Industries Information

Test sieves are woven wire or perforated metal pans that are used for sifting and filtration.  Test sieves are accurately constructed by placing wire cloth between two suppressed die formed frames.  Stainless steel or brass is generally used in the construction of both the frame and woven wire mesh that performs the straining.  These devices are very accurate, and are widely used in all types of laboratory particle analysis.

Test sieves are available in a variety of standard diameters (3, 5, 6, 8, 10, 12, and 18 inches, and 200, 300, or 400 mm). Specialized or proprietary sizes, either larger or smaller, are also available, although far less common.  Test sieves are also available in a variety of heights, either full height (typically full height is 2 5/8"), half height (typically 1 5/8”), or a variety of intermediate sizes between.

Test sieves are engineered to the rigorous standards of the International Organization for Standardization (ISO), Standard 3310-1, or to the U.S. Standard as per ASTM E-11.  Additionally, precision electroformed sieves are standardized to ASTM E161, while perforated plate sieves are manufactured to ASTM E323, or the British Standard BS140-1, as well as ANSI 2000.  All of these Standards detail a number of specifications to which any rated test sieve will adhere.  These ratings include permissible opening sizes, opening dimensions, maximum number of allowable openings in each test sieve, and nominal wire diameter.

Test sieves are available in a number of specific configurations.  These include certified, matched, calibrated, matched and calibrated, and midpoint.  Certified are the most widely used test sieves and are manufactured to a National or International Specification. Each is supplied with a Certificate of Conformity and individually numbered to provide full traceability.  Matched style is comprised of two or more test sieves each fitted with a sieving medium having similar aperture characteristics. Each is supplied with a Certificate of Conformity.  Calibrated sieves are calibrated in accordance with the specification. Each sieve is supplied with a calibration test certificate giving the range of tolerances and measurements taken.  Midpoint test sieves are fashioned from a more precise sieving medium where specification tolerances are reduced by 30% where attainable. Each sieve is supplied with a test certificate giving the range of tolerances and measurements taken.

Some test sieves are supplied with top covers and/or bottom pans.  Top covers serve to contain the media dust or filtered matter within the sieve when under vibration and also keep the sieve clean when not in use.  Bottom pans collect the sieve media or filtered matter for future use.

Strainers are placed in-line with process piping to remove large solid contaminants from the flow.  Strainers can be cleaned and reused. Strainers can be supplied as either an assembly or an element.  Strainer assemblies come equipped with a housing, cover or case, and a strainer element. Strainer elements, when sold separately, do not come as a complete assembly.  A strainer element is a simple mesh or perforated metal element that may be used as replacement or a handheld strainer.  Strainers can be used in a wide variety of applications, including but not limited to: general purpose, chemical, coolant, food processing, laboratory, industrial, high temperature, high viscosity, hydraulic fluid, medical or pharmaceutical, oil or fuel, refrigerant and water.

Strainer types can be basket or simplex basket, duplex basket, in-line, tee type, y-strainers, conical line or flat plate.  A simplex basket strainer is used where the line can be shut down for short periods to clean or change baskets. It becomes an integral part of the pipeline and all flow passes through it.  Duplex strainers remove damage causing particulate matter from the process media, and never have to be shut down for cleaning.  The line can run continuously. When one strainer basket becomes full, flow is switched to the other. The first basket is removed, cleaned and is ready for use again.  Some basket filters are ‘temporary’ and are intended for start-up use only.  In-line strainers are positioned with the basket parallel to the line of fluid flow.  They are often used in sanitary applications.  Tee type strainers are particularly adapted where basket replacement needs to be made quickly.  Y-strainers are devices for mechanically removing solids from flowing liquids or gases by means of a perforated or wire mesh straining element. They are used in pipelines to protect equipment such as pumps, meters, control valves, steam traps, and regulators.  Conical line strainers are used to protect fluid and gas handling equipment by removing debris during the start-up of a system. They are easily installed between large flange faces without modifying the surrounding pipe work and they are easily removed.  They are "temporary" strainers and are intended for start-up use only.  Flat plate strainers are inserted directly in the line of fluid flow.  They may also be used while held in the hand.  They are "temporary" strainers and are intended for start-up use only.

