17 DEC 2003
Maximum viscosity of the fluid to be treated.
8-3.5.7 The designer can now use vendor literature to determine the number of filters
required for design flow rate. Based on the system flow, the designer must next select a
flow rate per unit filter. The designer needs to confirm from the filter supplier or their
specification bulletin what the maximum flow rate per unit filter or flow rate per unit area
of filter is. In the case of this example, the supplier would need to be contacted. To de-
termine the number of filters required the following equation can be used:
System flow rate / flow rate per unit filter
The number of filters used can be altered by using filters with lengths greater than 250
mm (10 in.). There are standard cartridge filter lengths up to 1 m (40 in.).
8-3.5.8 To determine the pressure drop per filter use the water flow rate/differential
pressure curves as shown in the design example appendices. Each supplier must be
consulted to determine how they account for fluid viscosities greater than 1 centipoise
(one centipoise being clean water at standard temperature and pressure).
8-3.5.9 Having identified the number of cartridges, the system housing needs to be
selected. As with the filter, the materials of construction should be chosen based on
compatibility with the waste stream being treated, including chemical compatibility, tem-
perature, and operating pressure. The internal components of the housing need to be
selected so that they are compatible cartridge ring configurations. The following housing
components need to be specified by the designer.
Ring cartridge configuration.
Materials of construction.
Number of and length of filter elements per housing.
Inlet and outlet styles, side inside out, side inbottom out
8-3.5.10 The number and length of filter elements per housing is not only determined
by the number and length of filters needed by the design but it is also based on stan-
dard housing configurations from the supplier. For example, the system may require the
use of 500- by 500-mm (20- by 20-in.) filters but the supplier's standard housing may be
designed for 600- by 500-mm (24- by 20-in.) filters. In this case the four extra filters will
improve performance. If the supplier's standard housings accommodate some number
of filters less than the design quantity, then the designer should consider the effect on
performance from the increased hydraulic and solids loadings, or consider parallel op-
eration of smaller housings.
8-3.5.11 Inlet and outlet style selection is based on how the filter housing is to be piped
into the rest of the system and not necessarily on system hydraulics. Items such as inlet
and outlet connections are often selected by the supplier based on the maximum flow
ratings per filter system.