17 DEC 2003
5-3.2.3 Media Housing System. Filter housings are an integral part of cartridge filtra-
tion in that they need to be compatible with the system pressure and operating tem-
perature, handle corrosive fluids, economically house the number of cartridges required,
provide reliable seals to prevent fluid bypassing, and allow for easy replacement of filter
5-184.108.40.206 To handle corrosive waste streams, housings can be constructed of a variety
of steel and nickel alloys with multiple type liners available. Housings must meet pres-
sure vessel codes, and if temperature needs to be maintained to prevent solidification of
some fluids, a heated jacket for some filter housings is available.
5-220.127.116.11 Filter housings can accommodate numerous filter elements that operate in
parallel. As demonstrated above, systems that use multiple filter elements tend to have
greater solids holding capacity per unit length of filter.
5-18.104.22.168 One of the most important features of filter housings is the sealing system
that prevents bypassing of the filter. A common seal uses double open-ended cartridges
and a squeezing mechanism on the housing. Piston type O-ring seals are most often
used in single cartridge housings.
5-22.214.171.124 Cartridge elements have the designation DOE for double open ended seals
and SOE for single open-end designs. The most common sealing system in multi-car-
tridge units is the DOE design. The DOE design provides a knife-edge or flat gasket
seal on the seat at the top of the filter cartridge.
Operating Conditions. Filters are changed either at predetermined time
intervals, based on projected flow rates and contaminant levels, or when the pressure
differential across the system restricts the flow through the unit, or when effluent quality
degrades because the cartridge filter deforms. Depending on effluent quality needs, fil-
ters may be staged through a pre-filtration arrangement, according to removal rating,
thereby minimizing cost for small pore size filters. System parameters that affect filter
selection include temperature, pressure, fluid compatibility, removal efficiency, fluid vis-
cosity, type and quantity of contaminant, maximum allowable pressure drop across the
filter assembly, required throughput, and flow rate.
5-3.3.1 Temperature. Glass, ceramic, and metal filters are the most commonly used
filters where continuous operating temperatures exceed 260 degrees C (500 degrees
F). In the temperature range of 150260 degrees C (302500 degrees F) fluorocarbon
filters as well as glass, ceramic, and metal filters are often used. From 80260 degrees
C (176-500 degrees F), almost all other media types can be used provided metal hard-
ware is used. Below 80 degrees C (180 degrees F), all filter media can be used with ei-
ther plastic or metal hardware. Refer to Table 5-7 for maximum operating temperature
for each filter material.
5-3.3.2 Pressure. System pressure is needed to maintain flow as the cartridge accu-
mulates particles. In determining operating pressures, the designer must also consider
the pressure necessary for other resistances, such as pipe elbows and valves. Exces-