Filtration-Basic Concepts

1.Vocabulary

No. Terms Definition Notes
1 Filter General term for a porous medium that is able to separate particles
of different sizes, ahapes, or materials		 JIS K3802
2 Element General term for a product fabricated from filter paper and other
man made materials and used in a pressurized filter housing		 JIS K3802
3 Strainer General term for an element fabricated using mesh(metal or
polymer) as its filter meduim		  
4 Cartridge General term for product that encloses a filter element in a
metal housing that allows the complete filter to be easily
replaced(i.e. spin-on type filter)		  

2.Filter media

No.

 Type Filtered Particle Size Description
1 Mesh 15-2,000 micron meter Fabricated using a metal or polymer mesh
2 Fiber 0.6-50 micron meter Fabricated using either cellulose, polymer,
or glass fibers or metal thread

3.Basic Filter Ratings

No. Terms Description No. Terms Description
1 Filtration Rating Diameter of the smallest particle which the filter is more
than 99.9% effective in
filtering out of the solution		 5 Mechanical
Strength		 As measured in Durability
Tests-End Load Strength Tests-Flow Fatigue ResistanceTests-Collapse
Strength Tests
2 Filtration
Efficiency		 A filters ability to capture particles of a specified diameter 6 Chemical Strength As measured in Chemical/Solvent Resistance
Tests
3 Pressure Loss The pressure produced when
the solution passes througth
the filter media		 7 Heat Strength As measured in Heat Resistance
Tests
4 Filter Life Measured either by (a) the time
it takes to reach a differential
pressure of 0.1MPa or (b)
the amount of particles the
filter can capture before
the differetial pressure reaches
0.1MPa		 8 Initial Cleanliness Weight and number of particles
initially contained in the unused
filter that could contaminate
the solution.

4.Filtration Rating Methods and Testing Procedures

4-1. Filtration Efficiency

4-2. Filtration Rating

A rating given to a filter using the test procedure spelled out in JIS B8356

4-3. Nomimal Filtration Rating

A micron rating given to a filter by its manufacturer.

4-4. Beta Ratio(Filtration Ratio)

The Beta Ratio is measured during a Multi-Pass Test. The Multi-Pass Test Method is specified in
either ISO 4572 or ANSI B93.31.
This test uses the filter circuit shown below. In order to approximate real life condition's, a specified
concentration of particles is circulated througth the circuit and test filter.
Particle counts are taken until a specified differntial pressure is reached. The Beta Ratio is one
of the impotant filter ratings obtained througth this test. The Beta Ratio is the ratio of (a) the
number of particles larger than size X upstream of the filter divided by (b) the number of
particles larger than size X downstream of the filter. The larger the Beta Ratio,
the better the filter rating.

Multi-pass test circuit

Multi-pass test circuit

5.Relative Filtration Ratings

Filter Type

Grade(micron meter)

Beta Ratio
1 3 6 10 12 25 30

Inorganic
Fiber

 1

>=1000

 - - - - - -
3

>=75

 >=200 >=750 >=850 >=1000 - -
6

>=4

 >=35 >=200 >=750 >=1000 - -
12 - >=3 >=5 >=75 >=200 - -
25 - - >=5 >=10 >=20 >=200 -

Cellulose

 30(Nominal) - - - >=1.4 - >=3 >=10


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Pressure Conversion Chart


Mpa bar kgf/cm2 lb/in2 ton/ft2 Standard
atmosphere
pressure		 Mercury manometer Water manometer
mter inch meter foot
1 10.00 10.197 145.0 9.324 9.869 7.501 295.3 101.97 334.6
0.1000 1 1.0197 14.50 0.9324 0.9869 0.7501 29.53 10.197 33.46
0.09807 0.9807 1 14.22 0.9144 0.9678 0.7356 28.96 10.000 32.81
0.006895 0.06895 0.07031 1 0.06429 0.06805 0.05171 2.036 0.7031 2.307
0.10725 1.0725 1.0937 15.56 1 1.0585 0.8045 31.67 10.94 35.88
0.101325 1.0133 1.0332 14.70 0.9447 1 0.760 29.92 10.33 35.90
0.13332 1.3332 1.3595 19.34 1.2431 1.3158 1 39.37 13.60 44.60
0.003386 0.03386 0.03453 0.4912 0.03157 0.03342 0.02540 1 0.3453 1.133
0.009807 0.09806 0.10000 1.422 0.09143 0.09678 0.07355 2.896 1 3.281
0.002989 0.02989 0.03048 0.4335 0.02787 0.02950 0.02242 0.8827 0.3048 1


Comparative table of JIS-ASTM-TYLER screen


JIS

ASTM

TYLER

Reference characteristic values

Nomimal size(micron)

Sieve opening(mm)

 No. No.
(mesh)		 Spatial modulus
(%)		 Mesh
(Wires/inch)		 Wire diameter
(mm)
37 0.037 400 400 34.5 400 0.026
44 0.044 325 325 37.3 350 0.028
53 0.053 270 270 33.9 280 0.038
63 0.063 230 250 38.1 250 0.039
74 0.074 200 200 34.0 200 0.053
88 0.088 170 170 34.9 170 0.061
105 0.105 140 150 36.0 145 0.070
125 0.125 120 115 34.8 120 0.087
149 0.149 100 100 34.3 100 0.105
177 0.177 80 80 31.0 80 0.141
210 0.210 70 65 33.5 70 0.153
250 0.250 60 60 34.8 60 0.174
297 0.297 50 48 31.5 48 0.232
350 0.350 45 42 32.9 42 0.260
420 0.420 40 35 35.0 36 0.290
500 0.500 35 32 40.1 32 0.290


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