UFC 3-280-04
17 DEC 2003
8-3.5.1.3 Observe the solution to see if any chemical reaction has taken place. Check
for changes in color, clarity, viscosity, etc.
8-3.5.1.4 If there has been no perceptible change in the cartridge or solution, then the
filter may be considered for use.
8-3.5.2 Having selected the material of construction, check which materials can oper-
ate in the temperature range of the waste stream to be treated. Some materials can
only operate at temperatures up to 70 degrees C (160 degrees F) while other materials
can operated at temperatures up to 300 degrees C (600 degrees F).
8-3.5.3 Based on influent suspended solids and particle size data, select the micron
rating for the filter to meet desired effluent suspended solids and particle size criteria.
Note that the smaller the micron rating is the lower the solids holding capacity of the fil-
ter. For example, a wound cotton cartridge filtering a liquid with 1 mg/L (1 ppm) solids
feed rate would have the following holding capacities at various micron ratings shown in
Table 8-3. Refer to Paragraph 5-3 for further information.
Table 8-3. Holding capacities of a wound cot-
ton cartridge.
Micron rating
Solid holding capacity
(grams per unit filter)
1
15
5
35
10
60
20
100
8-3.5.4 The above data were generated at a 0.0631 L/s (2.5 gpm) flow rate on a 250-
mm (10-in.) filter and failed at a maximum pressure differential of 207 kPa (35 psi). See
Chemical Engineering(1988) for additional information on selecting cartridge filters. Ac-
tual solids holding capacity should be checked under process conditions, as many filter
manufacturers rate the solids holding capacity under controlled laboratory conditions
and actual solids holding capacity can vary significantly.
8-3.5.5 The fluid viscosity at the operating temperature should be determined. If the
system will be operating under varying conditions, then the temperature that gives the
highest viscosity in centipoise must be known.
8-3.5.6
At this stage of design the following filter selection criteria have been identi-
fied:
Materials of construction for the filter, based on waste stream compatibility
and maximum operating temperature.
Micrometer rating of the filter, based on influent conditions and desired efflu-
ent quality. Typically this information is provided in vendor literature.
Solids holding capacity of the filter from vendor literature or bench or pilot
testing of the process stream.
8-8
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