The operation of an air system requires more than just an ability to turn the right switches. One of the most important aspects of the whole operation is the maintenance of the compressor and various other components, because this ensures long life and efficiency for an air system. Unfortunately, compressed air maintenance mistakes are often made by operators who’ve only familiarized themselves with the basic workings of the equipment.
Common mistakes in compressed air maintenance include failure to assess energy costs and the impacts of contamination and condensation. These mistakes alone can lead to inefficiency and parts failure that can result in losses in the tens of thousands over the course of a given year. Further compressed air maintenance mistakes include a lack of attention to secondary components and a failure to properly train all members on staff of the finer nuances of compressor operation.
For obvious reasons, the stakes are high when it comes to the maintenance of compressed air systems. Read on to learn how to avoid the most common mistakes in compressed air maintenance.
Being Unaware of Compressed Air Energy Costs
One of the biggest compressed air maintenance mistakes is to underestimate or miscalculate the amount of energy that a compressor will use within the span of a year. Fact is, the price to operate an air compressor can equal or exceed the purchasing cost of the machine in the space of just 12 months. Most problematic in this regard is the wasteful usage of a compressed air system, which often occurs when operators are unaware of the overall energy costs.
On average, an industrial air compressor will retail in the ballpark of $30,000 to $50,000. When you multiply the operating costs per hour by the number of usage hours per day across 12 months, the cost of operating the machine during the first year alone could well exceed the initial price, and that doesn’t even count any possible maintenance costs.
A reliable way to estimate annual energy costs is to take the compressor’s horsepower and multiply that by .746, then multiply that by the number of usage hours, then multiply that by the power rate, and finally divide the total by the motor efficiency.
To best assure efficiency, it’s important to accurately calculate the annual energy costs of an air compressor, and to make sure that all operating staff understand how the figure plays out on a daily basis. That way, wasteful system use can be curbed going forward.
Limiting Inspections to the Air Compressor
Among certain air system operators, it’s simply assumed that maintenance begins and ends with a check of the compressor for signs of condensation and dirt. For operators who overlook the broader maintenance steps, the consequences can be confusing. After all, you can have a set of air compressors that function perfectly, yet still have problems with the overall system.
Even though the compressor is the main component of concern within an air system, it’s not the only one in need of routine maintenance. Of equal importance during any maintenance inspection are the other components that facilitate the air supply. Chief among such components is the air receiver, which holds compressed air for times when air demands increase, and also reduces system wear and contamination.
The air receiver makes it possible to run the compressor at lower levels and conserve energy in the process. However, the air receiver won’t be able to do its job properly if it’s too small for the system, because the compressor will have to run longer than necessary to keep up with air demand. Therefore, it’s important to ensure that the air receiver is either large enough for the system, or backed with secondary receivers.
Ignoring Air Leaks
Air leaks can waste up to half the air produced within a compressed air system. When it comes to the operation of an air compressor, some of the greatest savings can be made with regular air–leak maintenance.
To understand the cost of an air leak, imagine the waste of just one small leak within a system. For instance, in a 100 psi system, a leak of merely 1/4 inch will pass around 100 cfm. On a system that runs 24/7 at $0.07 kW, the leak could waste approximately $12,000 of compressed air per year. Surprising as it sounds, an air leak small enough to evade the naked eye can in fact result in losses that will extend into the tens of thousands.
Granted, the process of air leak maintenance does not just end with the pipes. It’s also necessary to monitor all components along a system to ensure that no air is leaked throughout the process. Other parts that should regularly be checked include the valves, connections and fittings. However, air–leak maintenance can only be truly effective at stemming excess costs if the compressor controls and air delivery parts are also functioning correctly.
Ignoring Pressure Loss in the Piping System
One major problem that emerges in compressed air systems is pressure drop, which is marked by a loss of pressure between the compressor and the end point. While a certain amount of pressure drop is inevitable, it should never amount to more than a 10 percent loss of pressure during a given application. Otherwise, higher pressure demands end up being placed on the compressor, which results in more rapid wear and tear across the entirety of an air system.
For each pound of pressure either increased or decreased, a power plus or minus 0.5 percent is required. For example, a five percent power savings can be gained with a decrease of 10 psig. On a 100 hp compressor, this would translate to $1,740 in annual energy savings.
Pressure drop is usually caused by trouble with the pipes and weaknesses at the filters and dryers. Unfortunately, system operators will often compensate for the pressure loss by boosting the system pressure, which results in costlier operations. The correct way to handle this issue is to check for problems at the filters and dryers and replace certain items as necessary.
