While I was still in college, I worked in a meat processing plant as a Project Engineer in the maintenance department. During my time in the maintenance department I learned the importance of proper maintenance on machines. A meat processing plant is one of the most taxing environments on machines as they will have to survive in extreme cold temperatures to extreme hot temperatures; they are also put through deep sanitation wash downs multiple times a day sometimes for periods of over an hour. The plant really put into perspective the importance of preventative maintenance of machines. This includes utilities such as a boiler and of course your air compressor.
A primary focus to prevent an increased amount of wear on your compressor motor is to seal up compressed air leaks. Leaks can cause the compressor to cycle more often and/or refill receiver tanks on a more frequent basis, causing the motor to run more often. With the motor having to run more often to keep the air present, it will wear down faster. Using EXAIR’s Ultra Sonic Leak detector, leaks can be found in the pipes so that they can be sealed up.
If you have any questions about compressed air systems or want more information on any EXAIR’s of our products, give us a call, we have a team of Application Engineers ready to answer your questions and recommend a solution for your applications.
Cody Biehle Application Engineer EXAIR Corporation Visit us on the Web Follow me on Twitter Like us on Facebook
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, dry 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 Antartica, 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. There are three primary types of dryers used in the compressor industry: refrigerant, desiccant, and membrane. Each style has it’s own inherent applications and benefits.
Refrigerant type dryers cool the air, removing the condensed moisture before allowing it to continue through the distribution system. These will generally lower the dew point of the air to 35-40°F which is sufficient for most applications. So long as the temperature in the facility never dips below the dew point, condensation will not occur. Typical advantages of a refrigerant dryer include: low initial capital cost, relatively low operating cost, and low maintenance costs. This makes them a common solution used in an industrial compressed air system.
Another type of dryer is the desiccant dryer. I’m sure you’ve seen the small “Do Not Eat” packages that are included in a variety of food products, shoes, medications, etc. These are filled with a small amount of desiccant (typically silica gel) that is there to absorb any moisture that could contaminate the product. In a desiccant dryer, the same principle applies. The compressed air is forced through a “tower” that is filled with desiccant. The moisture is removed from the air supply and then passed into the distribution system. One minor drawback with a desiccant type dryer is that the desiccant material does have to periodically be replaced. Desiccant dryers can also be used in addition to a refrigerant dryer for critical applications that require all water vapor to be removed.
The third type of dryer is the membrane dryer. In this style, extremely low dew points are able to be achieved. This makes them the optimal choice for outdoor applications where the air could be susceptible to frost in colder climates. They are also ideal for medical and dental applications where consistent reliability and air quality is an absolute must. A membrane dryer does not require a source of electricity to operate and its compact size allows it to be easily installed with minimal downtime and floor space. Maintenance is minimal and consists of periodic replacement of the membrane. While they are good for some applications, they do come with limitations. They do limit the capacity of the system with variations ranging from as little as 1 SCFM to 200 SCFM. Because of this, they’re often used as a point-of-use dryer for specific applications rather than an entire compressed air system. Some of the compressed air must be purged with along with the moisture which consumes excess compressed air.
Regardless of what products you’re using at the point-of-use, a dryer is undoubtedly a critical component of that system. Delivering clean, dry air to your EXAIR Products or other pneumatic devices will help to ensure a long life out of your equipment.
Take a second and think about where the air compressor is located within your facility. It is more than likely not a major focal point displayed prominently in the floor layout. There is a better chance it is tucked away in a corner of the facility where operators seldom travel. No matter the type of air compressor, it still has an intake where it pulls in the ambient air from around the compressor then sends it through some process and on the demand side of your compressed air system. These intakes can easily be placed out of sight and out of mind especially in older facilities that were designed when compressors were loud and the piping layout kept them away from operators due to sound level restrictions.
That’s why your compressor manufacturer supplies a specific grade of air 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. It’s just like changing the air filter on your car, your car needs clean air to run correctly, so does your compressor and the entire demand side of your compressed air system.
According to the Compressed Air Challenge, as a compressor inlet filter becomes dirty, the pressure drop across the inlet increases, this is very similar to the point of use compressed air filters. The inlet filter on the compressor is the only path the compressor has to pull in the air, when restricted the compressor can begin to starve for air very similar to if you only had a small straw to breath through and told to run a marathon. A clogged inlet filter can give false symptoms to compressor technicians as well.
The effects can mimic inlet valve modulation which result in increased compression ratios. If we were to form an example based on a compressor with a positive displacement, if the filter pressure drop increases by 20″ H2O, a 5% reduction of the mass flow of air will be present without a reduction in the power being drawn by the compressor. This all leads to inefficiency which easily amounts to more than the cost to replace the depleted inlet air filter.
Where you place the filter is just as important as how often you replace it. There are some tips to be used when mounting the inlet filter.
The filter can be placed on the compressor, but the inlet pipe should be coming from an external area to the compressor room or even the building if possible. The inlet should be free from any contaminants as well. Some examples that are easy to overlook are nearby condensate discharges, other system exhausts and precipitation.
Depending on the type of compressor being used, a lower intake air temperature can increase the mass flow of air due to the air density. A compressor that is lubricant injected is not susceptible to this due to the air mixing with the warmer lubricant before being compressed.