Strainers remove solids from a fluid line.  Some strainers may be available for specific types of media only.  Specific media types include liquids, gases, steam, and slurries.  Selection of strainers is dependent upon the pipe size of the process line or the nominal pipe size that can be accommodated by the strainer.  Strainers will have a maximum service design pressure that should be specified.  The screen opening is important to consider as well The standard most widely used in North America is ASTM E-11 standard (American Society for Testing Materials).  The opening is defined by a number (number 635 (20 µm) to number 3-1/2 (5.6 mm)) or is defined in inches (1/4 in. (6.3 mm) to 5 in. (125 mm)).  The standard used in Canada in the field of construction materials is ISO 3310-1 standard (International Standards Organization). The opening is defined in micrometers (20 µm to 37,500 µm).  Strainer selection also depends on process temperature; the full required range of ambient operating temperature.

Strainers can have a connection that is welded, flanged, threaded, clamped or brazed or soldered.  Materials of construction are typically bronze, cast iron, nickel alloy, carbon or alloy steel, stainless steel, titanium, polyvinyl chloride (PVC), polyethylene (PE), or polypropylene (PP, PPL).  Features common to strainers include integral filters, magnetic inserts, steam jacketing, self-cleaning, and sanitary construction.

Separation equipment and filtration equipment for liquid-solid materials are used to filter, thicken or clarify a mixture of different elements.. Examples of liquid-solid separation equipment and filtration equipment types include sedimentation equipment, gravity filtration equipment, vacuum filtration equipment, pressure filtration equipment, thickeners, clarifiers, and centrifugal separators. Sedimentation is a gravitational or chemical process that causes particles to settle to the bottom.  Sedimentation equipment includes gravity sedimentation filters and flocculation systems.

Gravity filtration uses the hydrostatic pressure of the prefilter column above the filter surface to generate the flow of the filtrate.  Gravity separation equipment and filtration equipment includes bag filters, gravity nutsches and sand filters.

Vacuum filters are available in batch (vacuum nutsches and vacuum leaf filters) and continuous (drum filters, disk filters and horizontal filters) operating cycles.  Continuous vacuum filters are widely used in the process industry.  The three main classes of continuous vacuum filters are drum, disk, and horizontal filters.  All of these vacuum filters have the following common features:

- A filtering surface that moves from a point where a cake is deposited under a vacuum to a point of solids removal, where the cake is discharged through mechanical or pneumatic means, and then back to the point of slurry application.

- A valve to regulate pressure below the surface.

- An apparently continuous operating cycle that is actually a series of closely spaced batch cycles.

Vacuum Separation equipment and filtration equipment for liquid-solids includes disc filters, horizontal belt filters, rotary drum filters (including precoat varieties), table filters, tilting pan filters, tray filters, and vacuum nutsche filters.

Pressure filters operate at superatmospheric pressures at the filtering surface.  The media is fed to the machine by diaphragm, plunger, screw and centrifugal pumps, blowcases and streams from pressure reactors.   Most pressure filters are batch, or semi-continuous, machines.  Rotary drum pressure filters and some others have continuous operating cycles.  Continuous machines are more expensive and less flexible than batch machines.  Pressure Separation equipment and filtration equipment includes automatic pressure filters, candle filters, filterpresses, horizontal plate pressure filters, nutsche pressure filters and vertical pressure leaf filters.

Thickeners are used to separate solids from liquids by means of gravity sedimentation. Most thickeners are larger, continuous operation pieces of equipment. They are used for heavy-duty applications such as coal, iron ore taconites, copper pyrite, phosphates and other beneficiation processes. Common thickener types include conventional thickeners, high rate thickeners, lamella thickeners and tray thickeners.

The primary end product of clarifiers is a clarified liquid.  They are virtually identical in design to thickeners, but have a lighter duty drive mechanism.  They are generally used for industrial and residential waste.  Clarifying separation equipment and filtration equipment includes conventional clarifiers, reverse osmosis equipment, sludge-blanket clarifiers and suction clarifiers.

