- Size of specimen support: 125 mm diameter X 60 mm height
- Size of test specimen: 250 mm diameter
- Size of exposing chamber: 400 mm X 400 mm X 800 mm
- Size of developing chamber: 400 mm X 400 mm X 200 mm
- Standard: IS 8357-1977
The METLOR Drape Meter consists of a circular specimen support, an electric lamp to give off light, and an exposing and developing arrangement using light sensitive ammonia paper to determined the area covered by the shadow of the test specimen, and an electric lamp to expose the ammonia paper to determine the area covered by the shadow of the test specimen. The circular specimen support is made out cast aluminum and is fixed over a clear acrylic sheet. The sheet is hinged at one end and can be lifted for placing the ammonia paper for exposure. The paper is kept below the acrylic sheet on a resilient surface so that it is in close contact with the sheet when it is horizontal. The specimen holding and paper exposing arrangement are kept inside a sheet metal exposing chamber. The electric lamp is fitted at the upper end of the chamber so that light rays coming from it are intercepted by the test specimen. The rays which are not intercepted fall on the paper and expose it, thus giving a demarcation between exposed and unexposed areas. The chamber has a close fittings door. It has ventilation holes near its bottom and top for keeping it cool. An ammonia vapor developing chamber in which the exposed paper is kept for developing is provided below the exposing chamber. This chamber has a close fitting door and an arrangement to keep ammonium hydroxide to create a suitable atmosphere for developing the print. The test specimen is kept over a welded wire mesh platform to ensure a uniform developing. The outside of the apparatus is finished in dark admiralty gray synthetic enamel to give it a corrosion resistant finish. A metal template of 250 mm diameter have a central hole for marking and cutting the test specimens, a specimen pressing a disc, one hundred sheets of ammonia process paper, and one bottle of ammonium hydroxide are supplied as standard accessories.