Tag: coalescing

Why – And Where – Do You Need Filtration In Your Compressed Air System?

Published on by Russ BowmanLeave a comment

Good engineering practice, and proper system design, call for filters at various points in a compressed air system. I’m going to go through these along the path that compressed air follows, from being drawn from atmospheric pressure in to the compressor, to being returned to atmospheric pressure at its point of use.

Any air compressor is going to have an intake filter. The small “pancake” compressor in my garage has a little disc looking thing with a screen whose mesh is about the same as my house’s window screens. Larger industrial air compressors have cartridge-type filters that impart a spiral motion to the incoming air. That motion actually removes most of the incoming particulate, while the rest gets caught in the pleats of the fiber element. The main purpose for an intake filter is to protect the compressor’s internal components. Solid particulates can really do a number on the high speed, close tolerance moving parts inside a compressor, in a hurry.

All the other filters you might find are there to ensure proper operation of the rest of your compressed air system:

  • Distribution. No intake filter is going to be 100% efficient, nor will it remove especially fine particulate that doesn’t present a real risk of damage or wear to the compressor. Intake filters also will not remove oil (or oil vapor) and water (or water vapor). The compressor itself can actually add contaminants to the compressed air, in the form of wear particles (remember those close tolerance moving parts I mentioned above?) and oil carryover. All of these contaminants will, however, be detrimental to the pipe & fittings that takes the newly compressed air to where it’s used. They can cause a buildup on the inner walls of the piping that inhibits flow. Water causes the pipe to start rusting from the inside out. When that rust scale breaks loose, it can clog, foul, or damage valves, fittings, and other control devices in the distribution header. Ideally, you’ll use filtration with a particulate element, a centrifugal element for water, and a coalescing element for oil/oil vapor (if needed…this isn’t a concern for oil-free compressors, for example).
  • Distribution, part 2. If your facility is large enough, you may need filtration at strategic locations…perhaps one for the air going to the machine shop, another for an area with machinery equipped with pneumatic cylinders, another for an assembly area where pneumatic tools are used, etc. The type(s) of filter(s) you use at those points will be determined by what the air is used for. If you know you have oil carryover from your compressor, you probably want a coalescing filter on the line to Safety Air Guns that blow off parts before painting. You don’t need them on lines going to your pneumatic tools, though…that carryover will likely help supplement the point-of-use lubricators that they use.
  • Point-of-use. Good engineering practice calls for a final stage of filtration, located as close as practical to the air operated device(s). EXAIR includes a Filter Separator with a 5 micron particulate element and a centrifugal element for water with all of our product Kits. Oil Removal Filters are also available for oil/oil vapor. They also provide additional particulate filtration to 0.03 microns.
EXAIR offers a variety of Filter Separators (left), Oil Removal Filters (middle), and Pressure Regulators (right) that are suitable for a wide range of point-of-use compressed air applications. Contact an Application Engineer for more details.

At EXAIR, we’re here to make sure you get the most out of your compressed air system. If you’d like to find out more about filtration…or any other aspect of air treatment (drying, regulating, cooling, etc.)…give me a call.

Russ Bowman, CCASS

Application Engineer
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Removing Oil From Your Compressed Air Helps Keep Your EXAIR Products Running Maintenance-Free

Published on by Tyler DanielLeave a comment

Most of EXAIR’s line of Intelligent Compressed Air Products have no moving parts and require no maintenance. The caveat to the “no maintenance” aspect is proper filtration at the point of use. Many products air demand products like nozzles, air knives and air amplifiers have very tight orifices that could get clogged from any contaminants such as particulate, condensate, and lubricant. Oil and dirt could build up inside of any of these products and keep them from working properly. EXAIR recommends point of use filtration to be installed just upstream of any EXAIR product for this purpose.

Oil is commonly present in a compressed air supply, whether that’s intentional or not can vary. Many air compressors are oil lubricated by a constant supply of oil, inevitably some of this oil ends up in the air supply. As the piston rings wear, more oil is permitted to pass by and ends up in the distribution system. While this is kept to a minimum with proper maintenance, it is impossible to prevent unless using an oil-free compressor.

Sometimes oil is present in the air supply intentionally, many pneumatic devices require a precise amount of oil to keep the internal moving parts lubricated. In the case of any EXAIR Intelligent Compressed Air Product, we recommend particulate free, condensate free, and oil free air.