If you would like to discuss improving your compressed air efficiency or any of EXAIR’s engineered solutions, I would enjoy hearing from you…give me a call.
The electrical costs associated with generating compressed air make it the most expensive utility in any industrial facility. In order to help offset these costs, it’s imperative that the system is operating as efficiently as possible. I’d like to take a moment to walk you through some of the ways that you can work towards making your compressed air system more efficient.
The first step you should take is to identify and fix any leaks within the distribution piping. According to the Compressed Air Challenge, up to 30% of all compressed air generated is lost through leaks. This ends up accounting for nearly 10% of your overall energy costs!! To put leaks in perspective, take a look at the graphic below from the Best Practices for Compressed Air Systems handbook.
Compressed air leaks don’t just waste energy, but they can also contribute to other operating losses. If enough air is lost through leaks, this can also cause a drop in system pressure. This can affect the functionality of other compressed air operated equipment and processes. This pressure drop can affect the efficiency of the equipment causing it to cycle on/off more frequently or to not work properly. This can lead to anything from rejected products to increased running time. With an increase in running time, there’s also the need for more frequent maintenance and unscheduled downtime.
You can perform a compressed air audit in your facility using an EXAIRModel 9061 Ultrasonic Leak Detector. If you’d prefer someone come in and do this for you, there are several companies that offer energy audit services where this will be a focal point of the process.
Speaking of maintenance, proper compressor maintenance is also critical to the overall efficiency of the system. Like all industrial equipment, a proper maintenance schedule is required in order to ensure things are operating at peak efficiency. Inadequate compressor maintenance can have a significant impact on energy consumption via lower compressor efficiency. A regular preventative maintenance schedule is required in order to keep things in good shape. The compressor, heat exchanger surfaces, lubricant, lubricant filter, air inlet filter, and dryer all need to be maintained. This can be done yourself or through a reputable compressor dealer. The costs associated with these services are outweighed in the improved reliability and performance of the compressor. A well-maintained system will not cause unexpected shutdowns and will also cost less to operate.
The manner in which you use your compressed air at the point of use should also be evaluated. Inefficient, homemade solutions are thought to be a cheap and quick solution. Unfortunately, the costs to supply these inefficient solutions with compressed air can quickly outweigh the costs of an engineered solution. An engineered compressed air nozzle such as EXAIR’s line of Super Air Nozzles are designed to utilize the coanda effect. Free, ambient air from the environment is entrained into the airflow along with the supplied compressed air. This maximizes the force and flow of the nozzle while keeping compressed air usage to a minimum.
Another method of making your compressed air system more efficient is actually quite simple: regulating the supply pressure. By installing pressure regulators at the point of use for each of your various point of use devices, you can reduce the consumption simply by reducing the pressure. This can’t be done for everything, but I’d be willing to bet that several tasks could be accomplished with the same level of efficiency at a reduced pressure. Most shop air runs at around 80-90 psig, but for general blowoff applications you can often get by operating at a lower pressure. Another simple, but often overlooked, method is to simply shut off the compressed air supply when not in use. If you haven’t yet performed an audit to identify compressed air leaks this is even more of a no-brainer. When operators go to lunch or during breaks, what’s stopping you from just simply turning a valve to shut off the supply of air? It seems simple and minute, but each step goes a long way towards reducing your overall air consumption and ultimately your energy costs.
Rarely does the compressed air demand match the supply of the compressor system. To keep the generation costs down and the system efficiency as high as possible Compressor Controls are utilized to maximize the system performance, taking into account system dynamics and storage. I will touch on several methods briefly, and leave the reader to delve deeper into any type of interest.
Start/Stop – Most basic control – to turn the compressor motor on and off, in response to a pressure signal (for reciprocating and rotary type compressors)
Load/Unload – Keeps the motor turning continuously, but unloads the compressor when a pressure level is achieved. When the pressure drops to a set level, the compressor reloads (for reciprocating, rotary screw, and centrifugal type)
Modulating – Restricts the air coming into the compressor, as a way to reduce the compressor output to a specified minimum, at which point the compressor is unloaded (for lubricant-injected rotary screw and centrifugal)
Dual/Auto Dual – Dual Control has the ability to select between Start/Stop and Load /Unload control modes. Automatic Dual Control adds the feature of an over-run timer, so that the motor is stopped after a certain period of time without a demand.
Variable Displacement (Slide Valve, Spiral Valve or Turn Valve) – Allows for gradual reduction of the compressor displacement while keeping the inlet pressure constant (for rotary screw)
Variable Displacement (Step Control Valves or Poppet Valves) – Similar effect as above, but instead of a gradual reduction, the change is step like (for lubricant injected rotary types)
Variable Speed – Use of a variable frequency AC drive or by switched reluctance DC drive to vary the speed of the motor turning the compressor. The speed at which the motor turns effects the output of the system.
In summary – the primary functions of the Compressor Controls are to match supply to demand, save energy, and protect the compressor (from overheating, over-pressure situations, and excessive amperage draw.) Other functions include safety (protecting the plant and personnel), and provide diagnostic information, related to maintenance and operation warnings.
If you would like to talk about compressed air or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.