T.O. 33B-1-1
1-74
g. Expose equal sections of the radiographically exposed test film to the safelight by sliding the opaque
material the length of the film in 6 minute, 3 minute, 1 minute, 30 seconds, 15 seconds, 0 second time
intervals, (leaving the last section unexposed to the safelight). This will result in six test film sections,
each with a different safelight exposure consisting of the following: 10 minutes and 45 seconds, 4
minutes and 45 seconds, 1 minute and 45 seconds, 45 seconds, 15 seconds and 0 seconds.
h. Cover the entire test film with the opaque material, taking care not to lift the mask off of the test film,
as this would result in the 0 second section being exposed to the safelight.
i. Turn off the safelight being tested.
j. Develop the film as you would normally, with the exception of it being performed in total darkness.
k. Repeat the individual safelight test procedure for each safelight, if required. Great care must be taken
not to unintentionally expose test film to safelight. Undeveloped test film SHALL be maintained in a
light tight container prior to it being developed and not being used to perform a safelight test.
l. Upon completing the initial individual safelight test for each safelight, perform the collective safelight
test. The initial and periodic collective safelight test is similar to the individual safelight test with the
exception of the following:
(1)
All safelights SHALL be turned-on during the safelight time interval exposures.
(2)
The radiographically exposed test film SHALL, be positioned in the usual area where normal
undeveloped radiographically exposed film is handled. This area SHALL NOT be less than four
feet from any safelight source.
m. After all test films have been developed in total darkness, read the densities of the five safelight exposed
sections comparing them to the sixth section on their respective test film. The section with the least
amount of safelight exposure that has a measurable density increase is the maximum time that an
undeveloped radiographic film SHALL be allowed to be exposed to safelight in the darkroom.
n. If this time restriction is 4 minutes and 45 seconds or less, or not suitable for operational needs, one or
more of the following actions SHALL be taken:
(1)
Replace safelight filters that are faded, cracked, are not designated for industrial radiographic
film, crazed, do not fit properly, or scratched.
(2)
Replace safelight bulbs that exceed the wattage recommended by the manufacturer.
(3)
Replace safelights that are unserviceable, such as emitting ambient light.
(4)
Eliminate or reconfigure uncontrollable ambient light sources such as doorways, ventilating and
heating ducts/vents, faulty film pass through box, building structural cracks, and holes around
pipes and electrical wiring.
(5) In the event that the individual safelight tests are all within an acceptable tolerance, but the
collective safelight test is unacceptable, investigate, the validity of the individual safelight test and
when, in fact, the results of these tests are correct, reduce the number of safelights in the darkroom.
The level of safelight that SHALL be present is the minimum required to perform undeveloped film
preparation/ development operations.
