Oil Inlets & Outlets for Fryers
VOL. 20 NO. 5
Over a year ago, design work was started on improved oil inlets and outlets for Gem fryers. The configuration, controlling oil flow into and out of the fryer kettle, has a large influence on oil flow in the fryer. For many fryer applications, satisfactory oil flow is critical to meeting finished product specifications. For some products, oil velocity needs to essentially match belt speed. Too much turbulence will cause some battered product and formed product to stick together and leave the fryer in clumps, often called marriages. While most purchasers support marriage between a man and a woman, they do not want their pieces of fried product stuck together. Fryers with outside belt returns (a must if system oil capacity is to be held to a minimum) have to be correct to obtain satisfactory oil flow. Sweep oil inlets, often used to assure a smooth transition from the supply pipe to the fryer kettle, require too much oil volume.
Oil entering a Gem Equipment fryer passes through two perforated plates, reducing oil velocity and spreading the flow across the width of the fryer. Oil velocity in the pipe feeding an oil inlet ranges from six to sixteen feet per second depending on belt speed. Oil velocity is cut in half when the flow is split to cross pipes. The oil enters the inlet assembly at two points equal distant from each side to the center of the fryer. The oil inlet is two chambers. On the old design the first chamber was a pipe, with holes machined to feed oil into the second chamber. These holes had to be machined prior to welding the pipe into the kettle weldment. Oil flows through the holes machined in this pipe into the second inlet chamber. From the second chamber, oil enters the kettle through a perforated plate, which bolts to the fryer kettle. Since the inlet assembly is designed to minimize oil volume, selection of hole size and pattern is critical to proper oil flow in the fryer. That is why perforated plates, which are also used at the oil outlets, bolt to the kettle. Three years ago, almost half of the oil inlet perforated plates had to be redesigned and replaced to achieve satisfactory fryer oil flow. Progress has been made. Now, ninety percent of the time, perforated plates are now correct on the first try.
Design is critical, if satisfactory flows are to be obtained with low volume oil inlets and outlets. Equally important, the completed unit has to accurately match the design. For this reason on Gem fryers, all holes and slots that oil flows through, as well as surfaces for attaching perforated plates are machined. The new design replaces the perforated pipe with plate and allows oil inlet and outlet sections of kettle to be fabricated prior to machining. After fabrication, sections of kettle, up to 82 inches long and full width are machined in a large CNC machining center. In addition to eliminating a step in manufacturing, the new design reduces the dead space between the outlet and the next inlet from six to two and one half inches. On design as critical as fryer oil inlets and outlets, even with sophisticated computerized fluid flow profiling, testing is necessary with a new configuration. The new design was proven, with water, using an eight-foot wide section of fryer, with two inlets and two outlets, manufactured for this test. Last week, the new inlets and outlets passed their final test--operation in a customer's new fryer.