Air Compressor Efficiency & Performance

Improving air compressor efficiency has provided a competitive advantage in the world of growing energy costs and increasing accessibility to energy-saving technologies. According to the U.S. Department of Energy, compressed air systems consume around 10 to 30% of all energy of the average industrial facility. Experts at the U.S. Department of Energy say that the energy efficiency of a typical compressed air system can be improved 20% or more, which can save thousands of your energy dollars. We have prepared a list of the four most popular ways to enhance the performance of your air compressor.

Air leaks account for 25-30% of air wasted in compressed air systems

      1. Inspect for Air Leaks Annually Leaks decrease air compressor efficiency more than most realize. In fact, leaks waste as much as 20-30% of the energy generated by air compressor systems. Leaks can also impact the operation of the air equipment. They cause pressure changes that affect production efficiency, boost up operating costs by increasing the compressor’s capacity and run time. Also, leaks decrease service life and raise maintenance costs. Leaks most commonly happen around hose, pipe or port connections, so these areas of your equipment should get the most of your attention. Although not as common, leaks that happen at the source waste the most of your energy dollars since the pressure at the source is the highest.

        To detect leaks, you can use an ultrasonic leak detector. It identifies high-frequency hissing sounds typical for air leaks. Many facilities find out about leaks for the first time during the energy audit done by their compressed air specialist. The ultrasonic detector is a much faster (and less messy) way than the soapy water method, where a mixture of soap and water is applied to suspect areas with a paintbrush and observed for bubbling at the application site.

        The U.S. Department of Energy recommends using the following formula to calculate the annual savings costs after eliminating leaks: Cost savings = # of leaks × leakage rate (cfm) × kW/cfm × # of hours × cost kWh. Assuming that over the course of a year ten leaks happen at a size of 1⁄16 inch, the leak rate would be 6.31 cfm2 at the pressure of 100 psig (see Table 1). If the air compressor requires 18 kW to generate 100 cfm of compressed air at the average cost of $0.1 kW and the air compressor works around 7500 hours per year the average savings would be: 10×6.31×18/100×7500×0.1= $8,518.50

        Average energy savings when air compressor system leaks are addressed to improve efficiency
        Table 1. Leakage rates (cfm) for different supply pressures and approximately equivalent orifice sizes. Source: ENERGY STAR®


        There is also an online calculator developed by Kaeser where you can enter your system parameters and instantly see the potential savings. In addition to leak detection, we recommend incorporating an annual leak inspection as a long term strategy of increasing your air compressor’s efficiency at your facility. After the leak is detected, work with your compressed air specialist to evaluate the air supply and adjust the system pressure and other controls.

      2. Avoid Over-pressurization Optimizing air compressor load and reducing system pressure can generate around 15% energy savings. Use the lowest operating pressure suitable for your needs. The typical industry standard applies when you drop system pressure by 2 psi, operating costs reduce by around 1%. Remember that only a few industries require the system pressure over 100 psi and almost always there is a way to optimize this number. Continuously monitor your pressure gauges and use good quality pneumatic components. Install and inspect pressure regulators throughout the entire system to decrease loading and wear. To test the pressure regulator measure outlet pressure and inlet pressure. If they are the same, the pressure regulator is not working properly and does not regulate the system pressure. By dropping system pressure by 2 psi, you can reduce operating costs bv around 1%
      3. Eliminate Pressure Drops Pressure drops occur when the compressed air travels through the system from the compressor discharge to the actual point of use. To compensate the drop, operators often increase the generator pressure or turn up the regulators. As a result, the system starts consuming more energy. Around 10% of the discharge pressure drop is considered normal and happens even in a well-designed systems.

        There are two main reasons that cause a system to lose pressure. Complicated pipework is one of them. When the air passes the pipes, minimal friction occurs between a pipe’s surface and air molecules. If the pipe is too small for the amount of air that passes through, the velocity of the air increases and the amount of friction happening between the pipes and the air grows. This causes a loss in power generated by the system. Elbows, junctions and shut-off valves increase energy losses because of the change of the air flow.

        To address this challenge, air compressors should be built using the simplified pipework system whenever possible. Using an integrated valve/actuator unit is an effective way to prevent pressure drop between a valve and actuator. This system combines valve block, flow controls, cushioning and sensors into a single unit. Additionally, direct actuation of the unit provides results in faster shifting.

        An inefficient filtration process is the second reason that causes pressure drops. When replacing the filters, choose the correct size, level of filtration and change the filters regularly. To automate the filter change alert process and eliminate human errors, use “smart sensors” that monitor pressure drops for you and send you alarms in the pressure in the system changes. Remember that blocked filters reduce the pressure in the system which increases the energy consumption. Changing filters on a regular basis saves the energy and keeps you on track with the preventative maintenance best practices.
        Parker SensoNODE Bluetooth-enabled sensors for monitoring fluctuations in equipment
        Parker SensoNODE Bluetooth-enabled sensors for route-based monitoring that track the performance fluctuations of your equipment and send you alerts in real-time through Voice of the Machine (VoM) Industrial Mobile App.


      4. Replace compressed air with different energy sources and air delivery mechanism At times compressed air is not the most energy efficient power source for certain applications. For example, you can use a vacuum pump to create a vacuum. Dedicated air blowers could be an alternative to the air compressors for removing dirt/powder. If compressed air is needed, choose the right type of air compressor and utilize the control systems to maximize the savings. Parker air saver unit could be a great example of a control system used in the air compressor to remove dust and powder from the products moving on a conveyor line before assembly. The air saver unit is a valve that converts a continuous air blow into a pulsed air blow and does not require any external controls. Pulsing air technology of the air saver unit reduces air consumption by up to 50% which in addition to savings also improves efficiency. Air saver units can be used in many applications that require air blow such as bottle transfer, car painting process, swarf removal, cooling, ionizer dust removal, etc.

Preventive Maintenance Improves System Efficiency and Lifespan

    To sum up, air compressor efficiency always depends on the design and preventative maintenance measures taken to ensure that the system runs smoothly. Inspecting for leaks, changing filters regularly, using pressure regulators and operating the system on a minimal pressure required should become your priority. Working with your air compressor specialist to look for energy-saving opportunities will save you money and improve the efficiency of your system.

Additional Reading

Planning to Upgrade Your Compressor?

You may qualify for energy rebates with your power utility when you upgrade to an energy-efficient compressor. 

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