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Review of Film System Technology - State of the ArtBart J.L.H. Vaessen
Business Group NDT Agfa Gevaert NV Mortsel, Belgium
The film system classification standard EN 584 part 1 and 2 form an integral part for certification and verification of film system performance at the user level. The tools needed for the verification according to EN 584 part 2 are:
The major part of the presentation will be devoted to the latest development in film system technology rendering ecological improvements and faster processing. The remainder of this written paper will extensively explain and document this exiting new development in today's film radiography technology.
Environmental policy varies greatly from country to country and region to region,
and furthermore is sometimes very unclear. Local authorities may impose stricter regulations.
The present German directive (Anhang 53) relating to industrial radiography lays down the maximum amount of silver freight in the rinsing water of a processor to 50 mg Ag/m2 processed film for film consumption between 3000 and 30.000 m2 year. Agfa has taken this German directive of silver freight of 50 mg Ag/m2 as target, since:
The freight (mg/m2) of Ag in the wash water is determined mainly by the silver concentration in the fixer (g/l).
The average silver concentration in the fixer of a correctly functioning processor is about 6 g silver per litre of fixer (with a fixer replenishment rate of 1,200 ml/m²).
This average concentration leads to a silver freight in the waste water of 300 mg/m², equivalent to around 20 ppm Ag (at 13l/m² water replenishment). In other words, high above our target norm.
In order to reduce the silver freight, the solution must be sought in a drastic reduction in the silver content of the fixer bath, e.g. electrolytic desilvering or cascade fixing.
Accordingly, Agfa has developed an approach for complying with ecological legislation in a step by step process. One of the first steps was the introduction of the Structurix Silverfix, which considerably reduces the concentration of silver in the fixer through closed loop electrolytic desilvering.
Secondly, a totally new processor is launched on the market: the Structurix NDT S eco, a film processor with fixer cascade system.
Now the total new eco Film System is presented with a new processor, new chemicals and optimised films: the Structurix eco Film System.
The Structurix NDT S eco, installed in the 5 minute cycle, forms the basis for the "Structurix eco Film System" in which the Structurix film, chemistry and processor are all carefully matched and tailored to ensure the best possible ecological results in terms of silver in the waste water.
The Structurix eco Film System:ecology goes hand-in-hand with economy
NDT S eco (5' cycle) + eco chemicals + Structurix films D2 to D7
|cubic grane structure|
a two-part bath, non-hardening developer for universal use but specially designed for super fast processing, with the lowest possible replenishment rates whilst maintaining its optimum developing capabilities.
one-part bath, non-hardening fixer, specially designed for super fast processing, with the lowest possible replenishment rates whilst rendering even improved fixing, and more important, archiving capabilities. Also usable for silver recovery by electrolysis
The film is then 100% fixed in the first fixer tank and then rinsed once more in the second fixer tank. Since fixer replenishment is carried out in the second fixer tank, the concentration of silver in this tank remains very low. There is therefor very little carrier-over of silver into the final water wash tank, so that the wastewater complies with most stringent standards.
Fixer replenishment works on the counterflow principle, with the first fixer tank being replenished from the overflow of the second fixer tank. An added advantage of this is that nearly all the silver released in the fixing stage ends up in the overflow from the first fixing tank. This does ensure maximum amount of silver in the used fixer, which does allow maximum recovery.
This unique film processing system ensures that the amount of silver in the wastewater from the Structurix NDT S eco processor is 15 to 25 times lower than in a conventional processing system.
Moreover the NDT S eco significantly reduces the amount of replenishment, not only of developer and fixer, but also of the water. This is achieved through accurate square meter replenishment.
In the Structurix eco Film System, the Structurix NDT S eco is set to the 5-minute cycle, processing at no less than 51 cm of film per minute, increasing capacity compared to the 8 min. cycle with 60%!
With the NDT S eco, ecology goes hand-in-hand with economy.
ecoDEV developer immersion time at 5 min. cycle in NDT S eco processor is 62.5 sec. Temperature for classified system is set at 31°C.
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