Performing regular maintenance on your compressor system helps to keep everything operating in peak condition and ensures you’re not wasting unnecessary energy. Just as you perform regular routine maintenance on your vehicles, a compressed air system also needs a little TLC to keep things running smoothly. Neglected maintenance items can lead to increased energy costs, high operating temperatures, and coolant carryover. Much of these issues can be eliminated simply by performing routine maintenance on the components of the system.
According to the Best Practices for Compressed Air Systems by the Compressed Air Challenge (1), components within the system that need maintained include: the compressor, heat exchanger surfaces, lubricant, lubricant filter, air inlet filter, motors, belts, and air/oil separators.
The compressor and all surfaces of the heat exchanger need to be kept clean and free of contaminants. When these components are dirty, compressor efficiency is greatly reduced. Any fans and water pumps should also be regularly inspected to ensure that they’re functioning properly. The air inlet filter and piping should also be cleaned. The quality of the air in the facility will impact the frequency, refer to the manufacturer’s specifications for ideal intervals for performing scheduled maintenance.
The lubricant and lubricant filter must also be changed per manufacturer’s specifications. Old coolant can become corrosive, impacting useful life and damaging other components while reducing efficiency. While synthetic lubricants are available that have an extended life compared to standard coolants, this does not extend the life of the lubricant filter itself.
Belts should be routinely checked for tension (every 400 hours is reasonable) to alleviate bearing wear. Belts will stretch and wear under normal operation and must be adjusted periodically. It’s a good practice to keep some spares on hand in the event of a failure.
End use filters, regulators, and lubricators should also be periodically inspected and filter elements replaced as needed. If left unchecked, a clogged filter will increase pressure drop. This can cause both a reduction of pressure at the point of use or an increase in the pressure supplied by the compressor, leading to increased energy costs.
Another often overlooked maintenance item is leak detection and repair. Leaks contribute to unnecessary air usage, pressure drop, and increased energy costs. EXAIR offers an Ultrasonic Leak Detector that can be used to identify the leaks in your system and allow you to make the necessary repairs.
EXAIR Ultrasonic Leak Detector
In order to keep your system running in peak condition, regular maintenance is critical. By paying close attention to the manufacture’s recommendations, and implementing a regular maintenance schedule, you can ensure you’re getting the most out of your system components.
To fully appreciate how impactful a properly functioning air compressor system is to your bottom line, it is foremost important to fully understand how much your compressed air costs. Compressed air is a self generated utility within your facility that is a top 3-4 utility expense for your company. This fact is often overlooked or misunderstood, because the expense is primarily linked to the electric and or gas bill. This can be a costly oversite. You will see an example below where a single common maintenance issue causes a 4psi reduction in performance and resulted in $1265 in additional annual cost to that company. Imagine when/if there are multiple issues…
In order to calculate the compressed air cost, some companies use an educated guess of @$0.25 per 1000 cubic feet of compressed air consumed, and others are more precise. The U.S. department of Energy performed an energy saving study in 2004 and they show a precise way to calculate your compressed air cost. Here is their sample calculation:
“Compressed air is one of the most expensive sources of energy in a plant. The overall efficiency of a typical compressed air system can be as low as 10%-15%. For example, to operate a 1-horsepower (hp) air motor at 100 pounds per square inch gauge (psig), approximately 7-8 hp of electrical power is supplied to the air compressor. To calculate the cost of compressed air in your facility, use the formula shown below:
Cost ($) = (bhp) x (0.746) x (# of operating hours) x ($/kWh) x (% time) x (% full-load bhp) ÷ Motor Efficiency Where: bhp = Motor full-load horsepower (frequently higher than the motor nameplate horsepower—check equipment specification) 0.746 = conversion between hp and kW Percent time = percentage of time running at this operating level Percent full-load bhp = bhp as percentage of full-load bhp at this operating level Motor efficiency = motor efficiency at this operating level Example: A typical manufacturing facility has a 200-hp compressor (which requires 215 bhp) that operates for 6800 hours annually. It is fully loaded 85% of the time (motor efficiency = .95) and unloaded the rest of the time (25% full-load bhp and motor efficiency = .90). The aggregate electric rate is 0.05/kWh. Cost when fully loaded = (215 bhp) x (0.746) x (6800 hrs) x ($0.05/kWh) x (0.85) x (1.0) = $48,792 .95 Cost when unloaded = (215 bhp) x (0.746) x (6800 hrs) x ($0.05/kWh) x (0.15) x (0.25) = $2,272 .90 Annual energy cost = $48,792 + $2,272 = $51,064″
I encourage you to calculate this self generated utility cost for your facility. Also keep in mind that this example is using $0.05/kWh, this example was form 2004, today the average industrial sector cost in the US is $0.0747 (see more here). This annual cost puts so many things into perspective. First and foremost the importance of Maintenance. Even more specific, the preventative maintenance costs become much lower than the impact of even one small oversite. Here is an example from the Department of Energy that discusses a specific and common maintenance issue and it’s annual impact.