In order to remove oil from the air supply, EXAIR offers a line of Oil Removal Filters. These coalescing style filters are used to remove very fine water vapor as well as any residual oil. These filters are highly recommended to be installed just prior to any dryer that contains a media that would be compromised by any lubricant passing through it. Coalescing filters utilize an element typically made up of glass fibers that “coalesce”, or combine, the fine water vapor and oil aerosols until the droplet size becomes large enough that it drops off into the bowl or filter housing. With a coalescing filter, the most common cause of pressure drop increase is due to particulate clogging the filter element. Because of this, a particulate filter should always be installed just prior to any coalescing filters.

Without any filtration, any oil in the air supply will pass through the point of use device and into or on to your product or process. With the elimination of this problem such a simple solution, don’t neglect proper air preparation to ensure you’re delivering clean, oil-free air to all of your Intelligent Compressed Air Products.

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD

Compressed Air System Equipment – What You Need To Know

Published on by Russ BowmanLeave a comment

The use of compressed air in industry is so widespread that it’s long been called “the fourth utility” (along with electricity, water, and natural gas). As a function of energy consumption (running an air compressor) to energy generated (operation of pneumatic equipment), only 10-15% of the energy consumed is converted to usable energy stored as compressed air. Its “bang for the buck”, however, comes when you consider the total cost of ownership – yes, it costs a lot to generate, but:

  • It’s relatively safe, when compared to the risks of electrocution, combustion, and explosion associated with electricity & natural gas.
  • Air operated tools, equipment, and products are generally much cheaper than their electric, gas, or hydraulic powered counterparts.
  • Air operated products, like anything, require periodic maintenance, but oftentimes, that maintenance simply comes down to keeping the air supply clean and moisture free, unlike the extensive (and expensive) maintenance requirements of other industrial machinery.

Even with these advantages, though, it’s still critical to get all you can out of that 10-15% of the energy you’re consuming to make that compressed air, and that starts with having the right stuff in the right place. Now, all of the following “stuff” might not apply to every compressed air system. I once worked in a repair shop, for example, with a small compressor that was used for a couple of blow off guns, impact drivers, and a sidearm grinder. I’ve also done field service in facilities with hundreds of pneumatic cylinders & air motors that operated their machinery. Those places had even more “stuff” than I’m devoting space to in this blog, but here’s a list of the “usual suspects” that you’ll encounter in a properly designed compressed air system:

  • Air compressor. I mean, of course you need a compressor, but the size and type will be determined by how you’re going to use your air. The small repair shop I worked in had a 5HP reciprocating positive displacement compressor with a 50 gallon tank, and that was fine. The larger facilities I visited often had several 100 + HP dynamic centrifugal or axial compressors, which get more efficient with size.
  • Air preparation. This includes a number of components that can be used to cool, clean, and dry the air your compressor is generating:
    • Pressurizing a gas raises its temperature as well. Hot compressed air could cause unsafe surface temperatures and can damage gaskets, seals, and other components in the system. Smaller compressors might not have this problem, as the heat of compression is often dissipated through the wall of the receiver tank and the piping at a rate sufficient to keep the relatively low (and often intermittent) flow at a reasonable temperature. Larger compressors usually come with an aftercooler.
    • The air you compress likely has a certain amount of moisture in it…after nitrogen and oxygen, water vapor usually makes up more of the content of atmospheric air than all other trace gases combined. There are a number of air dryer types; selection will be dictated by the specifics of your facility.
    • Your air is going to have other contaminants in it too. We did welding & grinding in the repair shop where our compressor sat in the corner. We kept a few spare intake filters handy, and replaced them regularly. In conjunction with the aftercooler & dryer, larger industrial compressors will also have particulate filters for these solids. For extra protection, coalescing filters for oil vapor, and adsorption filters for other gases & liquid vapors, are specified.
  • Distribution. In the repair shop, we had a 3/4″ black iron pipe that ran across the ceiling, with a few tees & piping that brought the air down to the individual stations where we used it. The larger facilities I visited had larger variations of this “trunk and branch” type network, and some were even big enough to make use of a loop layout…these were especially popular when multiple air compressors were located throughout the facility. In addition to black iron, copper & aluminum pipe (but NEVER PVC) are commonly used too.
  • Condensate removal. The small repair shop compressor had a valve on the bottom of the tank with a small hose that we’d blow down into a plastic jug periodically. Larger systems will have more complex, and oftentimes automated condensate management systems.

