may be present and checking vessels and other enclosed areas for adequate levels of oxygen and ensure absence of toxic or explosive gases. Any machines that are going to be worked on must be electrically disconnected, usually through the motor starter, so that it cannot operate. It is common practice to put a padlock on the motor starter, which can only be unlocked by the person or persons who is or are endangered by performing the work. Other disconnect means include removing couplings between the motor and the equipment or by using mechanical means to keep the equipment from moving. Valves on pipes connected to vessels that workers will enter are chained and locked closed, unless some other means is taken to insure that nothing will come through the pipes. Continuous processor (equipment) Continuous Production can be supplemented using a Continuous Processor. Continuous Processors are designed to mix viscous products on a continuous basis by utilizing a combination of mixing and conveying action. The Paddles within the mixing chamber (barrel) are mounted on two co-rotating shafts that are responsible for mixing the material. The barrels and paddles are contoured in such a way that the paddles create a self-wiping action between themselves minimizing buildup of product except for the normal operating clearances of the moving parts. Barrels may also be heated or cooled to optimize the mixing cycle. Unlike an extruder, the Continuous Processor void volume mixing area is consistent the entire length of the barrel ensuring better mixing and little to no pressure build up. The Continuous Processor works by metering powders, granules, liquids, etc. into the mixing chamber of the machine. Several variables allow the Continuous Processor to be versatile for a wide variety of mixing operations: Barrel Temperature Agitator speed Fed rate, accuracy of feed Retention time (function of feed rate and volume of product within mixing chamber) Continuous Processors are used in the following processes: Compounding Mixing Kneading Shearing Crystallizing Encapsulating Packing The Continuous Processor has an unlimited material mixing capabilities but, it has proven its ability to mix: Plastics Adhesives Pigments Composites Candy Gum Paste Toners Peanut Butter Spaghetti/Macaroni Waste Products References Sources and further reading R H Perry, C H Chilton, D W Green (Ed), Perry's Chemical Engineers' Handbook (7th Ed), McGraw-Hill (1997), Major industries typically each have one or more trade magazines that constantly feature articles about plant operations, new equipment and processes