Critical Factors to Consider When Designing Your Compressor Room

One common thing that can be easily overlooked is the importance of designing an efficient compressor room. After you’ve determined your overall requirements and selected the appropriate compressor, you can begin designing the layout of your compressor room. For starters, the compressor room should be located in a central location when possible, close to the point of use. This will help to minimize pressure drop as well as reduce installation costs as less piping will be required. If this isn’t possible, try to keep the compressor room close to the larger volume applications in your facility. Otherwise you will have to use larger diameter piping in order to ensure an adequate volume of air is available.

The diameter of the distribution piping should NOT be based on the connection size of the compressors, aftercoolers, or filters. According to the Compressed Air Challenge Best Practices for Compressed Air Systems handbook, piping should be sized so that the maximum velocity in the pipe is 30 ft/sec. When the distance between the compressor room and the point of use is lengthy, consider increasing the pipe diameter to minimize the pressure drop across the system.

Inside of your compressor room you’ll have a variety of different equipment, all dependent on the demand, quality, supply, storage, and distribution of your compressed air. Keeping all of the equipment in its own room will also provide some insulation from the noise associated with compressed air generation. It is crucial that the space selected as your compressor room is sufficiently large enough to accommodate everything without becoming cramped. As a general rule of thumb, keep about 3′ of space between equipment such as the compressor, receiver tanks, aftercooler, and dryer. This helps to prevent equipment from overheating as well as offers maintenance personnel adequate space with which to perform any regularly scheduled maintenance or repairs.

Once you’ve selected your equipment, piping, and determined the location, another thing to consider is ventilation. As compressed air is generated, the compressor gives off a good amount of heat. It is important that the exhaust air is not permitted to re-circulate throughout the compressor room. The exhaust needs to be ducted so that it the warm air is not drawn in at the air intake on the compressor. Some equipment, such as refrigerated dryers, require a substantial amount of cooling air. In these situations, an exhaust fan can be used to provide that additional airflow.

To further enhance the efficiency of your facility, the heat generated from compression can be re-purposed instead of simply exhausting into the ambient environment. This process is commonly referred to as compressed air energy recovery. Some industries require a source of heat for many of their manufacturing processes. In these scenarios, the heat energy that is produced during compression can be reused rather than having to generate another source of heated air. If the heated air can’t be used for any of your manufacturing processes, the heat can be used as a means to heat your water supply or even to heat the facility itself. This can drastically reduce your electricity or gas requirements during cooler periods.

To reduce the amount of required maintenance and ensure that your compressor is operating as efficiently as possible, the compressed air intake must also be free from particulate and harmful gases. When dust and dirt is drawn into the compressor, it can cause wear on the internal components. If the ambient environment contains a lot of dust and particulate, a pre-filter can be used to prevent any future problems. In these instances, it is important to consider the pressure drop that will be caused when designing the system.

Keeping these tips in mind will serve to make your life much easier in the long run. Once you have everything installed and set up, visit the EXAIR website or give us a call to speak with an Application Engineer. EXAIR’s Intelligent Compressed Air Products  can help you reduce compressed air consumption and increase worker safety by adhering to both OSHA 1910.242(b) and 1910.95.

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

Image Courtesy of  thomasjackson1345 Creative Commons Attribution-NoDerivs 2.0 Generic (CC BY-ND 2.0)

Intelligent Compressed Air: Refrigerant Dryers

When we talk with customers about their EXAIR Products, we also discuss the quality of their compressed air. Many of our products have no moving parts and are considered maintenance-free when supplied with clean, moisture free compressed air. One of the most critical aspects of a compressed air distribution system is the dryer.

No matter where you are in the world, the atmospheric air will contain water vapor. Even in the driest place in the world, McMurdo Dry Valley in Antarctica, there is some moisture in the air. As this air cools to the saturation point, also known as dew point, the vapor will condense into liquid water. The amount of this moisture will vary depending on both the ambient temperature and the relative humidity. According to the Compressed Air Challenge, a general rule of thumb is that the amount of moisture air can hold at a saturated condition will double for every increase of 20°F. In regions or periods of warmer temperatures, this poses an even greater problem. Some problems that can be associated with moisture-laden compressed air include:

  • Increased wear of moving parts due to removal of lubrication
  • Formation of rust in piping and equipment
  • Can affect the color, adherence, and finish of paint that is applied using compressed air
  • Jeopardizes processes that are dependent upon pneumatic controls. A malfunction due to rust, scale, or clogged orifices can damage product or cause costly shutdowns
  • In colder temperatures, the moisture can freeze in the control lines

In order to remove moisture from the air after compression, a dryer must be installed at the outlet of the compressor. It is recommended to dry the compressed air to a dew point at least 18°F below the lowest ambient temperature to which the distribution system or end use is exposed. A dew point of 35-38°F is often sufficient and can be achieved by a refrigerated dryer (Best Practices for Compressed Air Systems). This makes the refrigerant dryer the most commonly used type in the industry.

A refrigerant dryer works by cooling the warm air that comes out of the compressor to 35-40°F. As the temperature decreases, moisture condenses and is removed from the compressed air supply. It’s then reheated to around ambient air temperatures (this helps to prevent condensation on the outside of distribution piping) and sent out to the distribution system.

With your air clean and dry at the point of use, you’re making sure you get the most out of EXAIR’s Intelligent Compressed Air Products without adhering to pesky maintenance procedures.

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

Compressor image courtesy of Tampere Hacklab via Flickr Creative Commons License

Intelligent Compressed Air: What You Need To Know About Rotary Scroll Compressors

Humans have been using compressed air for just about as long as we’ve been using fire. The discovery of fire’s usefulness likely only slightly predates the discovery that blowing air on those flames increases their size, temperature, and intensity. Technically, our respiratory systems are single-stage, diaphragm operated air compressors!

