Page 264 - Parker - Hydraulic and Lube Filtration Products

Appendix

Defi nitions

Absolute Rating: Cleanliness Codes:
The diameter of the largest hard spherical particle A representation of a fl uids contamination level based
that will pass through a fi lter under specifi ed test on a series of index numbers that refer to a table of
conditions. This is an indication of the largest opening concentration values.
in the fi lter element. Hydraulic Filter Division defi nes
absolute as 99.5% removal (beta 200) at a given
particle size.

Absorb/Absorption:
The process of a fl uid being taken into the pores
of a solid.

Adsorb/Adsorption:
To collect and hold a fl uid on the surface of a solid.

Beta Ratio:
The ratio of the number of particles of a given size and
larger of a fi lter to the number of particles of the same
size and larger downstream.

Beta Ratios/Efficiencies
Beta Ratio Capture Efficiency
(at a given particle size) (at same particle size)
1.01 1.0%
1.1 9.0%
1.5 33.3% Collapse Pressure:
2.0 50.0% An inward structural failure of the fi lter element caused
5.0 80.0% by excessive differential pressure.
10.0 90.0%
20.0 95.0% Contaminant:
75.0 98.7% Undesirable insoluble solid or gelatinous particles
100 99.0% present in fl uid.
200 99.5%
1000 99.9%
Crest:
The outer fold of a pleat.
Bubble Point:
Pressure drop in inches of water required to expel Differential Pressure/Pressure Drop:
the fi rst steady (continuous) stream of bubbles from Difference in pressure between two points in a system.
a horizontal disc of wetted fi lter medium or a fi lter In fi lters, this is typically measured between the inlet
cartridge immersed in a liquid (usually alcohol). and outlet of the fi lter housing.
A bubble point test is used to test the integrity of
cartridge construction to compare relative porosities Dissolved Water:
of a fi lter media or monitor product consistency as Water capable of being held by the fl uid in solution.
a quality control method. The amount held must be below the saturation point.

Bypass: Duplex Filter:
Fluid fl owing through a passage other than the fi lter An assembly of two fi lters with valving for the
medium and/or leakage around fi lter media seals. selection of either element.

Burst: Effi ciency:
An outward structural failure of the fi lter element The ability of the fi lter element to remove particles
caused by excessive differential pressure. from the fi lter stream. Effi ciency = (1-1/beta)100.

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