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S-RING COVER
A method of sewing the ring cover onto a bag in which the ring is in the top of the "T" and the two ends of the ring cover are sewn flat together against the bag.

SAFETY GROUND DEVICE
A device for physically grounding the high voltage system prior to personnel entering the precipitator. The most common type consists of a conductor, one end of which is grounded to the case, the other end attached to the high voltage system using an insulated operating lever.

SATIN WEAVE (SATEEN)
The weave produces a fabric with a characteristically smooth surface by employing a greater number of yarns in the set of threads that form the face of the fabric surface.

SCFM
Standard Cubic Feet per Minute. The volume of gas flow per minute at standard temperature and pressure conditions (70°F at sea level).

SCOURING
Process of removing the starches and lubricants applied to fabric to protect it during weaving. Fabrics that have been scoured are generally softer and better withstand cleaning action.

SCREW CONVEYOR
A revolving screw operating in a fixed trough for conveying material through the system from one point to another.

SCRIM
An open mesh, plain-weave cloth used as the base in some felted fabrics.

SCRIM SPLICE
Occurs in felt type material when the base fabric is joined at the mill. Normally hard to see if done properly.

SCRUBBER
Any device in which a contaminant, solid or gaseous, is removed from a gas stream by impacting it with liquid droplets. (Types include spray towers, packed towers, cyclone scrubbers, jet scrubbers, venturi scrubbers and impingement scrubbers.)

SELF SUPPORTED
A nonwoven fabric that has been processed to interlock the fibers such that a scrim is not required.

SEQUENTIAL CONTROLLER
An Enclosure that contains the primary timer board used for activating the baghouse cleaning system at a preset timed sequence. Many also contain a gauge to display differential pressure.

SHAKER BAGHOUSE
A baghouse where cleaning is accomplished by manually or automatically shaking the bags. The particulate is collected on the inside of the bags.

SILICONE FINISH
A treatment of filter bags to help provide a slick finish for improved dustcake release.

SINE WAVE
A wave form consisting of a positive and negative half cycle, each one lasting 8.33 milliseconds. Based on U.S. power generation at a 60-hertz cycle.

SINGING (SINGED FINISH)
The process of burning off fibers protruding from fabric surface by passing it over a flame or heated copper plates. Singing gives the fabric a smoother surface, which aids in dustcake release, particularly in applications where moisture is a problem.

SIZING
A starch lubricant that is used to protect the yarns during the weaving process.

SKIPPED STITCHES
A missed stitch; i.e., the needle and looper or bobbin thread are not interconnected, causing the thread to simply lay on the surface of the fabric. Caused by tension, worn or cracked looper, and malfunctioning bobbin case, worn or dull needles. Could also be machine timing.

SLIDE GATE
A material discharge device consisting of a plate held in place by a flanged frame and sealed with gaskets. When the hopper above the slide gate needs to be emptied, the plate is slid open and the material discharges. Used for intermittent dumping where dust loads are light. Also used interchangeably with "blast gate," a similar device used as a damper to regulate airflow in a duct.

SLIP
The proportion of dust escaping from the precipitator outlet. Slip may be expressed as a decimal fraction, or a percentage. It is usually estimated by dividing the outlet dust burden by the inlet dust burden.

SLIT WIDTH
The flat width of a given fabric prior to tubing.

SLITTER
Mechanical machine equipped with knives, which are used to cut down larger rolls to a smaller size.

SNAPBAND
A stainless steel band with a gasket attached sewn into a cuff or extended cuff to provide a positive seal between the baghouse sections.

SNEAKAGE
The process in which dust-laden gas passes between the precipitator casing and the electrode system, either over the top or around the edges. Each percent of gas sneakage reduces the attainable precipitator collecting efficiency by almost 1%.

SOLENOID VALVE
Often times referred to as a "pilot valve," it is an electromechanical plunger energized to either a "normally closed" or "normally open" position to allow for relief of air pressure. The solenoid valve is normally used to activate a compressed air device.

SONIC CLEANING
Sonic energy from air-powered horns which produc shock waves, which enhance dust removal from fabrics.

SPARK
A short, self-extinguishing discharge from the high voltage system to the grounded system. Sparks effectively cause the gas stream to act as a conductor.

SPECIFIC COLLECTING AREA (SCA)
A figure obtained by dividing total effective collecting surface of the precipitator by gas volume expressed in thousands of actual cubic feet per minute.

SPECIFICATION
The document that describes in detail the requirements with which a product or service has to comply.

SPLICES
Mechanical union of fabric roll ends, most often made by a sewing machine.

SPRAY TOWER COOLER
A tower or cylinder into which a hot gas stream enters and water is sprayed. As the water evaporates, the gas stream is cooled to the desired exit temperature.

SPUN YARN
A yarn consisting of fibers of a regular or irregular staple length usually bound together by twisting, providing more surface area for particulate capture.

SPUNBOND
A non-woven fabric formed by producing, laying and self-bonding a web of filament material in one continuous set of processing steps. Usually made of polyester, polyamides or olefins.

STAPLE FIBER
Short fiber cut to specific length in synthetics to either form yarns or nonwoven felts.

STATIC PRESSURE
The potential pressure exerted in all directions by a fluid at rest. For a fluid in motion it is measured in a direction normal to the direction of flow. Usually expressed in inches water gauge when dealing with air.

STATIC PRESSURE DROP
The change in static pressure as the gas stream goes through the filter media and the filtration system ductwork.

STITCHES PER INCH
The term describes the number of stitches in a seam in a given inch. Should not be measured on machine start-up or rundown; machine should be running at full speed.

SURFACE FILTRATION
A process that traps contaminants larger than the pore size on the top surface of the filter, usually a PTFE membrane. Contaminants smaller than the specified pore size may pass through the membrane or may be captured within the membrane by some other mechanism.