Intelligent Compressed Air: Refrigerant Dryers and How They Work

We’ve seen in recent blogs that Compressed Air Dryers are an important part of a compressed air system, to remove water and moisture to prevent condensation further downstream in the system.  Moisture laden compressed air can cause issues such as increased wear of moving parts due to lubrication removal, formation of rust in piping and equipment, quality defects in painting processes, and frozen pipes in colder climates.  The three main types of dryers are – Refrigerant, Desiccant, and Membrane. For this blog, we will review the basics of the Refrigerant type of dryer.

All atmospheric air that a compressed air system takes in contains water vapor, which is naturally present in the air.  At 75°F and 75% relative humidity, 20 gallons of water will enter a typical 25 hp compressor in a 24 hour period of operation.  When the the air is compressed, the water becomes concentrated and because the air is heated due to the compression, the water remains in vapor form.  Warmer air is able to hold more water vapor, and generally an increase in temperature of 20°F results in a doubling of amount of moisture the air can hold. The problem is that further downstream in the system, the air cools, and the vapor begins to condense into water droplets. To avoid this issue, a dryer is used.

Refrigerated Dryer

Fundamental Schematic of Refrigerant-Type Dryer

Refrigerant Type dryers cool the air to remove the condensed moisture and then the air is reheated and discharged.  When the air leaves the compressor aftercooler and moisture separator (which removes the initial condensed moisture) the air is typically saturated, meaning it cannot hold anymore water vapor.  Any further cooling of the air will cause the moisture to condense and drop out.  The Refrigerant drying process is to cool the air to 35-40°F and then remove the condensed moisture.  The air is then reheated via an air to air heat exchanger (which utilizes the heat of the incoming compressed air) and then discharged.  The dewpoint of the air is 35-40°F which is sufficient for most general industrial plant air applications.  As long as the compressed air stays above the 35-40°F temperature, no further condensation will occur.

The typical advantages of Refrigerated Dryers are-

  1.  – Low initial capital cost
  2.  – Relatively low operating cost
  3.  – Low maintenance costs

If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Intelligent Compressed Air: How to Develop a Pressure Profile

An important part of operating and maintaining a compressed air system is taking accurate pressure measurements at various points in the compressed air distribution system, and establishing a baseline and monitoring with data logging.  A Pressure Profile is a useful tool to understand and analyze the compressed air system and how it is functioning.

Pressure Profile 1

Sample Pressure Profile

The profile is generated by taking pressure measurements at the various key locations in the system.  The graph begins with the compressor and its range of operating pressures, and continues through the system down to the regulated points of use, such as Air Knives or Safety Air Guns.  It is important to take the measurements simultaneously to get the most accurate data, and typically, the most valuable data is collected during peak usage periods.

By reviewing the Pressure Profile, the areas of greatest drop can be determined and the impact on any potential low pressure issues at the point of use.  As the above example shows, to get a reliable 75 PSIG supply pressure for a device or tool, 105-115 PSIG must be generated, (30-40 PSIG above the required point of use pressure.)  As a rule of thumb, for every 10 PSIG of compressed air generation increase the energy costs increase 5-7.5%

By developing a total understanding of the compressed air system, including the use of tools such as the Pressure Profile, steps to best maximize the performance while reducing costs can be performed.

If you have questions about getting the most from your compressed air system, or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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The Importance Of Air Compressor System Maintenance

 

It should go without saying, but proper operation of anything that has moving parts will depend on how well it’s maintained.  Compressed air systems are certainly no exception; in fact; they’re a critical example of the importance of proper maintenance, for two big reasons:

*Cost: compressed air, “the fourth utility,” is expensive to generate.  And it’s more expensive if it’s generated by a system that’s not operating as efficiently as it could.

*Reliability: Many industrial processes rely on clean or clean & dry air, at the right pressure, being readily available:

  • When a CNC machine trips offline in the middle of making a part because it loses air pressure, it has to be reset.  That means time that tight schedules may not afford, and maybe a wasted part.
  • The speed of pneumatic cylinders and tools are proportional to supply pressure.  Lower pressure means processes take longer.  Loss of pressure means they stop.
  • Dirt & debris in the supply lines will clog tight passages in air operated products.  It’ll foul and scratch cylinder bores.  And if you’re blowing off products to clean them, anything in your air flow is going to get on your products too.

Good news is, the preventive maintenance necessary to ensure optimal performance isn’t all that hard to perform.  If you drive a car, you’re already familiar with most of the basics:

*Filtration: air compressors don’t “make” compressed air, they compress air that already exists…this is called the atmosphere, and, technically, your air compressor is drawing from the very bottom of the “ocean” of air that blankets the planet.  Scientifically speaking, it’s filthy down here.  That’s why your compressor has an inlet/intake filter, and this is your first line of defense. If it’s dirty, your compressor is running harder, and costs you more to operate it.  If it’s damaged, you’re not only letting dirt into your system; you’re letting it foul & damage your compressor.  Just like a car’s intake air filter (which I replace every other time I change the oil,) you need to clean or replace your compressor’s intake air filter on a regular basis as well.

