Item 1: New Rolling Thin Film Oven (RTFO) The RTFO system must meet the following additional requirements: Oven—A double-walled electrically heated convection type with inside dimensions as follows: a height of 381 mm (15 in.), a width of 483 mm (19 in.), and a depth (with door closed) of 445 ± 13 mm (171 /2 ± 1 /2 in.). The door must contain a symmetrically located window with dimensions of 305- to 330- mm (12- to 13-in.) wide by 203- to 229-mm (8- to 9-in.) high. The window must contain two sheets of heat-resistant glass separated by an air space. The window should permit an unobstructed view of the interior of the oven. The heating element must be located below the oven floor and must be adequate to maintain the required temperature. The oven must be vented at the top and bottom. The bottom vents must be located symmetrically to supply incoming air around the heating elements. They must have an open area of 15.0 ± 0.7 cm2 (2.31 ± 0.11 in.2 ). The top vents must be symmetrically arranged in the upper part of the oven and have an open area of 9.3 ± 0.45 cm2 (1.45 ± 0.07 in.2 ). The oven must have an air plenum covering the side walls and ceiling, the air space being 38.1 ± 4.8 mm (11 /2 ± 3 /16 in.) deep from the walls and ceiling. At a midpoint in the width of the oven and 152 mm (6 in.) from the face of the circular metal carriage to its axis, a squirrel cage-type fan 133.4 mm (51 /4 in.) outside diameter by 73 mm (27 /8 in.) wide must be turned at 1725 r/min by an externally mounted motor. The squirrel cage fan must be set so that the fan turns in an opposite direction to its vanes. The air flow characteristics of the fan-plenum system must be suctioned from the floor of the oven through the wall plenums with the air exiting through the fan. The oven must be equipped with a proportional temperature controller capable of maintaining a temperature of 163 ± 1.0°C (325 ± 1.8°F). The sensing element of the controller may be placed at any location that enables the oven to maintain temperature control as specified in this standard. The temperature controller must be capable of bringing the fully loaded oven back to the test temperature within a 10-min period after insertion of the samples in a preheated oven. A thermometer must be hung from or affixed to a mounting in the ceiling, which is 51 mm (2 in.) from the right side of the oven at a midpoint in the depth of the oven so that the bulb of the thermometer or the tip of the sensor of the alternative thermometric device is within 25 mm (1 in.) of an imaginary line level to the shaft of the circular metal carriage. The oven must be provided with a 305-mm (12-in.) diameter vertical circular metal carriage. This carriage s must be provided with suitable openings and clips for firmly holding eight glass containers in a horizontal position. The vertical carriage must be mechanically driven through a 19-mm (3 /4-in.) diameter shaft at a speed of 15 ± 0.2 r/min. The oven must be equipped with an air jet positioned to blow heated air into each container at its lowest point of travel. The air jet must have an outlet orifice 1.02 mm (0.04 in.) in diameter (No. 60 drill) connected to a 7.6-m (25-ft) length of 7.9-mm (5 /16- in.) O.D. refrigeration copper tubing. This tubing must be coiled to lie flat on the bottom of the oven and lead to a source of fresh-dried, dust-free, regulated air. The tubing in the bottom of the oven must be exposed to the plenum of the oven and must not be covered by aluminum foil or other material
