaners should be used only when really needed. Exercise care when
using these cleaners, because they usually possess strong acids or alkalines.
a. Oxidized developer stains (brown or yellow-brown) can often be removed with
soap and water. If not, tray cleaner formula or some similar product will be needed. An
effective tray cleaner can be prepared by mixing 32 ounces of water, three ounces of
potassium bichromate, and three ounces of concentrated sulfuric acid.
CAUTION: Always add the sulfuric acid to the water and potassium chromate solution,
stirring constantly. Never add the solution to the acid as it may cause boiling
and spattering, leading to serious burns.
To use, pour a small amount of the solution into the vessel, rinse it around to be sure it
reaches all surfaces, pour it out, and wash the vessel six to eight times with water. Do not
use the solution on your hands.
b. Developer tanks accumulate a scale of basic calcium sulfite, which is difficult to
scrub off. This scale is soluble in acids, but ease of removal varies according to the