Solutions Q&A 05
2.1 General overview
Three main types of filters exist: The general purpose filter for water and
particles, the coalescing oil removal filter for oil aerosols and the activated
carbon filter for the removal of oil vapors.
The general purpose filter is used for most filter applications and is available
from 1/8" to 2" pipe sizes. Uses are main headers, branch lines, tools,
cylinders, valves and valve circuits, air agitators etc. Oil removal filters are
used where very clean, oil-free air is required, such as for the supply to
fluidic devices, instrumentation, air gauging equipment and air bearings.
Activated Carbon filters are used for systems where the oil vapors in the air
are not acceptable; such as instrumentation and paint spraying.
? 2.1.1 How do general purpose filters work?
The dirt and moisture-laden air enters the inlet port and is directed into the
louvers which centrifugally separate the entrained liquids and dirt which fall
to the bottom of the bowl. Near the bottom of the bowl a baffle creates a
quiet zone, preventing the turbulent air re-entraining the contaminants. The
air, now free of water droplets and large particles, passes through the filter
element which removes small particles.
? 2.1.2 How do oil removal filters work?
The fine oil mist is coalesced (merged) as it passes through the fine fibrous
filtration media. These oil droplets are collected in the outer sock and then
drop from the element to the bottom of the bowl for easy removal.
Where a coalescing filter is being used for oil removal, the element quickly
becomes saturated which is clearly visible on the outer sock. This is the
normal operating condition for oil removal.
Bowl
Bae
Drain
Service indicator
(optional)
Body
Louver
Center post
Element
Metal bowl
sight glass
Collected
condensate
General purpose filter
Bowl
Drain
Service indicator
(standard)
Body
Element
Outer sock
Metal bowl
sight glass
Collected
condensate
Coalescing filter
F74G General purpose filter without
optional service life indicator
F74C oil removal (coalescing) filter
with service life indicator