“A compressed air system that is served by a 100-horsepower (hp) compressor operating continuously at a cost of $0.08/kWh has annual energy costs of $63,232. With a dirty coalescing filter (not changed at regular intervals), the pressure drop across the filter could increase to as much as 6 psi, vs. 2 psi when clean. The pressure drop of 4 psi accounts for 2% of the system’s annual compressed air energy costs. (or an increase of $1,265 per year)”
The realization of the dollars spent for compressed air certainly pushes the priority of maintenance. If we extrapolate from the above filter example, we can see that a 4 psi pressure drop in that system increased the cost by $1265 per year. We need to then ask ourselves, what other areas could be causing a pressure drop or stressing the motor? And if there is an issue upstream to this issue, will it cause even more issues, or more pressure drops?
There are many tips, tools, websites, YouTube videos and more, out there that address the recommended maintenance of your compressor and system. Many of you already have specific guidelines for your precise system, and set maintenance schedules in place. Below is a sample checklist (not all-inclusive) of maintenance items to watch for with your compressor in case you need a starting point. If left unchecked and or uncorrected, any of these (if an issue) will cost your company money – over time, lots of money.
I would be amiss if I finished this blog without mentioning the perils of pressure leaks. The Compressed Air and Gas Institute stated that a single 1/4″ leak, can cost you between $2500 and $8000 per year (CAGI article). Imagine the impact of several leaks!!!
How do I find leaks? I’m glad you asked. The first step is to walk your lines and check any or all of the following areas for leaks or damage.
A great way to identify leaks is to use our Ultrasonic Leak Detector to listen for leaks. Look for and ask the technicians if there seems to be a change in productivity. Install Pressure Regulators and gauges at each point of use in your facility – monitor and log these pressures often. Once you find an issue, no matter how small, correct it. A small leak adds up $$$ over the hours, weeks, and months.
In addition to leaks, there are many times that air is wasted by being blown on empty space (i.e. the space between items on your conveyor). you, please look at our Electronic Flow Control (EFC) product, this device gives you an out of the box automation solution that can be set up in minutes and save thousands. There are so many clogged and leaking pipes, bad hoses inside many plants, this coupled with using an poor performing Air Gun, or Air Nozzle all have large dollar impacts for your company. EXAIR has products that can help in all of these areas…
In parting, please keep in mind that many Utility companies offer incentives to companies that take an initiative to reduce their energy footprint. In our current time of inflation this is a real way to reduce costs, many times significantly. We are here to help. Please contact us for assistance in dramatically reducing both your utility costs, and your environmental impact.
In one of my previous jobs, I was responsible for the operation of the facility, and one of my biggest jobs was the operation of our air compressor. Like with many industries, the compressor system is the life blood of the company. If the compressor fails, the whole facility will stop. In this blog, I will share some maintenance items and schedules for air compressors.
Because the cost to make compressed air is expensive, the compressed air system is considered to be a fourth utility. With such an important investment, you would like to keep it operating as long and efficiently as possible. To do this, it is recommended to get your air compressor a “checkup” every so often. I will cover some important items to check. Depending on the size and type of air compressor, some items may or may not apply. It is always best to check with the manufacturer.
Intake filter: The intake filter is used to clean the air that is being drawn into the air compressor. The better the filtration, the less debris that will get into your system. Particles can damage the air pump mechanisms over time as well as plug filters and heat exchangers downstream. If they are not properly monitored and cleaned, the air flow can be restricted. This will cause the motor to operate harder and hotter.
Compressor Oil: This would be for flooded screws and reciprocating compressor that use oil to lubricate the bearings and sleeves in the air pump. Most systems have an oil sight gage to verify levels. The oil can also be checked for acidity which will tell the degree at which the oil is breaking down. Just like the motor oil in your car, you will have to replace it out after so many hours of operation.