Failure to Remove Pipe Contamination
It’s crucial for air system pipes to remain clean and free of dirt, rust or other contaminants. After all, compressed air reaches its end point through these pipes. When contaminants are present, air pressure weakens, and the problem gradually accelerates when left un–rectified. The pipes should always remove air from the top of the air line, otherwise contaminants will travel to the pneumatic tools.
Airstream contamination increases with velocity, which in turn increases with restrictions in pipe size. Basically, the velocity of the pipes that run to the end point should be 50 seconds or less, while the interconnecting pipes and main headers should have velocity in the range of 20 to 30 feet per second. System velocity can be calculated by dividing the flow in cfm by the pipe’s compression ratio, divided by the pipe area, divided by 60.
Failure to Manage Condensation
Poor condensation management can lead to numerous problems with a compressed air system. Condensation emerges during the cooling process as moisture is sucked from the air. As the droplets build up within the interior of an air compressor, the following problems are liable to emerge:
- loss of lubrication in the pneumatic tools as condensate washes oil away
- inconsistent quality of air at the end point
- air distributes with excess amounts of rust or scale
- water accumulates within the machine and ruins the circuitry
Additionally, condensation can overload in the air dryers and ruin the in–line filters. The problems with condensation are often especially pronounced in rotary screw air compressors, where the compressor oil will sometimes spread into the air system when mixed with the condensate. The combination of oil and water can lead to dirt deposits that ultimately clog the drains and pneumatic tools.
Another factor that can impact condensation is the ambient temperature that surrounds a facility. Simply put, condensation levels multiply as temperatures rise from average to humid. For example, a 200 hp compressor will produce roughly 50 gallons of condensate over the course of a 60–degree day. However, that same machine will generate more than five times the amount of condensate if the temperature is 30 degrees higher.
Further inefficiency can stem from problems with the system drains, which are designed to deal with condensation. Drains are placed at strategic points along an air compressor system, such as the tank, dryer and aftercooler. The trouble emerges when the drain fails to do its job properly, and sludge accumulates along the drainage points from a mix of water, oil and dirt.
System operators will often expect the drains to handle such issues automatically, but this is a big mistake. Condensation can lead to a huge waste of system resources if the issues that lead to condensation are not monitored and rectified on a regular basis.
Failure to Review Air Demand for Individual Departments
In a spread out industrial plant, the compressed air needs for one department could differ from the others. While the pressure requirements could be at one uniform level across most of the facility, higher pressure may in fact be needed for that one department. Pressure inevitably gets wasted, however, when the entire air system is ran at a higher pressure just to suit the needs of the one department in question.
At multi–department plants that operate a large number of air compressors, it’s crucial to evaluate the needs of each department to determine if one or more has higher needs than the rest. For the departments that do, smaller compressors should be installed in those areas to meet the exclusive needs of said department. That way, the rest of the plant can operate at a uniform pressure without wasting air pressure.
Failure to Train Air System Staff
At certain facilities, machine operators are less knowledgeable than management personnel of the overall intricacies of an air system. This is problematic when you consider how costs can accumulate annually with just slight amounts of daily inefficiency. Therefore, it’s not sufficient when floor staff are only trained on the basic protocols of machine operation, yet lack a broader understanding of how air compressors work.
The operation and management of an air system necessitates an in–depth knowledge that goes way beyond a simple handiness with the machines. In order for air compressors to be operated efficiently, it’s important for everyone on a team to understand the costs of operation. To that end, all staff should be informed on energy conservation and the relationship between the various components within an air system.
Not Compiling Troubleshooting Data
When you know the behavior of a fully functional air system, it’s easier to spot the emergence of problem issues before they spiral out of hand. Some of the worst problems with an air conditioner will start slowly and gradually lead to more costly issues down the line, yet time and money can be saved when such issues are identified sooner. Trouble is, the management at certain facilities fail to record and evaluate data on system operations. Without that knowledge, it’s hard to spot inconsistencies in system patterns.
The secret here is to collect data on system performance on a regular basis to determine the range of behaviors that characterize a fully functional air system within a given setting. Readings should be taken at various points along the system, including the compressors, aftercoolers, receivers, filters and pneumatic tools. Once the accepted patterns have been established, deviations in performance can serve as red flags of potential system issues. Most importantly, information should be gathered of how a compressor normally operates at full load.
The foremost sign of trouble is when temperatures increase beyond the established level within an air system. When temperatures are monitored over time, a baseline can be established that makes it easier to spot deviations. An easy way to read such data is with the use of an infrared thermometer, which gathers data piece by piece when directed at each component along an air system. While this only reads surface temperatures, it can still provide useful data for future troubleshooting.
Quincy Scales Industrial offers preventative maintenance plans that will ensure your compressed air systems function at top performance year-round. Contact us today for a FREE energy assessment, and to learn more about our products and services.