*Moisture removal: another common “impurity” here on the floor of the atmospheric “ocean” is water vapor, or humidity.  This causes rust in iron pipe supply lines (which is why we preach the importance of point-of-use filtration) and will also impact the operation of your compressed air tools & products.

  • Most industrial compressed air systems have a dryer to address this…refrigerated and desiccant are the two most popular types.  Refrigerant systems have coils & filters that need to be kept clean, and leaks are bad news not only for the dryer’s operation, but for the environment.  Desiccant systems almost always have some sort of regeneration cycle, but it’ll have to be replaced sooner or later.  Follow the manufacturer’s recommendations on these.
  • Drain traps in your system collect trace amounts of moisture that even the best dryer systems miss.  These are typically float-operated, and work just fine until one sticks open (which…good news…you can usually hear quite well) or sticks closed (which…bad news…won’t make a sound.)  Check these regularly and, in conjunction with your dryers, will keep your air supply dry.

*Lubrication: the number one cause of rotating equipment failure is loss of lubrication.  Don’t let this happen to you:

  • A lot of today’s electric motors have sealed bearings.  If yours has grease fittings, though, use them per the manufacturer’s directions.  Either way, the first symptom of impending bearing failure is heat.  This is a GREAT way to use an infrared heat gun.  You’re still going to have to fix it, but if you know it’s coming, you at least get to say when.
  • Oil-free compressors have been around for years, and are very popular in industries where oil contamination is an unacceptable risk (paint makers, I’m looking at you.)  In oiled compressors, though, the oil not only lubricates the moving parts; it also serves as a seal, and heat removal medium for the compression cycle.  Change the oil as directed, with the exact type of oil the manufacturer calls out.  This is not only key to proper operation, but the validity of your warranty as well.

*Cooling:  the larger the system, the more likely there’s a cooler installed.  For systems with water-cooled heat exchangers, the water quality…and chemistry…is critical.  pH and TDS (Total Dissolved Solids) should be checked regularly to determine if chemical additives, or flushing, are necessary.

*Belts & couplings: these transmit the power of the motor to the compressor, and you will not have compressed air without them, period.  Check their alignment, condition, and tension (belts only) as specified by the manufacturer.  Keeping spares on hand isn’t a bad idea either.

Optimal performance of your compressed air products literally starts with your compressor system.  Proper preventive maintenance is key to maximizing it.  Sooner or later, you’re going to have to shut down any system to replace a moving (or wear) part.  With a sound preventive maintenance plan in place, you have a good chance of getting to say when.

If you’d like to talk about other ways to optimize the performance of your compressed air system,  give me a call.

Russ Bowman
Application Engineer
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Image courtesy of U.S. Naval Forces Central Command/U.S. Fifth Fleet, Creative Commons License 

Compressed Air Filtration – Particulate, Coalescing, and Adsorption Types

Compressed air systems will contain contaminants that can lead to issues and increased costs through contamination of product, damage to the air operated devices, and air line clogging and restriction. Proper air preparation is critical to optimizing performance throughout the plant operations.

Because there are different types of contaminants, including solid particles, liquid water, and vapors of water and oil, there are different methods of filtration, each best suited for maximum efficiency in contaminant removal.

Particulate Filters – The compressed air flows from outside to inside of the filter element. The compressed air first passes through a baffle arrangement which causes centrifugal separation of the largest particles and liquid drops (but not liquid vapors), and then the air passes through the filter element.  The filter element is usually a sintered material such as bronze.  The filter elements are inexpensive and easy to replace. Filtration down to 40-5 micron is possible.

9001

Particulate Type Filter with Sintered Bronze Element

Coalescing Filters – This type operates differently from the particulate type.  The compressed air flows from inside to outside through a coalescing media. The very fine water and oil aerosols come into contact with fibers in the filter media, and as they collect, they coalesce (combine) to form larger droplets towards the outside of the filter element. When the droplet size is enough the drops fall off and collect at the bottom of the filter housing.  The filter element is typically made up of some type glass fibers.  The coalescing filter elements are also relatively inexpensive and easy to replace. Filtration down to 0.01 micron at 99.999% efficiency is possible.

9005

Coalescing Type Filter with Borosilicate Glass Fiber Element

Adsorption Filters – In this type of filtration, activated carbon is typically used, and the finest oil vapors, hydrocarbon residues, and odors can be be removed.  The mechanism of filtration is that the molecules of the gas or liquid adhere to the surface of the activated carbon.  This is usually the final stage of filtration, and is only required for certain applications where the product would be affected such as blow molding or food processing.

