The compressed air for your facility could account for anywhere from 10%-30% of your facility’s electrical costs. Meanwhile, 76% of your compressor’s lifetime cost comes from the electricity it uses. With such a considerable portion of your energy bill on the line, you must root out inefficiencies. Air compressor leaks waste energy, maybe more than you realize. Even leaks that are too small to hear or feel can reduce the pressure in your tank and add to your energy costs. Air leaks can also cost you in other ways, making them one of the biggest concerns you didn’t know you had.
How to Calculate the Real Cost of Compressor Air Leaks
A leaky air compressor is less efficient. It’ll use more energy and be less reliable than a compressor in perfect condition. Whether or not you realize your compressor leaks, you’ll pay for it on your energy bills. Exactly how much are your air leaks costing you? First, it depends on how much leakage you have. To estimate, follow these steps:
- Time how long it takes for your compressor to drop from its operating pressure (P1) to half of its operating pressure (P2), in pounds of force per square inch (PSIG). Write down the total time (T) in minutes.
- Subtract P2 from P1, and multiply that number by the total system’s volume (V), including all downstream receivers, piping and air mains, in cubic feet. Your manufacturer usually lists volume in gallons. To convert to cubic feet, divide the total gallons by 7.48.
- Take V multiplied by the result of P1 minus P2 and divide it by T times 14.7. Finally, multiply your answer by 1.25.
The formula for calculating leakage is [V * (P1 – P2) / (T * 14.7)] * 1.25. To keep things simple, let’s imagine a 5-cubic-foot compressed air system. Starting at 100 PSIG, it takes the system 60 minutes to reach the end pressure of 50 PSIG. Plug these numbers into the formula, and you get [5 * (100-50) / (60 * 14.7)] * 1.25. Do the math, and you’ll arrive at 0.354, or 35.4% leakage.
A normal system will experience 10% leakage, and anything above that is a sign you have leaks to patch. To understand how much your leaks are costing you, you’ll need to know how many leaks you have and the leakage rate. The Department of Energy (DOE) offers a useful chart to help you find the leakage rate for different diameters and shaped holes at your operating pressure.
Once you know these two numbers, you’ll also need to know how many kilowatts (kW) it takes to produce 1 cubic foot per minute (CFM), the number of hours your system operates each year and your energy cost per kilowatt-hour (kWh). The kW per CFM can vary slightly by machine and should be around 19 kW per 100 CFM, or 0.19 kW per CFM. You should know your energy cost from your energy bill. Otherwise, you can substitute the current national average for the industrial sector, which is around $0.07 per kWh ($/kWh). Multiplying all these figures together will give you your annual cost due to leakage.
The leak cost formula is the number of leaks * leakage rate (CFM) * (kW/CFM) * operating hours per year * ($/kWh). For example, let’s say you discover five 1/4-inch circular holes on a system that runs on 90 PSIG. According to the DOE leakage rate chart, your leakage rate is 89.2 CFM. Let’s also say your compressors run 7,000 hours a year, your energy costs $0.07 per kWh and your compressors use 0.19 kW/CFM. Following the formula, you would calculate 5 * 89.2 * 0.19 * 7,000 * $0.07. In this situation, the energy cost per year adds to $41,522.60.
Other Losses From Air Compressor Leaks
If your air leak cost estimate isn’t enough, consider these other ways your leaks cost you:
1. Financial Losses
An air compressor costs more to operate than the initial purchase. Industrial air compressors require vast amounts of energy. When they don’t run as efficiently as they should, a portion of that energy use doesn’t contribute to running your facility. If you need 100 CFM of air, and your leakage level rests at 30%, you have to produce 130 CFM of air to compensate.
For reference, an air compressor consumes between 18 kW-22 kW per 100 CFM. Therefore, producing 30 CFM more to compensate for air loss increases the energy cost by about 30%. The Compressed Air and Gas Institute (CAGI) estimates a 1/4-inch leak could cost you anywhere from $2,500 to upwards of $8,000 a year. The Environmental Protection Agency (EPA) estimates the cost is around $30-$90 per shift.
