Milton Industries Lubricator 1132-8 - Form 8X801 - Manual (Page 2)

Although you may think a big filter is more
effective, the reverse may actually be true if
too little air passes through. Always select
filter size based on your air flow or SCFM
requirements.
How small is too small - As long as the
pressure difference between the inlet and
the outlet of the filter does not exceed 3 PSI
at the required air flow (SCFM), the filter is
not too small. For more information, please
refer to the FRL sizing chart in the Milton
Catalog, page 60.
What a filter does and doesn’t do - A
properly selected and
installed filter removes
particulate matter and
water condensate.
However, it does not and
cannot remove water
vapor from the air. Water vapor must be
converted to water condensate before this
type of filter can remove it (See the OTHER
FILTERS section).
Water vapor and water condensate -
Water vapor is an invisible gas; water
condensate is a liquid, even if it is in mist or
droplet form. To convert water vapor to a
condensate, the air must be cooled down -
actually, down to or below the "dew point."
The dew point is the temperature at which
dew or water condensate forms. It varies
with the RH (Relative Humidity). It’s low with
low RH and approaches ambient
temperature with high RH.
This explains why you sometimes see water
droplets or mist coming from a blow gun or
paint sprayer when there is no "apparent"
water in the air lines. The rapid expansion of
the air as it leaves the blow gun or sprayer
causes the air’s temperature to drop (same
principle as an air conditioning system). If
this temperature falls below the dew point,
the water vapor in the air line converts instantly
to water condensate.
MICRO-FILTERS
Although the Micro-Filter is the simplest of
the three basic air control devices, it is also
the least understood and the one most
frequently installed improperly. Read on.
How they work -These filters remove two
kinds of contaminants: (1) solid, particulate
matter such as rust and pipe scale and (2)
water condensate. The first is removed by a
nominally rated 40 micron porous sintered
metal element. However, because of it’s
unique "tortuous path" design, it will actually
trap particles down to 10
microns in size (about
0.0004 inches)
The water is removed
through a violent swirling
action imparted to the air by a set of fixed
vanes at the top of the filter. The process is
exactly like that of the spin-dry cycle in a
washing machine. Centrifugal force throws
the water droplets against the side of the
bowl where they roll down and collect at the
bottom.
Small is better -The more rapidly the air is
swirled, the more effectively the water
condensate is thrown out against the filter
wall. If you pass the same volume of air
(SCFM) through a small filter and a large
filter, it will swirl more rapidly in the small one.
Condensate removal in a Micro-Filter.
" The filter ... is the one least
understood and the one most
frequently installed improperly "
If you sometimes experience a problem like
this, you will require, in addition to the Micro-
Filter, a desiccant dryer filter (see OTHER
FILTERS section).
Choosing a different drain system -
All filters (except the Mini) come with an
Overnight Drain that opens when line
pressure falls, after turning off the
compressor, to 5 PSI. These drains can also
be opened manually by pushing them
sideways (poly bowls) or twisting them in the
direction of the arrow (metal bowls).
You can also install an Automatic Drain
Valve (Model 1168) in place of the supplied
Overnight Drain Valve. These valves open
automatically whenever the water level in
the bowl reaches a certain point, whether
the system is under pressure or not. These
are good for high humidity conditions or
around-the-clock systems.
Metal bowl vs. polycarbonate bowl -
The advantage of the poly bowl is in quick
and easy water level checking. If you have a
situation where water may fill the bowl
before the overnight drain can function (e.g.,
high humidity), it is helpful to be able to
visually check water level.
Other than this, the advantage is with the metal
bowl. This is especially true if you are using
synthetic oils in your compressor or have
volatile solvents in the area. (See list of
chemicals that are not compatible with poly
bowls.)
One filter is never enough - A well -
designed system requires a minimum of two
filters: (1) a master filter near the
compressor and (2) a smaller filter at each
work station or air operated device. The master
filter is usually a 1/2" NPT or larger unit.
This filter should never be installed at the output
of the compressor, but rather at the output of
the after-cooler or the receiving tank. These
units allow the hot, high pressure air from the
compressor to cool down enough to condense
out much of the water vapor. The main line filter
and regulator should be placed at least 20 Feet
from the compressor.
The additional filter at each station, besides
removing still more condensate, also traps any
debris (rust and pipe scale) that may make its
way down the distribution pipe. Try to locate this
filter as close to the device as possible.
Installation tips - Align the filter vertically, with
the drain at the bottom. Note that the air from
the compressor enters the "IN" port and exits
the "OUT" port. If connected backwards, the
filter will still pass air but will not extract the
water condensate.
Easy maintenance - Since there are no
moving parts to wear out, there is little to go
wrong. Periodically wash the sintered filter
element in a detergent solution and blow it out;
if too clogged to be washed, replace it.
Sometimes a Micro-Filter alone is not the
answer. Although they remove much of the
water, in some applications, such as spray
painting, it’s not enough.
When you need exceptionally dry air or
essentially oil-free air, you can choose from two
other filter types: (1) the desiccant dryer and (2)
the oil removing filter.
The desiccant dryer filter - This is the ultimate
filter for dry air; it takes over where the Micro-
Filter leaves off. This filter absorbs directly,
through a chemical process, the water vapor in
the air.
So effectively does it remove water, that the air
frequently has a dew point of 0
° F or lower.
OTHER FILTERS
AIR IN AIR OUT
FIXED VANES
WATER DROPLETS
WATER
CONDENSATE
DRAIN
SINTERED FILTER
BAFFLE
When you need a desiccant dryer
Page 2 / REV 03-2008