Purification of air we breathe carries
contaminants. Airborne particles, water, microbes, and chemical
gases enter compressors. At a state these contaminants become
concentrated and more destructive.
Browse our selection of filters to find the right
filtration element for
your compressed air system.
In the compressed air system, hard
particles assault equipment and piping. The result is damage to the
system and more particles generated. Examples of particles found in
a compressed air system include scale, metal oxides, and dirt.
Particles in a compressed air system can:
- Plug orifices of sensitive pneumatic
- Wear out seals
- Erode system components
- Decrease air tool efficiency
- Damage finished products
Particulate compressed air system.
aerosol and concentration. Compressed air is saturated with water.
Since the compressed air is heated during the compression
aftercooler is then used to remove the heat of compression. During
this stage a significant quantity of liquid at compressor
delivering 100 scfm (2.8 m3/hr) at 100 psig (7 bar) and 100ºF
(38ºC) can produce 18 gallons (68 liters) of water a day. These
liquids, if not removed, will cause erosion, damage to pneumatic
equipment and instruments.
Chemical gases, either alone or in
combination with other contaminants, may cause additional damage or
create a potential hazard to the process or personnel. Chemical
gases found in compressed air systems include:
- Carbon dioxide
- Carbon monoxide
Molds, fungus, and compressed air
system. Microbes require moisture to grow. In addition to being a
health threat to workers, microbes produce acidic waste. This waste
corrodes the sludge. Sludge clogs pipes and valves causing valves
to jam (stiction). Filtering and drying processes remove particles,
moisture, microbes, and chemicals from compressed air. Clean, dry
air protects the air system, reduces maintenance costs and
increases finished product yields
of compressed air filters
The first line of defense is the intake air contaminant load
protecting the solids. Generally, these are efficiency filtration.
Over 80% of the contaminants challenging an particulate
contaminants down to 0.3 um and to remove chemical
Oil injected rotary screw compressors have an air/oil separator.
Generally, these separators are 3µm cartridge style compressed air
filters. The air/oil separator allows compressed air to continue
lubricant to the compressor's Coalescer Filter
A coarse coalescing (fig. F1-1) filter separates
large water and oil droplets from the compressed air stream before
the coalescing filter. The coarse coalescer also removes large
solids. Typically, the coarse coalescer is a 3µm coalescer. By
using staged coalescing filtration cost. A coarse coalescer air
systems utilize it.
A high oil compressed air coalescers are rated at a
particulate contamination through direct interception. Its main
function is to remove water and oil aerosols by coalescing the
aerosols into droplets. This happens partially because of torturous
path and pressure drop. Coalescers remove both water and oil
aerosols from the air stream.
It is important to realize that a
coalescer is excellent at removing aerosols and liquids but not
vapors. Vapors are organics like vapor filter removes vapors with
Located desiccant dryer, a particulate compressed
air filter typically 1 to 3µm stops desiccant scale, metal oxides,
and desiccant particles.
Temperature spikes are common downstream of
a heated desiccant dryer. Spikes happen when a regenerated tower
comes back online. The heat generated during temperature of a
particulate compressed air filter and temperature filter protects
against this risk of fire. A particulate compressed air filter
operates at 100°F (38°C) and has a maximum temperature of 150°F
(66°C). A high temperature particulate filter can operate daily at
350°F (177°C) and has a maximum operating temperature of 450°F
(232°C). The level of protection with a high temperature housing is
Vapor Filter (Charcoal
A air stream. Organics, like tastes and odors need
to be removed from hydrocarbons and other organic chemical vapors
from the air system. Depending on the airflow, vapor filters need
to be replaced every few months because the effectiveness of the
compressed air. Compressed air contaminants could destroy product
batches worth millions of dollars in either industry. To protect
these critical processes from contamination, absolute rated
validated final compressed air filters are used. The filter is
located as close to the pneumatic application as practical to
minimize pipe downstream of the final compressed air filter.
A validated filter has a serial number
that allows the tracking of components used to manufacture the
filter. Additionally, the manufacturer has to add quality steps to
the manufacturing cartridge filter is used as a final filter for
compressed air. These filters have double o-rings at the bottom and
a bomb fin top with locking tabs to eliminate the risk of assembly.