Industrial fluid filtration equipment is used to filter dirt, swarf and other contaminants out of industrial fluids such as oils, cutting fluids, and coolants. There are many different types of industrial filtration products. Some industrial fluid filtration equipment uses bag, cartridge, or crossflow filters. Other products use reverse osmosis membrane, pressure vessel, gravity or vacuum filters. An automatic industrial fluid filtration system cleans filter media by removing trapped contaminants through backwash or gravity deposits of filter cake. Cross-flow filtration, which uses a portion of the fluid to carry away contaminants, is used to extend the life of membrane filters. Oil filtration is an industrial filtration product that includes the removal of water, gas, and particulate matter. Coolant filtration requires the removal of contaminants and maintenance of the chemical balance of the coolant. Cutting fluid filtration extends the useful life of cutting fluids, which are used in machining operations such as turning, drilling, and milling.

Specifications for industrial fluid filtration equipment include: means of fitting to existing equipment such as pipelines, flow rate in gallons per minute, filter efficiency, working and static pressure (for pressure filters), woven or non-woven medium, and method of removal of filter cake. An industrial filtration product can use surface filtration, in which contaminants load at the surface of the medium, or depth filtration, in which contaminants load throughout the medium. Industrial fluid filtration equipment can also alert operators to the need for maintenance, such as filter changes.

Industrial fluid filtration equipment differs in terms of approvals and certifications. Technical Committee 131 of the International Organization for Standardization (ISO) maintains standards for industrial fluid filtration systems. For example, ISO 4406 defines levels of solid particle contamination in hydraulic fluids. Industrial fluid filtration equipment may also be required to meet design standards. For example, some pressure filters meet the requirements of the Boiler and Pressure Vessel Code maintained by the American Society of Mechanical Engineers (ASME). In the European Economic Area (EEA), an industrial fluid filtration system such as a pressure filter must comply with European Pressure Equipment Directive (PED) 97/23/EC.

 Filtration media and elements are designed to remove suspended debris from a process stream. Filtration is a physical or mechanical process which removes insoluble particles from a liquid or gas. Base fluids may include coolants, corrosive chemicals, gasoline, diesel fuel, hydraulic fluid, lubricants, water, oil, inks, dies, and paints. Particulates and contaminants can also be filtered from gas or air. Filtration grade or Beta ratio is the most important specification to consider when selecting filtration media and elements. This micron-rating characterize a filter’s ability to remove contaminants based on particle size. Water absorption, pressure drop, maximum liquid flow, and maximum gas flow are also important parameters to consider. Choices for housing material include: aluminum, plastic, steel, stainless steel, and Teflonregistered: ® (DuPont Dow Elastomers).  Some filtration media and elements are portable, reusable, or disposable. Others have an integral bypass, provide high Delta P indication, or meet requirements from the U.S. Food and Drug Administration (FDA).

There are four main configurations for filtration media and elements: bulk filter media, cartridge, housing only, and housing and filter assembly. Bulk filter media has a defined, porous structure and serves as a particle collector. Filtration media and elements in this category include only the filtration media itself; cartridges, holders, and other receptacles are sold separately. Types of bulk filter media include: activated carbon, activated clay, cellulose, ceramic, cotton, diatomaceous earth (DE), glass fiber, ion exchange resins, metals, minerals, paper, nylon, sand, synthetic fiber, Teflon, polyethersulfone (PES), polyester, polypropylene (PP), polytetrafluoroethelyne (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), and polysulfone. The base fluid and media type determines the bulk filtration media to select.

The filtration media and elements product category also includes cartridges, housing-only products, and housing and filter assemblies. Cartridges hold the bulk filter media and perform the actual process of filtration. Cartridges do not have moving parts, but perform filtration passively as fluids pass through. There are two basic types of cartridges: pre-filled disposable and refillable. Pre-filled disposable cartridges include a specific filtration media sealed within. Their length-of-use is determined by the bulk filtration media and the amount of particulate to filter. Most refillable cartridges do not include filtration media. Housing-only products are ported enclosures that direct the flow of fluid through the filter element. Housing and filter assemblies are built-in cases or enclosures that cover and/or protect the filter assembly.