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A Glossary of Filter Technology
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Absolute Filtration Rating: The diameter (in microns) of the largest glass bead which, under constant flow, just passes through the mesh. Calender: To smooth and reduce the thickness of wire cloth by passing it between heavy rollers to flatten the high points at wire intersections. Also known as "rolling." Crimp: Corrugation of the wires of woven wire cloth to lock them in place. "Double Crimp" crimps at the points of intersection in both warp and shute wires. "Intermediate Crimp" involves additional crimping between those at intersections of wires. Dutch Weave: Shute wires are inserted closely together, forming a dense pattern with wedge-shaped holes. Edges: Determined by the
weaving process: a roll of wire cloth will have either Fiber Metal Felt: Sintered,
non-woven stainless steel filter media with excellent Flux Rate: Pounds per hour per unit area of filter area. Gasket: A flat metal rim that matches the size and shape of the screens with which it will be used. The gasket prevents seepage of the melt being extruded. Gel: A soft, amorphous structure common in polyester and nylon melts; creates spinning problems such as breaks and slow holes. Market Grade: Wire cloth with a standard weave and standard wire diameter in each mesh; stocked for general-purpose work. Mesh: The number of openings in a linear inch, measured from the center of one wire to a point one inch distant. "Mesh" is another name for wire cloth. Micron Rating: The smallest
particle that can be removed by filter media. Oblong: Mesh Wire cloth with a greater number of wires (usually the shute wires) in one direction to produce rectangular openings. Opening: The space between adjacent parallel wires, usually expressed in decimal parts of an inch. Pack Pressure: Pressure generated inside the pack body by the metering pump. Total pack pressure is the sum of pressure generated by filter media, spinnerette, distribution plate, and inlet port. Particle Retention: The ability of wire cloth to prevent the passage of solids, or the smallest size of particle retained by a given mesh, usually expressed in microns. Plain Weave: Wire cloth woven so that each shute wire passes alternately under and over successive warp wires and each warp wire passes alternately over and under successive shute wires. Rim Bound: Pack screens that feature single or multiple layers of wire cloth, with the edges enclosed with a formed metal rim. The rim acts as a gasket for improved sealing. Selvage: A "finished" woven edge along the sides of a roll of wire cloth. This should be specified when required, as most wire cloth is fabricated with cut edges. Shattered Metal Powder: Powder consisting of loose, irregularly shaped metal particles used in pack filtration. Shute: Wires The wires running the width of wire cloth, perpendicular to the warp wires. Also known as "weft wires" or "fill." Sintered Metal: Powder Metallic powder sintered to form a rigid, durable filter structure. Sintering: Metallurgically bonding porous metal filter media, using heat (2,000 degrees), pressure, and time. Slitting: The cutting of existing rolls of wire cloth to customer-specified widths. Slow Hole: Reduced flow in a spinnerette hole that is caused by contaminants or uneven distribution across the spinnerette face. Spinnerette: Precision-manufactured plate with small holes through which polymer passes to form filaments. Holes range in size from 40 to 500 microns. Spin Pack: Filtration device housing the spinnerette and filter media. Square Mesh: Wire cloth with equal spacing of warp and shute wires to produce square openings. Top Hat: Three-dimensional screen within a spin pack. The screen is similar in shape to that of a top hat. Twilled Weave: To achieve a finer degree of filtration with heavier wire diameter, warp and shute wires are woven over two and under the next adjacent pair of wires. Warp Wires: Foundation wires, running the length of wire cloth.  |
