:: Air Compressor Parts ::

If you are one of the many folks that have purchased or are considering purchasing a home compressor, you do want to have a bit of information about compressed air filters.

Compressing air generates a reservoir (receiver / air tank) full of wet, dirty, hot compressed air.

As the air leaves the tank, it carries the crud and free water along with it. It also carries a great deal of water vapour. As the compressed air travels to your appliance (air drill / air grinder / blow gun / air brush - what have you?) the compressed air in the air line cools, and some of the water vapour will condense into free water.

That’s why just having a small compressed air filter at the discharge of the compressor tank may not be enough. Even though the unit at the compressor will take much of the debris and free water from the air there, it can’t remove the vapour. Even though you think your air is being filtered, by the time the air gets to your application, water may flowing out of the exhaust ports and onto your work piece, along with the used compressed air.

Of course, if water flowing or blowing onto your work bothers you just a tad :~} , you’ll want to add another compressed air filter just before you use the air.

Many standard compressed air filters have 5 micron filter elements. If you want to know how big that is, check out the details in the Filter page on my web site.

You can purchase compressed air filters with much finer elements, and you can purchase elements that are coarser, allowing much larger particulates through. Much larger is a relative term. We’re still dealing with pretty small bits here.

If you decide that your application needs extensive air filtration, get a micro-filter element for the additional air filter you will need. The new one might filter particulates down to .005 micron, and if you don’t have a 5 micron unit upstream from it to take out the larger bits, the finer element will plug up really quickly, which is why you’ll need the additional filter housing.

You can purchase compressed air filter elements that will strip oil from the compressed air, these known as coalescent filters. Some piston / reciprocating, and other types of compressors too, let oil “blow by” the piston seals into the compressed air tank, and this oil will get blown downstream as you use compressed air. Compressor oil is not good for most tools that have Buna-N type seals. The compressor lubricating oil might ‘eat’ the seals.

Each compressed air filter you install has a negative affect on the available air pressure at your tool. Pressure drop is a reality in compressed air plumbing. You could supply compressed air at 100 PSI into the discharge air line from your tank, and by the time it gets to your tool, all you have available might be 85 PSI. The flow of compressed air through the air lines, the elbows, the ‘T’s and yes, the air filters, all create pressure drop.

If you are using your compressor a lot (make sure you know it’s duty cycle so that you don’t burn it out) then it would be beneficial to have an auto-drain of some sort on the air filter. A float type will open up and let water and crud flow out when the water in the bowl gets to a certain level. An electric auto-drain will be plugged into a 120 Volt outlet, and will open the bowl drain at preset intervals for a preset length of time. You set the electric auto-drain to the interval necessary to keep the filter bowl fairly empty.

If the water and debris in the filter bowl gets above a certain level in the bowl of the filter, it floods the element, and now your compressed air supply is pumping water and debris through the element downstream to your tool.

Did you know that water rusts metal air tool innards, and that water droplets on your work piece will not allow the beautiful paint job you are air brushing on to it to adhere? Of course you did! That’s why you need a compressed air filter.

One more thing. If your air consumption is great enough then even a filter at your tool may not stop the water vapour streaming along with your compressed air from condensing onto your work piece or in your air tool as the air cools. If that is a problem for you, you will need an air line dryer.

Drop me a email from my site if you have any questions. I’ll be happy to respond.

Bill Wade’s experience in compressed air and other industries spans decades; from field sales positions through to the corporate presidential office. His sales agency represents a select group of industrial firms. Mr. Wade writes about all facets of compressed air at http://www.about-air-compressors.com.

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Recently, I published an article on this site titled: What’s a 2/2 compressed air valve? Here, in the next installment in this series, is information on a slightly more complex air valve; the 3/2 style.

The first number in the 3/2 air valve, the three, refers to the number of “working” air ports that are found in the valve body. That is, the number of ports that supply air to the valve, and channel the compressed air to whatever it is that the valve is supposed to do.

Most 3/2 valves will have numbers or letters etched, cast or painted near each of their three “working” air ports. If there are numbers near the ports, the number 1 would be the supply port to bring the compressed air to that valve.

Port number 2 would be the working port from which air would flow to accomplish whatever task that you wanted that valve to do.

The third port in a 3/2 air valve is an “exhaust” port and if numbered, it could be a 3 or a 5. If the port designations in a 3/2 valve are letters, then port ‘A’ would be the supply port and port ‘B’ the working port, with the third port normally being an ‘E’.

As in the 2/2 valve there may be one or two additional ports in the ends of the 3/2 valve to allow an air signal line or lines to be connected. If this is the case, this 3/2 valve will either be single, or double air piloted.

The 2 in a 3/2 air valve indicates the number of positions that the internal valve mechanism has. In this case, two. When this valve is operated or actuated, it will either open or close and air will either flow to the application upon actuation, or it will be prevented from flowing.

Most 3/2 compressed air valves will be NC, or normally closed. When the valve is not actuated, it’s normal state is closed, and compressed air cannot pass through it.

If your application calls for air to flow through the valve when it’s not actuated, that the circuit needs air to be flowing through this valve when it is at rest, then a NO or normally open configured valve would be selected.

