55291 NDT BROCHURE.indd - NDT Equipment Services Ltd

PLASTIC CASSETTE INFORMATIONPlastic CassettesAll types of Single-Envelope Plastic Cassettes are of the same design. They consist of asingle envelope, open at one end, through which film and screens are loaded and unloaded. Theopen ends of the envelopes fold over, producing an effective light seal. They are then held closed bymeans of VELCRO’ nylon fastener.There is an extra finger-tab at the bottom to assist in holding the cassette to the bench foreasier and quicker unloading. Closure is normally made on the shorter side of a rectangular cassette,special versions, with the opening on the long side, can be made to order.STANDARD SINGLE ENVELOPE CASSETTES These are made from 400 micron black PVC andhave become, over the years, the standard cassette for industry. We do not recommend their use invery cold weather and advise great care in loading and unloading them in sub-zero temperatures.REINFORCED SINGLE ENVELOPE CASSETTES These are made from thin, yet strong PVC/Nylon/PVC laminated material. The nylon reinforcement is in the form of a mesh and reduces the tendencyof the PVC to split at the seams after much use. The PVC laminate retains its flexibility in cold climates.Reinforced cassettes are therefore more suitable for use at lowtemperatures than the Standard type.ONE SEAM SINGLE ENVELOPE CASSETTES These represent the first major advance in cassettedesign since the introduction of ‘VELCRO’ fastening. Constructed in rugged nylon-reinforced PVC,they are made to outlast any other type of flexible cassette. They areconstructed without side-seams, there is just one joint on the back of the cassette. This designovercomes the weakness of other single envelopes that are welded along the sides; there is notendency to split.The Cassettes are made from specially - formulated, heavy-duty, nylon-reinforced PVC. They areblack on the inside for light-tightness and yellow on the outside for easy recognition.HEAVY DUTY SINGLE ENVELOPE CASSETTES These are made from double-thickness materialconsisting of one layer of standard PVC and one layer of the nylon-reinforcedmaterial. This combination produces a cassette capable of withstanding very tough treatment atnormal temperatures.DOUBLE ENVELOPE CASSETTES These consist of two plain black envelopes without any means ofclosure. Film and screens are loaded into the inner envelope, the smaller of the two. This is theninserted, open end first, into the larger outer envelope. Light – tightness isassured due to the open end of the inner is up against the closed end of the outer. They are madefrom the standard 400 micron material and are clearly marked ‘INTEX BACK’ on both the inner and theouter envelope for easy identification in the darkroom and out on site.The main advantage of Double-Envelope Cassettes is that they lie perfectly flat, having nofold-over ends or ‘VELCRO’ fastening.Click here to return to contents page vPage 11