When you work with us in selecting an EXAIR product, such as a Super Air Knife, Super Air Amplifier, or Vortex Tube, your application engineer can recommend the appropriate type of filtration needed to keep the EXAIR product operating at maximum efficiency with minimal disruption due to contaminant build up and unnecessary cleaning.

If you have questions regarding compressed air filtration or any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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Consider these Variables When Choosing Compressed Air Pipe Size

Here on the EXAIR blog we discuss pressure drops, correct plumbing, pipe sizing, and friction losses within your piping system from time to time.   We will generally even give recommendations on what size piping to use.  These are the variables that you will want to consider when selecting a piping size that will suit your need and give the ability to expand if needed.

The variables to know for a new piping run are as follows.

  • Flow Rate (SCFM) of demand side (products needing the supplied compressed air)
  • System Pressure (psig) – Safe operating pressure that will account for pressure drops.
  • Minimum Operating Pressure Allowed (psig) – Lowest pressure permitted by any demand side point of use product.
  • Total Length of Piping System (feet)
  • Piping Cost ($)
  • Installation Cost ($)
  • Operational Hours ( hr.)
  • Electical Costs ($/kwh)
  • Project Life (years) – Is there a planned expansion?

An equation can be used to calculate the diameter of pipe required for a known flow rate and allowable pressure drop.   The equation is shown below.

A = (144 x Q x Pa) / (V x 60 x (Pd + Pa)
Where:
A = Cross-Sectional are of the pipe bore. (sq. in.).
Q = Flow rate (cubic ft. / min of free air)
Pa = Prevailing atmospheric absolute pressure (psia)
Pd  = Compressor discharge gauge pressure (psig)
V = Design pipe velocity ( ft/sec)

If all of these variables are not known, there are also reference charts which will eliminate the variables needed to total flow rate required for the system, as well as the total length of the piping. The chart shown below was taken from EXAIR’s Knowledge Base.

Piping

Airflow Through 1/4″ Shed. 40 Pipe

Once the piping size is selected to meet the needs of the system the future potential of expansion should be taken into account and anticipated for.   If no expansion is planned, simply take your length of pipe and start looking at your cost per foot and installation costs.    If expansions are planned and known, consider supplying the equipment now and accounting for it if the additional capital expenditure is acceptable at this point.

The benefits to having properly sized compressed air lines for the entire facility and for the long term expansion goals makes life easier.   When production is increased, or when new machinery is added there is not a need to re-engineer the entire system in order to get enough capacity to that last machine.   If the main compressed air system is undersized then optimal performance for the facility will never be achieved.   By not taking the above variables into consideration or just using what is cheapest is simply setting the system up for failure and inefficiencies.   All of these considerations lead to an optimized compressed air system which leads to a sustainable utility.

Brian Farno
Application Engineer Manager
BrianFarno@EXAIR.com
@EXAIR_BF

Compressed Air Accessories – Filters and Regulators – The Rest of the Solution

IMG_5696

EXAIR Regulator with gauge and Filter/Separator

Many times in the stories that are written in our daily blogs, we espouse the many benefits of installing and using EXAIR made products into our many customers’ compressed air-based applications. From the guy who has a small shop in his home garage using our Atto Super Air Nozzle to much larger applications where customers use our 84” Long Super Air Knives to do such things as drying cast Acrylic Sheets used in tub and shower surrounds, the message is a very consistent one. Customers benefit by saving money, increasing the safety level of an application, reducing sound levels and improving productivity.  There’s no doubt that our customers will excel in these areas.

Knowing there is much more to a compressed air system than just point of use products, lets shed a little light on the other “parts” of a typical system set-up. Those would be the compressed air filter / separators and the pressure regulators that are a highly recommended part of a good installation. But why are they so highly recommended? What exactly is their role and why would anyone want or need to install them?

First, the blunt realities of compressed air and its relative “un-clean” condition once it arrives at the point of use. Since compressed air a utility that is produced in-house, the quality and quantity available will vary widely from facility to facility. And since it is not a regulated utility such as gas or electricity are, there are no universal minimums of quality that compressed air must meet before sent out to the distribution system. Yes, of course, companies are all the time getting better at this part, but many still operate with older, iron pipe systems that produce rust and scale which wreak havoc on the components within mechanical products that use compressed air as their power source. The point is that you are never sure of the quality of the air you will get at the point of use, so install a compressed air filter near that point to keep the debris out of your Air Knife, Nozzle, Line Vac or even other components like solenoid valves, air motors and the like. Believe me when I say it is much easier to un-screw a bowl from a filter housing and change an element than it is to disassemble an air motor or an 84” long Super Air Knife because rust migrated in from the pipes. So it is quite safe to say that an ounce of prevention in this case is worth a pound of cure!

