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Plasma cutting is an industrial process that makes use of superheated ionized gas to cut metal pieces. Compressed gas is the key component of this process. This gas is in most cases the very same air that you breathe, which is roughly about 1 part oxygen and 4 parts nitrogen. There’s really nothing special about this safe, nonflammable gas mixture except for the fact that it’s compressed from normal atmospheric pressure (14.7 psi) to around 90-135 psi. This compressed air is then heated by electricity to temperatures up to 40,000ºF. These extremely high temperatures rip electrons from gas molecules, so you now have ionized gas, which science geeks call plasma.
When blasted through a focused nozzle, plasma can cut through materials. This high-speed plasma doesn’t only cut through the workpiece but also blows molten material away. Pretty cool, right? The thing about this process is it comes with some drawbacks, particularly due to the air fed into the cutter when it’s unfiltered.
Dangers of Unfiltered Compressed Air for Plasma Cutting
Your plasma torch is susceptible to a few factors, but air quality is one of the major plasma cutting concerns. Before we dive in deeper, let’s talk about the anatomy of a typical motor-driven plasma cutter. In this system, you have a compressor and an air storage tank or receiver. The compressor sucks in the surrounding air and feeds it into a pump, which then delivers the air into a receiver, where it is compressed.
The problem is, air hardly ever comes pure. In virtually all places in the world, the air contains much moisture and other particulates. If you compress a cubic meter of air, all of the moisture in this volume of air is stored in the receiver as well. This compressed air travels through the pipes and cools down enough to allow moisture to condense into droplets.
More moisture condenses when the air blasts through the plasma torch, where air rapidly depressurizes and cools down. In fact, you may actually see some mist coming out of the torch head on a humid day if your compressed air system has no air dryer or filter (1).
Key Benefits of an Air Dryer
An air dryer, as its name implies, dries the air that the compressor feeds into the plasma cutter. Most of these filters remove not just humidity but also oil and other contaminants that may reduce the lifespan of your tool and sabotage the quality of your cuts. The filter is usually installed between your compressor and plasma cutter. If you’re a technician who uses a plasma cutter often, you’ll realize that an air dryer filter maximizes the longevity of your consumables, reducing the need for replacement or repair.
If you’re wondering whether or not you should buy an air dryer filter, ask yourself if you’re using your plasma cutter longer than 10 hours a year. If you are, then installing a filter makes sense, especially if you’re using premium machines. Note that consumables for machines like Hypertherm cost at least $100. In contrast, an air dryer that can last for a year costs about $80.
Also, if you want cleaner cuts, you’re better off investing in an air dryer filter.
Best Air Dryer Filters for Plasma Cutters
Motor Guard M30
Motor Guard is famous among plasma cutter owners not only because it’s inexpensive but also because it’s easy to install and maintain. If you’re looking for air compressor dryer that does the job, this should be on your list.
Any Motor Guard filter has a maximum pressure of 125 psi and can remove unwanted moisture effectively. The M30 features a single replacement cartridge that keeps not only humidity but also oil and other stuff from gaining access to the air line. Maintenance usually just involves replacing the cartridge.
Hypertherm Powermax 45
The Powermax 45 is known for its performance and durability. That’s why it’s popular in the metal fabrication industry. Any metal fabrication technician knows the name Hypertherm. The flagship model comes with a 10-foot power cord and 20-foot long torch cord. This beast can do drag cutting, mechanized cutting, fine feature cutting, precision gouging, among other things. With three torch options (45 degree, 90 degree, and straight torch), you don’t have to buy separate units for certain work pieces. This extraordinary machine, however, is quite pricey.
Ingersoll Rand Refrigerated Dryer
Probably the most commonly seen type of compressed air dryer, refrigerated dryers cool the warm, humid air to about 3 degrees Celsius. All the moisture in the air condenses and is then eliminated. This type of air dryer is suitable for large scale productions.
The Ingersoll Rand Dryer in particular withstands long periods of use, hence earning a notable reputation among refrigerated dryers because of its durability. It is also suitable with CNC plasma cutting systems.
Compressed air for plasma cutting comes with moisture and other impurities that can damage your equipment in the long run and reduce the quality of your work. Hence, it makes sense to have a compressed air dryer filter for your plasma cutter. An air dryer improves cutting efficiency and lengthens the lifespan of your consumables.
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