2. Productivity Losses
Your pneumatic tools and equipment need a precise amount of air to work at peak efficiency. When you have an air leak, they may not get the air amount they’re supposed to. Underpowered equipment may take longer to get tasks done and may not produce the same results.
Another source of productivity loss is with the machine itself. When your compressor leaks, it works harder to produce enough compressed air. The added stress causes more wear to the system, which increases its lifetime cost and makes it less efficient over time.
3. More Downtime
Along with productivity losses, there is the increase in downtime. Air leaks can shorten your maintenance intervals and cause unexpected failures. When your whole system relies on compressed air, frequent maintenance and repairs can bring operations to a grinding halt. An inefficient, leaky air compressor will also have to cycle more frequently. The more the system must cycle, the more often you may experience downtime.
4. Unnecessary Capacity Additions
A leaky air compressor might expel anywhere from 20%-30% of the compressed air it generates. That means you have up to 30% less usable compressed air than your machine should produce. If you invested in a compressor with just the right amount of capacity you need, your tools won’t get enough pressure to do their jobs. If you don’t realize you have a leak, you may source more equipment to keep pace. On top of the unnecessary purchase, it’ll take up more floor space and add another asset to maintain.
Finding Compressor Air Leaks
Undetected leaks hurt your bottom line and your competitiveness. An air compressor leak detection program can help. When you schedule leak checks every three months, you can spot problems before they grow and eat into your production costs more.
Two basic compressed air leak detection methods can help you pinpoint your leaks. One way is to listen for them. During non-production periods, walk around the facility and listen for leaks. You may spot them by their characteristic hiss or wheeze. You might also feel the air escaping, even if the sound is too quiet to hear.
Since not all leaks are large enough to be heard, felt or seen, the industry prefers the ultrasonic leak detector method. An operator can use a leak detector coupled with a pair of headphones or an indicator to find the leaks’ precise locations, even during noisy production times. Ultrasonic leak detectors are accurate and simple to use.
As you walk through, with or without a detector, check the most common areas where leaks spring, including:
- Tubes: The metal tubes tend to leak air at their connection points. Check any areas that look rusty or cracked.
- Air hoses: The air hoses throughout your system can also leak. If you don’t have an ultrasonic detector, you can find the tinier leaks with some hand soap. While the system is unplugged, cover the hoses in soap and a small amount of water. When you power on the system, any area where bubbles form has an air leak.
- Connectors: The connectors at the ends of hoses will make a wheezing sound if any air escapes. They’re particularly vulnerable to leaks.
After finding all the leaks, determine which ones to fix. You won’t need to patch them all to reap significant cost savings. Mending 10 1/4-inch leaks will save you more money than 50 1/16-inch leaks. Repairing those 50 leaks will also net you more savings than 100 1/32-inch leaks.
Common Causes of Compressor Air Leaks
Knowing what causes air leaks can help you prevent more of them in the future. Some of the reasons your air compressor system leaks air might include:
- Disconnects: Hoses, tubes and push-to-lock connection points are a common concern. If the connection point is worn out or isn’t correctly attached, it lets air escape. If any seals are missing O-rings, they aren’t properly sealed.
- Missed welds: Pipes, metal tubing and flanges can cause leaks at their joints, especially with a gap in the welding.
- Worn materials: Packing at the cylinder rods, control valves and shut-off valves may become worn out over time. Have them repacked whenever they show signs of wear.
- Incorrect sealants: The wrong type of thread sealant or an improper application won’t guard against leaks. Use the right materials and follow their instructions.
- Incorrect filter installation: Filters, regulators and lubricators with a low initial cost can seem like great deals. However, these cheaply made components are more likely to leak.
- Dirty seals: Seals with grime, dust and dirt won’t be air-tight.
- Increased pressure: The higher the pressure, the more air leakage you’ll experience through existing orifices.
- Old tools and equipment: You may lose air on the side of your pneumatic equipment. Disconnect and replace broken or leaky machines.
Fixing Compressor Air Leaks
The root cause of most air leaks usually lies in poor maintenance. If you’re not regularly tightening connections and replacing worn parts, leaks will spring up over time. First, tighten up all the connectors. Reduce the number of connection points if possible. Replace anything that won’t fit properly even after tightening.
