Most industries rely on compressed air as a means of powering their most essential tools. Air compressors provide the punch necessary to drive impactors, drills and other equipment on assembly lines, which is why making sure they’re functioning at optimal performance is one of the best ways to reduce your company’s air compressor maintenance costs.
Compressed air’s power makes it the perfect energy source for intensive applications despite its inherent inefficiency. Most air compressors require four to eight times as much horsepower in electricity to create one horsepower worth of compressed air. Additionally, many factors make air compressors grow less efficient with time and without proper maintenance, including:
- Impure air: Air that contains dirt, dust or other impurities can cause gunk to accumulate inside an air compressor. This build-up wears on parts and reduces internal volume, which can lead to increased costs for repeated air compressor maintenance sessions.
- Humidity: Water has a high specific heat, which means it requires more energy to change its temperature. Additionally, it collects inside the air compressor as condensation and begins to rust out its parts from the inside. Ensuring that incoming air is as cool and dry as possible is one of the best ways to protect your investment and improve your air compressor’s efficiency.
- Hot air: Hot air has a lower density than cold air. In turn, cold air is naturally more “compressed” than hot air — which means it is far more efficient to pump cold air into your air compressor. And that helps in maximizing your air compressor’s efficiency, which leads to gains in productivity.
The goal of this article is not only to explore what affects air compressor efficiency but also to provide tips on how to maximize the efficiency of an air compressor. With that information, you can boost your air compressor’s performance, plus increase the lifespan of your air compressor, which will lower your energy costs and create higher rates of return.
Different Types of Air Compressors
Different types of air compressors are used in the industry and understanding the differences between them is an excellent start to maximizing air compressor efficiency.
Here are the most common types of air compressors in use today:
- Reciprocating compressor: These compressors use one or more pistons to compress air. The up-and-down motion of the pistons compresses air within the chamber and then releases it into the holding tank. A system of valves allows air in and out of these piston chambers.
- Rotary screw compressor: This type of compressor makes use of a set of helical screws to compress air. The compressor drives air into the chamber, and the helical screws push the air into a smaller and smaller volume thereby increasing the pressure of the trapped air. This is also true for other types of rotary compressors such as rotary vane units.
- Centrifugal air compressor: A set of radial blades compress air in this type of device. These blades suck air in through the center, and the high speed rotation of the blades compresses it.
- Oil-free scroll compressor: Due to the number of moving parts and metal-on-metal applications within air compressors, they usually require the use of oil to provide ample lubrication. Oil-free scroll compressors do not require continued lubrication and are the preferred tools for many clean facilities. There are other types of oil-free compressors as well, but this is a common one.
When it comes to air compressors, there are many different brands, each with unique designs and operation specs. Some reputable companies include Atlas-Copco, Boge, Mattei, Sauer and Sullivan Palatek. Buying the right type of compressor from a reputable company ensures a longer lifespan and higher returns on your investment.
What Factors Contribute to Air Compressor Inefficiency?
Maximizing air compressor efficiency starts with knowing what factors degrade it. An air compressor is a codependent system of controls and design, and these systems relate to each other in providing an efficient system.
Let’s look at the five most common suspects of lowered air compressor efficiency, as well as how to rectify them.
1. Use Your Air Compressor Controls Effectively
The controls of an air compressor are the link between the compressor’s output and the demanded load. Matching the controls to the capacity of the equipment is essential. Compressors are made to deliver a particular volume of air in a specified range of pressure, and the controls are what regulates their ability to stop when reaching that designated range. Conversely, they specify a minimum pressure at which the compressor should kick back on. Because sustained high pressure puts more strain on a system, it is advantageous to have a fine-tuned control system that can deliver consistent, usable pressure closer to the minimum requirement, rather than the maximum.
Here are some controls that can assist in increasing air compressor efficiency:
- Start and stop controls: These cue the compressor’s system to turn off and on, depending on the desired pressure.
- Load/unload controls: These work in conjunction with start and stop controls, telling the compressor to release pressure.
- Modulating controls: A compressor must monitor its own needs, such as flow, and modulating controls allow the user to tune this parameter. In comparison, multi-step controls offer the ability to operate without full pressure load.