Over the ages, engineer-type humans came up with mechanical methods to perform this task, which was primarily used to stoke fires. This was critical to the development of metalworking, which was key to the Industrial Revolution, which brought on more needs for compressed air, which led to better-equipped engineer-type humans developing the modern methods by which we compress air.

One of the most recent inventions to do this is the rotary scroll compressor. Similar to other rotary type compressors, they use a rotating shaft to decrease the space occupied by a specific amount of gas. By decreasing the space occupied without letting any of that gas out, the pressure increases. The “tricky” part about rotary scroll compressors is the incredibly tight tolerances needed to make it function effectively. In fact, the first patent for one (issued in 1905) predates the machining technology needed to make one by about forty years. And it was the 1970’s before they started to be manufactured for commercial use. Here’s how they work:

Two spirals, or scrolls, are intermeshed. The rotating (black) one orbits eccentrically with the fixed one, continually decreasing the volume for the gas to flow through (from the outer left & right sides) as it is pushed to the center, where it is fully compressed according to the compressor’s rating.

Key advantages/benefits of this design are:

  • Oil free air – no metal to metal contact of the scrolls means no lubrication is needed in the airend.
  • Pulsation free delivery – since the flow from suction to discharge is one continuous motion, the outlet pressure is constant and even.
  • Quiet operation – the lack of metal to metal contact, and continuous motion eliminate the mechanical noise inherent in, for example, the reciprocating pistons and slamming check valves in a piston type compressor.
  • Low maintenance – as in most cases, less moving parts = less to maintain.
  • Wide range of duty cycle – their design makes them particularly conducive to single & two-stage units, and efficient operation with modulating variable speed drives, meaning they handle low loads just as effectively as high loads.

Some disadvantages/drawbacks are:

  • Higher price tag – the precision machine tools, and their skilled operators, are not cheap, and neither are rotary scroll compressors.
  • Size restrictions – larger rotating scrolls generate higher centrifugal force. Because the tolerances are so tight, those higher forces necessarily limit the mass of the rotary element, which limits the size, and hence, the air flow they can push out. As a result, they’re limited to the neighborhood of 100 SCFM capacity.

This combination of pros & cons makes rotary scroll compressors especially popular in the medical and laboratory settings. A supply of clean air at a constant pressure, with the ability to handle constantly changing loads matter a LOT in those settings. 100 SCFM is a LOT of air flow in most of their applications, and relatively speaking, the air compressor generally isn’t even close to the highest priced piece of equipment in such facilities.

At EXAIR Corporation, we’re committed to help you get the most out of your compressed air system. To do that, it’s important to have a better understanding of these systems, from generation to end use. If you’d like to find out more, give me a call.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Rotary Scroll GIF:  used from  Public Domain
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How to Calculate ROI (Return on Investment)

You may have asked…why should I switch over to an engineered compressed air product if my system already works? Or…How can your products be much different?

Manufacturing has always been an advocate for cost savings, where they even have job positions solely focused on cost savings. Return on Investment (ROI) is a metric they look toward to help make good decisions for cost savings.  The term is used to determine the financial benefits associated with the use of more efficient products or processes compared to what you are currently using. This is like looking at your homes heating costs and then changing out to energy efficient windows and better insulation. The upfront cost might be high but the amount of money you will save over time is worth it.

ROI Calculation

How is ROI calculated? It is very simple to calculate out the potential savings of using an EXAIR Intelligent Compressed Air® Product. We have easy to use calculators on our websites Resources where filling in a few blanks will result in an ROI when switching to a EXAIR product! Here they Are, Calculators.

I’ll go ahead and break down the simple ROI calculations for replacing open blow offs with an EXAIR Super Air Nozzle:

  • ¼” Copper Pipe consumes 33 SCFM at 80 psig (denoted below as CP)
  • A Model 1100 ¼” Super Air Nozzle can be used to replace and only uses 14 SCFM at 80 psig (denoted below as EP)

Calculation:

(CP air consumption) * (60 min/hr) * (8 hr/day) * (5 days/week) * (52 weeks/year) = SCF used per year for Copper Pipe  

(33) * (60) * (8) * (5) * (52) = 4,118,400 SCF

(EP air consumption) * (60 min/hr) * (8 hr/day) * (5 days/week) * (52 weeks/year) = SCF used per year for EXAIR Product  

               (14) * (60) * (8) * (5) * (52) = 1,747,200 SCF

Air Savings:

SCF used per year for Copper Pipe – SCF used per year for EXAIR Product = SCF Savings

               4,118,400 SCF – 1,747,200 SCF = 2,371,200 SCF in savings

If you know the facilities cost to generate 1,000 SCF of compressed air you can calculate out how much this will save. If not, you can use $0.25 to generate 1,000 SCF which is the value used by the U.S. Department of Energy to estimate costs.

Yearly Savings:

                (SCF Saved) * (Cost / 1000 SCF) = Yearly Savings

                                (2,371,200 SCF) * ($0.25 / 1000 SCF) = $592.80 annual Savings

With the simple investment of $42 (as of date published) you can calculate out the time it will take to pay off the unit.

Time Until payoff:

                (Yearly Savings) / (5 days/week * 52 weeks/year) = Daily Savings

                                ($592.80/year) / (5 days/week * 52 weeks/year) = $2.28 per day

                (Cost of EXAIR Unit) / (Daily Savings) = Days until product has been paid off

                                ($42) / ($2.28/day) = 17.9 days  

As you can see it doesn’t have to take long for the nozzle to pay for itself, and then continue to contribute toward your bottom line. 

If you have any questions about compressed air systems or want more information on any of EXAIR’s products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.

Jordan Shouse
Application Engineer

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