A membrane is used as the filter media.
Particles traveling in a fluid have a mass and velocity. The fluid
will follow the path of least resistance. Some particles will
impact onto the filter medium and be caught due to their inertia
driving them into the filter. This is not a primary mechanism for
particle retention. It is more common in gas streams.
Extremely small particles will bounce around randomly in a gas
stream as they strike liquid or gas molecules. This motion is
called Brownian Motion and is more pronounced in gases. The random
path of the particle increases the chance it will strike the
compressed air filter and be captured.
If the particle is larger than the pore of the filter, it is
retained. For example, the screen on your screen door is mesh. It
allows air to pass but keeps insects and anything larger than the
mesh out. Compressed air filters work in the same way; however, the
flow path is not necessarily straight. The pores can be infinitely
smaller, and there can be layer after layer of media for the
liquid/gas to pass through. Direct interception is the most common
form of retention in both gas and liquid service. Most filters
maximize their direct interception with torturous flow paths, which
increase the filter's retention capability.
Installation and Maintenance
Compressed air filters should be
installed in a level pipeline, mounted vertically, the bowl
downward with one element length clearance for element removal. The
filter should be installed at the highest pressure point available,
and as close to the equipment being protected as possible and have
a drip leg immediately upstream.
Pressure drop is used to determine
when to change a filter. Contaminants, pressure, temperature and
other variables affect the service-life of a filter. Generally in a
compressed air system, when the pressure drop across the filter
reaches 8 to 10 psid, a filter should be changed. It is critical to
drain the filter housing daily to release condensate that gathers
in the bottom of the filter bowl. Automatic drain valves simplify
this process and protect your system from water re-entrainment
Inlet Flow and Inlet/Outlet
The compressed air filter has to be rated for the inlet
flow. Inlet flow is generally measured in scfm. Locate the filter
at the highest pressure point available that offers an acceptable
temperature. Match the inlet and outlet pipe size of the filter
assembly to avoid generating excessive pressure drop across the
compressed air filter.
Filters have a maximum operating temperature. General use
compressed air filters are designed for use at 100°F (38°C). It is
a best practice to locate compressed air filters where the
temperature is the lowest possible. There are filters designed to
operate at high temperatures. For example, high temperature
particulate filters. High temperature operation increases the rate
of corrosion and can reduce the life of compressed air filters and
other system components.
The filter housing and filter itself create some resistance to the
flow of the compressed air. There is a pressure drop between the
upstream and downstream sides of a filter. This is called Delta P.
When you size a new compressed air filter and housing, you want a
Delta P that is as low as possible. This is because the life of
your filter is related to its Delta P. For 80% of a typical filters
service-life pressure drop will stay approximately the same. Over
the last 20% of the filter's service-life the delta P rises. There
is a point of diminishing returns. The filter plugs to the point
where air pressure loss is too great. If a compressed air filter is
not changed pressure will continue to build until a terminal Delta
P is reached and the filter collapses. Delta P monitors are
standard on most compressed air filters. Delta P monitors allow you
to watch the filter's pressure. Some have alarms when change-out
Delta P is reached.
of Filter Pressure Drop
Size your filters with the smallest
pressure drop practical. The cost of pressure drop often exceeds
the initial savings of a smaller filter housing. This annual cost
of pressure drop chart (fig. F1-3) illustrates the cost of pressure
Filter Pressure Drop
Manufacturers have started to incorporate microprocessor controls
into compressed air filter design. Traditional gauges indicate when
to change a filter by a pressure or by a color indicator.
Microprocessor controls monitor the filter's condition considering
the hours of operation, cost of compressed air, cost of the filter,
and filter pressure to determine the most cost effective point to
change the filter. Microprocessor controls reduce compressed air
utilities costs by reducing how long a compressed air filter stays
online creating excessive pressure drop.
Several types of microprocessor filter
controls are available. Some models calculate the most economical
time to change a filter based on the cost of compressed air versus
the cost of the filter element. Other microprocessor control
- Time monitoring
- Pressure differential monitoring
- Filter performance monitoring
In addition, remote monitoring
capabilities are available. These units use the latest,
state-of-the-art technology to provide quality air with substantial
Browse our selection of
filters to find the right filtration element for your
compressed air system.