- Dual and auto dual controls: These give the user the ability to select between the start and stop or load and unload switches.
- Variable displacement: This parameter allows the compressor to operate in multiple conditions of partial load.
- Variable speed drive: This control creates a continuum of power output in the motor, which eliminates quantized output and allows the engine to meet many different levels of demand.
- System master controls: An all-around set of controls for air compressors, these give the user a more streamlined ability to increase the device’s efficiency. System master controls are useful for more complex systems where the localized controls are not sufficient to handle the system. A good set of system master controls can even provide analytics and trends to help tune the system.
- Pressure and Flow Controllers: These work as a backup storage of energy, allowing a quick supply to be accessed if there is a dip in pressure.
By taking advantage of these controls, you can boost your air compressor’s efficiency.
2. Enhance Your Overall System Design
The design of an air compressor is one of the most significant factors in making it run efficiently.
Here are some tips for streamlining the design of your system and maximizing your air compressor’s efficiency:
- Size the distribution system properly. The size and material used for the compressed air distribution system can be critical to ensuring proper flow and pressure delivery to the most remote point-of-use locations. Using a smooth, non-corroding material like Teseo’s Aluminum Piping also helps assure proper flow and pressure delivery. If future expansion is anticipated, over-sizing the distribution system upfront will save thousands of dollars later on.
- Reduce bends and angles in the flow path. The presence of sharp turns increases the amount of friction in the compressed air, causing it to heat up and wear on parts. This heat production saps energy from the system and leads to higher pressure drops, which ultimately result in a lower pressure upon delivery. By straightening the flow path, the system will waste less energy and last longer.
- Prevent heat waste with a recovery system. Air compressors operate at about 10 percent efficiency — you lose most of the energy to heat. By using a heat recovery system, you can recover nearly all of the lost power and use it for warming your workspace or other applications.
- Use a storage tank to smooth pressure delivery. Storage tanks ease the overall curve of air pressure delivery by allowing an air supply to supplement the system when needed. If you purchase a storage tank, make sure to choose an appropriate size for your air compressor, horsepower and applications.
- Ensure incoming air is cool. There are several different ways to cool incoming air, such as with a heat exchanger, and doing so will immediately and dramatically reduce your energy consumption.
- Consider multiple small air compressors versus one large compressor. The higher the workload on a single compressor, the lower the efficiency. Consider installing several smaller air compressors instead of a larger one and using system master controls to have them work in sync. This way, when the load decreases, only some of the compressors will be in operation.
- Reduce or eliminate leaks. Loss of compressed air due to leaks in the distribution system not only results in lower pressure at point-of-use and the inefficiency that this can cause, but it also causes the compressor to run longer and harder to try to maintain system pressure. An effective leak management system can reduce the cost of operation of your compressed air system by as much as 25 to 30%.
With the above tactics, you’ll make your air compressor more efficient, plus reduce your air compressor costs by lowering the chance of unplanned maintenance work.
3. Examine Your System’s Needs
All too often, air compressors are mismatched and poorly tuned to the actual needs of the devices they power.
Here are some ways to ensure your system isn’t wasting energy:
- Lower the excess pressure in your system. Often, a system that only requires 60 psi to operate will draw 100 psi from an air compressor. This extra air ultimately sits unused, as the regulator keeps it from damaging the equipment, and gets discharged at the end of the usage period. Match the pressure in your system to the pressure required by your devices.
- Quantify all the requirements placed on your compressor. If your air compressor is powering multiple devices, add up the maximum pressure load they will require. This calculation allows you to see what size air compressor you need for your uses.
- Support your system with air storage tanks. Applications where different devices contribute to “peaking” periods — that is, periods where the compressor struggles to keep up with the demand — benefit from extra air storage. These tanks serve as reservoirs for air.
- Know your system’s load profile. A compressed air system may have to meet different levels of demand within a given period, and it needs to be able to operate efficiently at high and low loads. In many instances, using multiple compressors, or compressors equipped with variable speed of frequency drives, is preferable for handling more complex load profiles.
- Reduce your system pressure. Operating at the minimum pressure is one of the best ways to increase air compressor efficiency. Small boosts in pressure can lead to significant energy expenditures, so this should remain an ever-present goal.