So, that’s the system-wide “stuff” you’ll usually encounter in a properly designed compressed air system. After that, we’ll find a number of point-of-use components:

  • Air preparation, part 2. The compressor intake & discharge filtration mentioned above make sure that you’re putting clean air in the distribution piping. That’s fine if your distribution piping is corrosion resistant, like aluminum or copper, but black iron WILL corrode, and that’s why you need point-of-use filters. EXAIR Automatic Drain Filter Separators have 5 micron particulate elements, and centrifugal elements that ‘spin’ any moisture out. If oil is an issue, our Oil Removal Filters have coalescing elements for oil/oil vapor removal, and they provide additional particulate protection to 0.03 microns.
  • Pressure control. Your compressor’s discharge pressure needs to be high enough to operate your pneumatic device(s) with the highest pressure demand. Odds are, though, that not everything in your plant needs to be operated at that pressure. EXAIR Pressure Regulators are a quick & easy way to ‘dial in’ the precise supply pressure needed for specific products so they can get the job done, without wasting compressed air.
  • Storage. This could also be considered system “stuff”, but I’m including it under point-of-use because that’s oftentimes the reason for intermediate storage. Having a ready supply of compressed air near an intermittent and/or large consumption device can ensure proper operation of that device, as well as others in the system that might be “robbed” when that device is actuated. They’re good for the system, too, as they can eliminate the need for higher header pressures, which cause higher operating costs, and increased potential for leaks. EXAIR Model 9500-60 60 Gallon Receiver Tanks are an ideal solution for these situations.

For more information on proper installation and use of compressed air system “stuff” like this, the Compressed Air & Gas Institute’s Compressed Air and Gas Handbook has a good deal of detailed information. The Air Data section of EXAIR’s own Knowledge Base is a great resource as well.

Of course, all the attention you can pay to efficiency on the supply side doesn’t matter near as much if you’re not paying attention to HOW you’re using your compressed air. EXAIR Intelligent Compressed Air Products are designed with efficiency, safety, and noise reduction in mind. Among the other ways my fellow Application Engineers and I can help you get the most out of your compressed air system, we’re also here to make sure you get the right products for your job. To find out more, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Compressed Air Quality Classes – ISO 8573-1

Published on by Jordan T ShouseLeave a comment

ISO 8573-1:2010 is the international standard for Air Quality Classes. It lays the ground rules for acceptable levels of pollutants, particulate, moisture, and oil in a compressed air source. 

Image Courtesy of  the Compressed Air Challenge

Though the standard has detailed standards for maximum particle size, maximum pressure dew point and maximum oil content for different industries and/or environments (see Slide show above) we can generalize a bit and express the levels of air quality like this:

Plant Air – general plant compressed air used for air tools, nozzles etc.
Instrument Air – found in laboratories, paint and powder coat booths, used for climate control.
Process Air – used in food and pharmaceutical applications, electronics applications.
Breathing Air – used for breathing respirators, breathing tanks and hospital air systems.

Achieving the different levels of air quality can be done with 3 basic types of filtration.
     1. Particulate – a filter element removes particles larger than the opening in the filter material. Typically done with particles greater than 1 micron.
     2. Coalescing – use different methods to capture the particles; 1) direct interception – works like a sieve, 2) Inertial impaction – collision with filter media fibers, 3) Diffusion – particles travel in a spiral motion and are captured in the filter media.
     3. Adsorption – the filter element holds the contaminants by molecular adhesion.

Filters
EXAIR FILTER SEPARATORS

The higher the class your air needs to be the more of these filtration methods you will use. Adsorption will remove more and finer particles than a simple particulate filter. And many applications will use a combination of these methods.

EXAIR products, all of which need a source of “clean, dry air” will operate very well utilizing a source of plant air and only a particulate filter. Your process, dictate if you need to supply additional filtration methods for better air quality. For example, an automotive plant using compressed air to blow parts off will not need the kind of filtration a food handling facility will need while blowing a food product off. If you are using a lubricated compressor or have lubricant in your compressed air lines from another source, you will want to use a coalescing oil removal filter.

EXAIR stocks 5 micron particulate filters which are properly sized for each individual product as an option for our customers if they choose. We also stock coalescing oil removal filters for customers who may need to remove oil from the air. Replacement filter elements are also available and should be replaced at least twice a year, depending on the quality of your air.

Oil Removal Filter
EXAIR Oil Removal Filter

Remember to ask about filtration if you have any concerns about your air quality. We can assist in sizing up the proper filters to get the air quality we recommend for proper operation and longevity of our products. 

If you would like to see how we might be able to improve your process or provide a solution for valuable savings, please contact one of our Application Engineers.

Jordan Shouse
Application Engineer
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Image Courtesy of  the Compressed Air Challenge