Belts & couplings: These items transmit the power from the motor to the air pump. Check their alignment, condition, and tension (belts only) as specified by the manufacturer. You should have spares on hand in case of any failures.
Electric Motors: A mechanical device that turns electric energy into rotational energy. It is the main component that uses much energy to make compressed air. So, some checks are required to foresee any potential issues and major shutdowns. For the windings inside, the resistance should be measured with a multimeter, and it should fall within the motor’s specifications. Another check should be on the start capacitor. The start capacitor stores energy to give the motor a powerful boost to get it turning. One other item is the centrifugal switch. Just like the name states, it will disconnect the start capacitor when the motor starts spinning. One other item for large electric motors is the phase convertor. These are typically capacitors, and they are designed to keep the direction of a three-phase motors going in the correct rotation. Both types of capacitors can be checked with a multimeter.
Air/Oil Separators: This filter removes as much oil from the compressed air before it travels downstream. It returns the oil back to the sump of the air compressor. If the Air/Oil Separator builds too much pressure drop, excess oil can travel downstream. Not only will the air pump loose the required oil level, but it will affect the performance of downstream parts like your air dryer and after cooler. Also, the pressure drop is a waste and can rob your air system of workable energy.
Internal filters: Many air compressors will come with an attached refrigerated air dryer. With this type of air compressor, they will place coalescing filters to remove any residual oil. These filters should be checked for pressure drop. If the pressure drop gets too high, then it will rob your compressed air system of pressure, and you will not get the required performance. Some filters come with a pressure drop indicator which can help you to determine the time to change the element.
Unloader valve: When the air compressor unloads, this valve helps to remove any of the compressed air that is trapped in the cavity. When the air compressor restarts, it does not have to “work” against this air pressure. If they do not fully unload, the air compressor will have to work harder to start, wasting energy.
Preventative maintenance is very important. As for a schedule, I created a rough sequence to check, change, or clean certain items that are important to your air compressor. You should also check with your local compressor representative for a more detailed maintenance schedule.
Daily:
After stopping, remove any condensate from the receiver tank.
Check oil level.
Monthly:
Inspect cooling fins on air pump. Clean if necessary
Inspect oil cooler. Clean if necessary
Quarterly:
Inspect the inlet air filter. Clean or replace if necessary.
Check the belt for tension and cracks. Tighten or replace.
Check differential pressure indicators on outlet compressed air filters.
Ohm check on the electric motor
Yearly:
Replace Air Inlet Filter
Replace the air-oil separator
Test safety valves and unloader valve
Replace compressed air filters
Change oil
Grease bearings if required
Keeping your air compressor running optimal is very important for pneumatic operations and energy savings. To help your air compressor, you should also check your pneumatic system for optimization. EXAIR manufactures engineered products that can blow, coat, clean, and cool at reduced air consumption rates; saving you money. As an example, the model 1102 Mini Super Air Nozzle can save your company $1,872.00 per year for one blow-off device by replacing a 1/8” NPT open pipe. You can contact an Application Engineer to determine how much EXAIR products can save your company and your air compressor.
Compressed air is the life blood of a manufacturing plant, and the air compressor would be considered the heart. To keep things “fit”, it is important to check all areas and to optimize your system to keep your plant running safely and efficiently. You do not have to be a doctor to do these “operations”. If your compressor fails, the entire facility will stop working. In this blog, I will cover some simple preventative maintenance that can really help you.
As margins get tighter and cost of manufacturing climbs, industries are looking into other areas to be more economical. A big focus today is the compressed air system. Compressed air is considered to be a “forth” utility behind gas, water, and electricity, and it is a necessary to run your pneumatic systems. But it is the least efficient of the utilities. So, it is very important to use this utility as practical as possible and to use a PM program to keep it going.
If we start at the beginning of your compressed air system, this would jump us to the air compressor. This is the machine that uses an electric or gas motor to spin a crank. It compresses the ambient air into a small volume to generate stored energy to be used by your pneumatic systems. Because the air compressor is complex and intricate, I would recommend a trained service personnel to do the maintenance. But, if your staff is familiar with air compressors, I wrote a blog to help look at certain parts periodically. You can read it here: “6 Basic Steps for Good Air Compressor Maintenance (And When to Do Them)”.