- Break down your system with block diagrams. To maximize efficiency, you should measure the input pressure on every element in your air chain. This measurement includes the pressure drop across the device separating air and lubricant, plus the interstage and the different components. In doing so, you will be able to fine-tune the performance of your entire system.
By matching your air compressor to your applications, you’ll increase your air compressor efficiency and overall performance.
4. Reducing the Pressure Drop
A pressure drop occurs for different reasons, but minimizing the unwanted sources of it is one of the greatest gifts you can give your air compressor system.
Here are some tips on how to reduce pressure drops:
- Use proper pipe sizes: When pipes between distribution headers and equipment are improperly sized, inefficiency results. Make sure your piping can handle maximum flow rates — not only the average.
- Reduce moisture: Moisture leads to condensation, which leads to rust, which leads to leakage and increased flow resistance. Change air filters and maintain the drying equipment to keep moisture out of your system.
- Keep filters clean: When dirt obstructs air filters, it’s more difficult for the system to draw air inside and push it downstream. This situation leads to drops in pressure. It’s easily avoided, however, by maintaining a schedule for filter replacement.
- Aim for low-pressure drops: When purchasing items like dryers, separators, filters, regulators, lubricators, hoses, connections or aftercoolers, always go for the ones with the lowest possible pressure drop.
- Streamline the air flow path: The more distance air must travel, the higher the likelihood it will be lost. Design your system to move air the shortest possible distance.
With the above steps, you can expect an immediate, noticeable change in your air compressor’s efficiency.
5. Stick to a Regular Maintenance Schedule
Perhaps the most critical tool for maximizing air compressor efficiency in the long-term is to schedule regular air compressor maintenance dates. Due to the number of moving parts, the constant influx of air and the heavy usage that machines undergo, it is critical to keep yours tuned. Otherwise, factors like condensation and dirty filters will wear your system down, leading to an influx of repair expenses.
First and foremost, maintenance work should strive to detect leaks. Leaks are responsible for the vast majority of air loss and efficiency problems. Even a small one can waste enormous amounts of energy loss in an air compressor, putting additional strain on its motor and causing it to wear prematurely. The resulting drop in air pressure makes tools work harder and means more time to do the same job.
To approximate the amount of leakage in your system, divide the on-load time in minutes by the sum of the on-load and off-load times, and multiply the result by 100. If the product is more than 10, you should have your system checked for leaks. This assessment can be done fast and with accuracy using ultrasonic detectors. Repair the leakages in a timely and methodical fashion, prioritizing the most significant cracks and running regular checks for others.
As mentioned, keep a schedule for changing your filters and completing regular maintenance. Depending on your operation, this preventative step can be done either by employees trained in the procedures or by qualified technicians.
The Costs of an Inefficient Air Compressor System
Inefficient air compressor systems cost you in several ways:
- Money: Air compressors working to spec are fast, reliable and productive. When they work inefficiently, the same task that took 30 minutes may now take 40 minutes — that means more labor hours and increased electrical bills to operate the equipment.
- Time: Losing time also affects your bottom line by slowing output and decreasing profit potential. Keeping your air compressors efficient, operational and maintained ensures you will keep up with your production schedule.
Due to the potential losses, an air compressor system can have on your company and its bottom line, it’s critical to follow the earlier steps for how to make your air compressor more efficient. Some examples include completing routine maintenance, streamlining your system’s design or implementing company policies for the proper use of air compressor system controls. All can help you reduce air compression costs and maximize your air compressors’ efficiency.
Come to The Titus Company for Air Compressor Needs
If you work in the modern industry, then your business relies on well-designed air compressor systems that operate smoothly. The Titus Company specializes in high-end, efficient air compressors that supply enterprises with all the power they need to keep creating and driving that improved bottom line.
The Titus Company concentrates on several different products, including reciprocating, rotary screw, rotary vane, scroll and centrifugal lubricated and oil-free air compressors, as well as air and gas dryers and dehydration systems, including refrigerated, desiccant and membrane-type. We offer air and gas filters, oxygen and nitrogen generators, vacuum and blower packages, process chillers and coolers and dust collection systems too. Plus, we’re always ready to assist with 24/7 emergency service.