True Depth Filtration vs. Claimed Depth Filtration

Many cartridges claim to be depth filters. But to be a true depth filter, a cartridge must be able to retain contaminants throughout the entire cross section of the filter. To accomplish this, the density must increase progressively from the exterior surface to the interior. This "graded density" allows larger particles to be trapped near the surface while smaller particles penetrate the larger open areas to be trapped nearer the center of the filter in the smaller openings. Without graded density, a so-called "depth" filter will operate in practice only as a surface filter. With only the surface area loading with dirt, the pressure drop will increase rapidly, dramatically reducing both the dirt-holding capacity and the effective filter life.

CAT Scans Tell the Truth About Graded Density

CAT Scanning (Computerized Axial Tomography) is a relatively recent breakthrough in diagnostic X-ray imaging technology. In medical applications, it provides detailed cross-sectional images of the human body. Here, CAT scans provide detailed cross-sectional images of cartridge filters.

NOTE: All CAT scanned filters were purchased on the open market and are rated by their manufacturers at 10 microns. All CAT scans were taken with the same scanner at the same setting by the same operator. Lighter areas of the photos indicate greater density.

	Hytrex® II - thermally-bonded blown microfiber matrix- true graded density particles trapped throughout the depth of the filter no separate core highest density at knife-edge seal
	String-wound polypropylene- inconsistent density channels in windings allow particles to penetrate directly into filtrate separate core required
	Single density, polyolefin microfibers- no graded density surface blinding no central core
	Molded, resin-bonded fibers, grooved no graded density (apparent second filtration "surface" is actually the groove cut into the filter to increase surface area) surface blinding
	Layered non-woven microfibers- no graded density low density layers surface blinding separate core required

Performance

TEST CONDITIONS: Several 10 micron filters of each type were purchased on the open market and weighed. They were then challenged with a slurry of 100 ppm AC Fine Test Dust at 5 gpm (1.1 m³/hr) until a 40 psi (276 kPa) differential pressure was reached. All filters were then force dried for 72 hours at 125º F (52º C) and weighed again. The bar chart above illustrates the relative difference in average dirt-holding capacity compared with Hytrex. NOTE: AC Fine Text Dust is the laboratory standard commonly used to characterize cartridge filters with ratings one micron or greater.

TEST CONDITIONS: Several 10 micron filters of each type were purchased on the open market and weighed. Each was challenged with a 100 ppm slurry of AC Fine Test Dust at 5 gpm (1.1 m³/hr) until a 40 psi (276 kPa) differential pressure was reached. The bar chart above illustrates that relative difference in average filter lifetime compared with Hytrex.

A good measure of a cartridge's ionic cleanliness is its "Rinse-Up Time." This is the amount of time required for the resistivity of an 18 megohm deionized water stream to return to its pre-filter resistivity after passing through a new filter cartridge. All cartridges are rated by their manufacturers at 5 microns and were tested at a flow rate of 2 gpm (0.45 m³/hr)

Because of their unique construction and clean manufacturing process, Hytrex filters provide cleaner performance than conventional depth filters. The above data are based on tests using 10 micron Hytrex filters from Hytrex finished good inventory and 10 micron filters purchased on the open market from the leading string-wound and resin-bonded cartridge manufacturers. Each filter was tested on Osmonics^® "Media Migration Test Stand" at a flow rate of 10 gpm (2.3 m³/hr), twice the highest recommended rate, to stress the filters and simulate pressure surges. After a one minute flush to eliminate start-up debris usually present in housing and piping, the particulate migration was collected from the filtrate using membrane filters which were then weighed at the specified time intervals. All tests were run on sample lots of five individual cartridges, and the results were averaged. In all Hytrex filters, the particulate migration at 60 minutes was below the Lowest Detection Limit (LDL) (0.1 mg) of the test equipment. A more complete test protocol is available from Osmonics.

Specifications

Eight Standard Micron Ratings
1,3,5,10,20,30,50,75 Microns

Two Standard Diameters
816GX Series:
Inside Diameter: 1 in. (25 mm)
Outside Diameter: 2 1/2 in. (64 mm)
816RX Series:
Inside Diameter: 1 3/8 in. (35 mm)
Outside Diameter: 2 3/4 in. (70 mm)

End Adapters and Accessories

All end adapters are thermally-welded to the pure polypropylene Hytrex filter. The positive weld assures bypass-proof performance and structural integrity without adhesives or additives, maintaining cartridge purity. All adapters including the elastomeric gasket comply with FDA requirements for food and beverage contact. Adapters and accessories pictured here are immediately available from inventory. Hytrex filters fit all currently available filter housings.

A- Elastomeric seal gasket, open end

E- Pure polypropylene molded adapter with "222" O-rings silicon O-rings standard; EPR, Viton*, Buna-N O-rings available

F- Pure Locking polypropylene molded adapter with locking "ears" and two "226" O-rings silicon O-rings standard; EPR, Viton, Buna-N O-rings available

H- Pure polypropylene molded "fin" complete seal assures alignment

K- Pure polypropylene molded spring replaces metal assemblies provides more positive seal, eliminates bypass easy, quick changeout

L- Pure polypropylene extended core centers filter on tube sheet adapter eliminates tube guide

S- Pure polypropylene closed end cap complete seal other end open

SP- Stainless Steel Support Post 316 stainless steel extends chemical, temperature, viscosity and (delta) P limits of cartridge reusable - more economical than cored cartridges chamfered ends ease cartridge installation 9.75, 10, 19.5, 20, 29.25, 30 and 40 inch lengths

FC- Polypropylene Filter Cage all polypropylene cage holds 15 Hytrex cartridges 30 filter seals reduced to one available in 8 different micron ratings integral eyehook for handling by mechanical equipment - eliminates handling of individual filters standard 10, 20, and 30 inch lengths fits housings accepting cages 13 1/2 inches in diameter flow rates from 45 to 225 gpm (10 to 51(m3/hr) per cage, depending on micron rating of cartridges

How To Order  HYTREX

If you are ordering Hytrex filters with standard Hytrex ends (that is, with no adapter on either end), then pick one boldface designation from each of the first three columns. Your Product Order Number will look like this: 816GX-05-29¼ . 

If you are ordering Hytrex with one or more end adapters, pick additional boldface designations from each of the next two columns. Your Product Order Number will look like this: 816GX-05-29¼ -E-S

EXAMPLE: = 816GX-05-29¼-E-S

* Viton is a registered trademark of DuPont Dow Elastomers L.L.C.
** Silicone O-rings are included. EPR, Viton and Buna-N O-rings are available by special order.
†End adapters not available on 816RX series, except for special 336 type with Self  Seal Spring.
  Note: Stainless steel support posts (SP) should be ordered separately.