The next part after the air compressor is to look at the aftercoolers, compressed air dryers, receiver tanks, filters, and condensate drains. Some facilities may only have some of these items.
The aftercoolers are designed to cool the exit air from your air compressor. It uses a fan to blow ambient air across coils to lower the compressed air temperature. It is easy to check the fan to verify that it is spinning and to keep the coils clean from debris.
The compressed air dryers can range in size and type. For the refrigerant type air dryers, you should periodically check the freon compressor with ohm and amp readings, the condensers for cleaning, and the super heat temperature as well. For desiccant type air dryers, you will need to check the operation of the valves. Valves are used to regenerate one side of the desiccant bed. The valves can fail and stick either open or closed. In either way, if the desiccant cannot regenerate, then it will allow moisture to go down stream and eventually destroy the desiccant beads.
The receiver tanks have safety relief valves that will need to be checked to make sure that they are not leaking. If they are, they should be changed.
As for the filters, they collect contamination from the compressed air stream. This will include liquid water, oil, and dirt. A pressure drop will start to increase with the contaminants, which will reduce the potential energy. If they do not have pressure drop indicators, you should have two points of references for pressure readings. You should change the filter elements when the pressure drop reaches 10 PSID (0.7 bar) or after 1 year.
With all these items above, water is created. There should be condensate drains to discard the water. The most efficient types of condensate drains are the zero loss drains. Most condensate drains will have a test button to be pressed to verify that they open. If they do not open, they should be replaced or fixed. Do not place a valve on them and partially open for draining. For float type drains, they will have a pin inside that can be pressed to open. You can verify that all the liquid has been expelled.
The distribution system are the pipes and tubes that run compressed air from the supply side to the demand side of your pneumatic system. One of the largest problems affecting the distribution system are leaks. That quiet little hissing sound from the pipe lines is costing your company much money. A study was conducted by a university to determine the percentage of air leaks in a typical manufacturing plant. In a poorly maintained system, they found on average of 30% of the compressor capacity is lost through air leaks.
To put a dollar value on it, a leak that you cannot physically hear can cost you as much as $130/year. That is just for one inaudible leak in hundreds of feet of compressed air lines. Unlike a hydraulic system, compressed air is clean; so, leaks will not appear at the source. So, you have to find them by some other means.
Digital Flowmeter
EXAIR Ultrasonic Leak Detector
Most leaks occur where you have threaded fittings, connections, hoses, and pneumatic components like valves, regulators, and drains. EXAIR has two products in our Optimization product line that are designed to help find leaks in your compressed air system.
The Ultrasonic Leak Detectors can find air leaks, and the Digital Flowmeters can monitor your system for loss of air. When an air leaks occur, it emits an ultrasonic noise caused by turbulence. These ultrasonic noises can be at a frequency above audible hearing for human. The EXAIR Ultrasonic Leak Detector can pick up these high frequencies to make inaudible leaks audible.
With the Digital Flowmeters, you can continuously check your system for waste and record it with a USB Datalogger. Air leaks can occur at any time within any section of your pneumatic system. With a Digital Flowmeter, you can also isolate an area to watch for any flow readings; telling you that the air is leaking in that section. With both products included in your leak-preventative program, you will be able to reduce your waste and optimize your compressed air system.
Family of Nozzles
At the point-of-use areas, this is the easiest target area for compressed air maintenance. If you are using open tubes or drilled pipes for blowing, they are loud, inefficient, and unsafe. They can be easily change to an engineered blow-off product from EXAIR which are very efficient and OSHA safe. EXAIR offers a range of Super Air Nozzles and Super Air Knives to simply replace the current blow-off devices that overuse compressed air. If we go back to the beginning of your system, the air compressor is a mechanical device which will have a MTBF, or Mean Time Between Failures. The hour meter on your air compressor is like a life monitor. By using less compressed air, your air compressor will extend that time in MTBF.
Keeping your compressed air system running optimally is very important for a business to run. With a simple maintenance program, it can help you with your pneumatic operations and energy savings. Like stated above, your compressed air system is the life blood of your company, and you do not need a PhD to keep it well maintained. Just follow the target areas above. If you would like to discuss further about the health of your compressed air system, you can contact an Application Engineer at EXAIR. We will be happy to help “diagnose” a solution.
John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb
