Almost all eye injuries are preventable by the use of appropriate control measures and suitable eye protectors. Research in the 1980s showed that the main reason why eye protectors are not worn, or are removed in hazardous areas, is due to their fogging during use. Resistance to fogging was also shown to depend on the design of the complete eye protector, and not just the surface properties of the lens.
This project aimed to develop an objective test for the resistance to fogging of different designs of complete eye protectors, for submission to CEN as a standard method. This would help manufacturers to develop improved designs, and inform users in their selection of suitable protectors.
The principle of the method has been agreed, but some refinement of the detail is needed before it can be submitted to CEN. The method is capable of classifying eye protector fogging resistance into up to four categories. The results have been shown to correlate well with the actual performance achieved when worn by human subjects.
Work on refining the method is continuing through a further series of inter-laboratory trials using standardised circuitry in the detection system.
The work consisted of three tasks:
a) identification by the co-ordinator's laboratory of a suitable candidate fogging detection method;
b) duplication of the test equipment by the other five partners in the project;
c) inter-laboratory trials of the method to establish its repeatability and reproducibility. In the test, fogging is induced by mounting the eye protectors on a moist, temperature controlled headform. Detection of condensation on the lenses is achieved using a miniature TV camera mounted in one eye socket of the headform. The TV camera observes a target, and the quality of the image is assessed by a simple processing technique. If fogging affects the visibility through the lens, the reduction in quality of the definition and contrast in the image of the target is detected.
These tasks have been completed, although the inter-laboratory trials revealed a number of areas where the method was not sufficiently closely defined.
Funding SchemeCSC - Cost-sharing contracts
RH1 2PA Redhill