Next, replace or repair any worn components, such as:
- Hose and tube sections: Isolate leaks to particular sections of hoses and tubes, and replace the leaking portion. If you can also shorten the distance between the compressor and the tools, do so.
- Valve seals and O-rings: Since valves are particularly vulnerable to leaks, replace the seals and O-rings regularly. Note these rubber components break down over time because of their exposure to heat and pressure.
- Condensate drain: Condensate traps collect and separate water most efficiently when they are clean. As they wear out, they can cause air leaks because they are adjacent to the compressor tank. Replace these water trays and drains regularly.
While most leaks come from loose fittings and worn parts, a leak in the compressor tank itself is a different story. On the tank, leaks can spring rust or gaps in the welding at seams and joints. Here’s how to fix an air compressor tank leak:
- Disconnect the hoses: First, detach all hoses and tools from the compressor and charge it completely. Use a spray bottle with soapy water or an ultrasonic detector to find the individual leaks. If you’re finding leaks that aren’t along seams and welding, it’s time to replace the tank entirely.
- Tighten the fasteners: For safety, pull the emergency release valve and let the air escape and relieve the pressure. Around the tank, tighten any loose screws and fasteners. Remove and replace them if they’re rusty or worn out.
- Check for persistent leaks: Next, recharge the compressor. Using either the soap bubble method or an ultrasonic detector, check for leaks. Mark all the leaks around seams and welded brackets.
- Grind down leaks: Power down the machine and release the air pressure again. Use an angle grinder around the leaks you’ve marked. Flatten out the raised metal at welds and seams until you’ve exposed the crack or hole and the areas are flush against the rest of the tank.
- Seal the area: First, light a brazing torch and increase the oxygen until you have a bright blue flame. Heat the surface surrounding the hole. Next, press a brass brazing rod to the heated area and continue heating it with the flame until the material melts and pools along the surface. Continue until the ground down area is resealed. Wait for the weld to dry and cool before recharging the compressor.
For the best outcome on leak repairs in the connectors, components and the tank itself, hire a professional. The Titus Company offers compressor system service and repair to correct your leaks safely and efficiently. Our highly trained technicians help you get maximum energy savings by prioritizing the most cost-draining leaks and using industry- and manufacturer-approved maintenance techniques.
The Importance of Preventing Compressor Air Leaks
As with most repairs, it saves time and costs less to prevent issues than to resolve them. Even when you’re prompt to repair leaks, servicing your system creates downtime. Preventive maintenance can be scheduled for convenient times and creates less downtime than remedying problems after they occur.
By preventing leaks, your facility runs more efficiently all the time. Your tools get the pressure they need to function efficiently. Since you’ll have fewer leaks, you won’t have to play a constant game of catch-up. You’re also less likely to be caught off-guard by a major leak that shuts down a compressor and the equipment relying on it. With fewer leaks, you’ll save money on repair costs.
Prevent leaks through a combination of scheduled professional maintenance and employee training. Plan to check your facility for leaks about once a quarter. This is an excellent time to schedule regular maintenance and revisit previously patched leaks. When discovering new leaks, tag and repair them. Then, verify your system is running at improved efficiency as a result of the repairs.
On the training side, implement a reporting program so employees can notify you of leaks they discover. Teach them how to spot leaks and worn out parts that may cause them. Your staff will be the first to notice when machines aren’t getting the correct air pressure. Incentivizing them to report potential leaks can help you get ahead of leak concerns. Your team should know how to secure air hose connections and take other steps to help prevent leaks.
Review Your Compressed Air System for Free
The Titus Company offers a free air compressor system review to help you understand your leak situation and how to fix it. Our comprehensive review covers compressed air leak detection, solutions and preventive maintenance recommendations. We can also uncover some of the other inefficiencies costing your company money, such as moisture buildup or inefficient system designs. Though located in Pennsylvania, we also offer emergency service and preventative maintenance in Northern Virginia, Delaware, Maryland and the New Jersey area.
Contact us to request more information about our free system review or our leak repair and prevention solutions.