Table Of ContentCompressed Air Filters
Compressed Air
Filters
Filters of all kinds are found
everywhere in the world, and most of
us are familiar with some of them. On
www.about-air-compressors.com we
are focussed on filters for compressed
air systems. Filters are compressed
air preparation equipment that are
essential for most compressed air
applications.
The proper selection and use of
compressed air filters will prevent
many short and long term problems
with your compressed air equipment
and systems and could save you
substantially in down-time and
component replacement costs over
the life of your compressed air system.
Properly sized filters will also help
prevent poor paint jobs by helping
remove water from the air stream
through the paint gun.
A standard compressed air filter will
contain the following components. The
numbers on the picture of the
compressed air filter picture
correspond to the description in the
text.
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Compressed Air Filters
Filter Components
1) Air Inlet
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Compressed Air Filters
In North America the filter ports have
been traditionally female NPT threads,
although lately it could be a metric
thread into which the air line fitting is
connected.
Air flows through the inlet. The cap is
plumbed internally to force the air to
flow downwards and spiral into the
filter bowl. This creates a cyclonic
action in the compressed air stream to
throw free water and debris that may
be in the air stream against the walls
of the bowl, where it will flow down
into the bottom.
2) The Filter Cap
The filter cap may be composite
plastic or of metal construction
depending on the manufacturer.
Satisfactory compressed air filter
operation depends on the air flowing
through the filter cap in the correct
direction from the supply line out the
filter discharge.
The correct air flow direction will
usually be identified on the cap of the
compressed air filter, by an arrow.
The arrow points in the desired
direction of air flow from the supply
line to the filter discharge. The air
filter will not work properly if you
inadvertently reverse the air flow by
installing the filter backwards.
3) The Air Path
The dotted line depicts the flight path
of the compressed air as flows toward
the filter discharge. In order to exit
the filter through this path, the
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Compressed Air Filters
compressed air must have undergone
the cyclonic action phase, and then
passed through the filter element,
further purifying the airstream.
Resources:
4) Filter Discharge
This is the filter discharge allowing the
flow of the filtered compressed air
from the air filter and down the air
line to your applications.
The fitting size of the discharge port
will usually be the same as the inlet
port. Some compressed air filter
manufacturers offer adapters to allow
you to change the port and fitting size
to one that best suits your application.
In order to reduce inventory of spare
parts, some companies will keep a
standard 3/8" NPT filter as their base
unit, and add adapters to the inlet /
outlet ports to fit them to the smaller
NPT sizes.
While it is feasible to use a larger filter
unit on the small air line, attempting
the reverse may impede compressed
air flow. Do not do this unless you
have checked to ensure that the flow
of the smaller air filter has sufficient
capacity for your application.
This will be a choke point if you under
size the air filter.
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Compressed Air Filters
5) Filter Element
This is the filter element. Insufficient
air supply problems encountered
downstream from your compressed
air filter are often caused by the
element becoming plugged and
choking your air supply. If your air
tool or applications isn't getting
enough air, check the element. Clean
it or replace it, depending on the type.
Some
manufacturers
offer a
Delta P
gauge
as part
of their
filter
assembly.
The
Delta P
will
indicate pressure drop across the
filter, and by extension - the filter
element .
Increasing pressure drop on the
gauge indicates that the filter element
is doing its job, it is trapping debris
and removing it from the compressed
air stream, and getting plugged up in
the process. The dirtier your air, the
sooner your filter elements will plug.
Filter elements have a specific flow
capacity measured in CFM (cubic feet
per minute), and a particulate size
rating measured in Microns.
Microns
The chart below tells you the actual
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Compressed Air Filters
size particle that a specific Micron
rating represents.
General purpose filter elements are 30
or 40 Micron sized. For some
applications, you might need a finer
filtration, and opt for a 5 Micron
element. Depending on your air
quality, a 5 Micron particulate size
element might clog too quickly. Use a
general purpose filter upstream from
the filter with the 5 Micron element,
to increase the finer element filtering
capacity.
So too, when your air filtration
requirements dictate a move into
even finer air filter elements such as a
coalescing filter type. You will
definitely want to have a general
purpose first, then a 5 Micron unit to
further rid the air of particulates
before the air stream reaches the
coalescing filter element.
Here's more information about
compressed air filters.
and...
Here is where you can ask questions
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Compressed Air Filters
about compressed air filters.
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