All 3/2 valves have actuators that will operate or ’shift’ the air valve. An external button, or toggle, or perhaps a solenoid actuator would be the visible actuator. Inside, there will likely be an internal actuator - a spring - which will shift the valve to the off position when the external actuator is not being used.

If the external actuator is ‘detented’, then when the valve is operated, it will stay in it’s last selected position until an operator changes it. Detented means it will stay where it’s put! This is useful when an operator needs to actuate the valve, and then manually perform another operation while the air valve feeds air to the application.

Unlike it’s less complex 2/2 valve cousin, the 3/2 valve is used when a compressed air supply is needed to an application or device that uses compressed air to power it, yet in itself has no integral air pathway to atmosphere. Therefore, when the device has performed it’s function, and it’s time to ‘deflate’ it or to let the compressed air back out, the third port in the 3/2 valve comes into play.

When the compressed air supply through the valve is shut off internally, a pathway back through the valve to atmosphere will be opened, to allow the compressed air to escape. The air supply is shut, so the compressed air flowing to the valve cannot flow through it, and the compressed air that was formerly in the device or application can now bleed back down the air line through the valve to exhaust.

So, what type of devices are these?

Usually they are single acting type actuators. One comes to mind immediately; “Air springs”.

Both Firestone and Goodyear (among others) manufacture “air springs”. These are devices that look like tires, but rather than have an opening in the middle of the doughnut where the rim goes, they are closed on both sides with steel plates. In one side there will be an air port to which an air line from a 3/2 valve can be connected. These “air springs” are mounted on their sides, picture a tire lying flat after you’ve taken it off your car, and can generate huge actuation forces. Force equals pressure times area, and the “piston” size inside an air spring can be huge. The application of air springs mirrors that of typical air cylinders, yet offer large capacity at a fraction of the cost of an air cylinder of a necessary size to generate the same force as the air spring.

Another application for 3/2 valves is single acting air cylinders. Whether they are spring extend or spring retract, an air supply is required to operate the SA cylinder. A 3/2 valve is designed to do just that.

A couple of more points; the 3/2 valve can have the exhaust port plugged, and voila, you have a 2/2 valve.

If the cost of the valve is the same, you can use a 3/2 air valve anywhere you might use a 2/2 valve. Since 2/2 valves always have to have the “working port” ultimately plumbed to atmosphere, that there is an exhaust port in a 3/2 valve offers no obstacle to it’s use.

If you have a double acting air cylinder, and you don’t have a 4/2 or 5/2 (more on these valves next article) available, you can use two 3/2 valves to operate any cylinder that requires two supply lines in order for it to extend and retract.

At ABOUT-air-compressors.com my e-book entitled All About Air Valves - Volume One is now available. If you are interested in more information about air valves, do visit the site and download a copy. This first e-book is an introduction to air valves, and focuses on the 2/2 iteration. Future volumes will focus on 3/2 valves, and then the 4/2 & 5/2 configurations.

And as always, if you have any questions, please send me a message from the contact screen at my web site.

Bill Wade’s experience in compressed air and other industries spans decades; from field sales positions through to the corporate presidential office. His sales agency represents a select group of industrial firms. Mr. Wade writes about all facets of compressed air at http://www.about-air-compressors.com

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The air filter in an air conditioning system keeps the cooling coils and air inside the room clean and free from all pollutants, pet dander, ozone emissions and airborne particles.

There are many different kinds of air filters available today, such as HEPA, standard, pleated, electrostatic and electronic filters. Of these, standard, pleated and electrostatic filters are the most common types of filters that are used in air conditioners. Generally these filters are located in walls, ceilings, furnaces, or in the air conditioner itself.

Standard Air Filters, having the capacity of removing 10 percent of the airborne pollutants, are made of spun fiberglass with cardboard frames. . They should be changed once a month.
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Pleated Air Filters catch around 35% to 40% of the particles in the air. Owing to their greater surface area with filter material folded back and forth like a paper fan, manufacturers claim that they can last from two to four months. The cost of these filters ranges from $5 to $20 which is slightly more than that of standard filters.

Electrostatic filters use filter media, which use an electric charge to attract the dirt particles in the air. These filters may have electric charge built-in, or else the air moving through the layers of the system creates electric charge. They may cost from around $20 to over $100 each. These filters only need to be changed once a year.

Sometimes people with allergies may consider the usage of an electronic air cleaner in the air conditioner, which works on the same principle as that of electrostatic filter. However, it is far more effective than electrostatic filter and does not hinder the flow of air inside the air conditioning system. Whatever type of air conditioner filter you use, it is advisable to check the cleanliness of the coils of the filter by a contractor at least once in a month.

Perhaps the most important measure that will ensure the efficiency of an air conditioner is frequent replace of its filters. One should change the air conditioner’s filter regularly, as clogged, dirty filters block normal air flow and reduce the system’s efficiency significantly by impairing the coils’ heat-absorbing capacity.

Air Filters Info provides detailed information on home, car, electronic, and HEPA air filters, as well as air conditioner filters and air filter manufacturers. Air Filters Info is the sister site of Air Purifiers Web.

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