Second, the discussion turns to the Regulator part of the equation. As many know, our products and those of other pneumatic product manufacturers have a certain set of specifications regarding performance at stated input pressures. But what if your application doesn’t require that “full, rated performance”? Maybe instead of needing two pounds of force, you only need one pound? In fact, if you provided two pounds of blowing force, you would end up “over-blowing” your target. By that, I mean you cause damage to the target or other surrounding items in the application. Or, perhaps blowing to hard (or sucking too hard in the case of a Line Vac or E-vac) might cause the vessel or the material you are picking up to collapse or deform (due to too much power).  There is also the concern about using more energy than one really needs to in order to achieve the desired effect in an application. In other words, if you can achieve your goals with only 40 PSIG, then why would you ever use 80 PSIG to accomplish the goal? By reducing your compressed air from 80 down to 40 PSIG, you can easily reduce the air consumption of the “engineered” solution by another 40% + …………that’s the cherry on top of the cake when you compare the benefits of simply “bolting on” the solution of an engineered air nozzle vs. an open pipe in the first place. Then there is the issue of taking advantage of the pressure differential (from 80 down to 40 PSIG) that creates a little bit more air volume capacity. At 80 PSIG, your compressed air to free air volume ratio is 6.4:1. At 40 PSIG, it is only 3.7:1. The net effect is you effectively have an overall larger volume of air at the disposal of the application which is always a good thing.

Regulating pressure is definitely warranted given the benefits that compliment the operation of the core EXAIR products.

If you need a deeper understanding about how EXAIR’s products can help your application, feel free to contact us and we will do our best to give you a clear understanding of all the benefits that can be had by our products’ use as well as proper implementation of accessory items such as compressed air filters and regulators.

Neal Raker, International Sales Manager
nealraker@exair.com
@EXAIR_NR
www.EXAIR.com 

Spending Some Extra Time Can Save Money (and Stress)

If you are familiar with our blog, you will see where I have recently written about coaching my oldest son’s pee wee football team this year. Things slowed down this past week as the team had a bye so that meant a “free” weekend or as my wife called it – “a chance to do some of the things you have put off over the last few months”. On the top of the list was painting our bedroom.

painting

Not my idea of a fun weekend!

My oldest son loves to help with projects and I never want to discourage him so when he asked if he could help, of course the answer was “yes”. Not only did this mean I had to spend some extra $ to get some supplies “for kids”, as he put it, I also needed to spend some time explaining what he needed to do. As we started to prep the walls, I went ahead and cut in around the ceiling, doors, baseboard and trim. My plan was that I would paint the top portion of the wall while he worked on the lower. I set up his little roller and watched him paint about a 4 foot wide section and much to my surprise he did a pretty good job. My wife needed a hand with our infant son, so I felt somewhat confident leaving our oldest unsupervised for a few minutes. BIG mistake!

When I got back upstairs, he had painted over the baseboard, trim and managed to drip paint all over the hardwood floors. When I asked him what happened, he responded with “well dad, I wanted to hurry because it’s really nice outside and I NEED to go out and play! Besides you said you were going to have to clean up anyway”. Go outside son, PLEASE, go outside and play. Now not only did I have to clean up the paint, but I also had to spend more money on new baseboard and trim because there is no way I was going to be able to salvage his masterpiece. Maybe I should have spent a little while longer explaining the process? Regardless, my next few moments of “free” time have all been filled.

Taking the time to review your compressed air system can be very important to your company’s efficiency. In many industrial settings/facilities, the compressed air system is an opportunity for savings and efficiency. In fact, the largest motor in a plant is often on the compressor itself. Leaving a small compressed air leak unattended or using an inefficient blowoff for a long period of time can result in very expensive electrical waste. This excessive expense and waste can negatively affect a company’s profit margin as well as reduce performance and increase production costs.

Luckily, EXAIR can help optimize your compressed air system by using our 6 Simple Steps:

6 steps

Measure the compressed air usage using a flow meter. Once you have identified your usage, you can work on finding a more efficient alternative.

Use a leak detector to locate expensive, wasteful leaks.

Replace the inefficient sources with a more efficient engineered solution

Operate the compressed air only when it’s needed. Our Electronic Flow Control (EFC) is an ideal choice to use for on/off service or to set up on a timed basis.

Install a Receiver Tank to provide additional compressed air supply for applications requiring large amounts of compressed air.

Control the supply pressure to the device using a regulator. Sometimes operating at lower pressure can still be effective and can reduce the overall energy cost of the operation. 

While I can’t recommend my son to lend (2) little helping hands, I might be able to provide some assistance with optimizing your compressed air system. Give us a call at 800-903-9247 to see how we can help.

Justin Nicholl
Application Engineer
justinnicholl@exair.com
@EXAIR_JN

 

Painting Supplies image courtesy of TedsBlog via Creative Commons License

 

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