Compressed Air System Maintenance

Air Compressor and Storage Tanks

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

Basics of the Compressor Room

EXAIR Corporation has staked our reputation on a keen ability to help you get the most out of your compressed air system since 1983.  Now, the bulk of our expertise lies in the implementation and proper use of engineered products on the demand side, but we fully recognize that there are critical elements for optimization on the supply side too.  And that, quite literally, starts in the compressor room.  This is not an exhaustive, specifically detailed list, but here are some you might consider to get the most from the (again, quite literally) beginning:

  • Location.  If you’re building a new facility, or doing a major rehab of your existing one, having the compressor room as close as practical to the point(s) of use is best, IF all other things are equal.  You’ll use less pipe if you don’t have to run it so far.  You’ll also be able to use smaller diameter lines because you won’t have to worry about line loss (pressure drop due to friction as the air flows through the total length) as much.
  • Location part 2.  If all other things are NOT equal, having the compressor room close to the point of use may not be best for you.
    • Your air compressor pulls in air from the immediate environment.  It’s better to go with longer and bigger pipe in your distribution system than it is to put your compressor in a location where it’ll pull in dust & particulate from grinding operations, humidity from a boiler plant, fumes from chemical production, etc.
    • There are some pretty darn quiet air compressors out there, but there are some pretty loud ones too.  Especially in small to mid size facilities, putting the compressor in an area that upsizes the required piping is still likely a better idea, due to the downsizing of the noise levels that personnel will be exposed to.
  • Environment.  No matter where your compressor is located, the machine itself should be protected from heat and other harsh environmental elements.  That means if it’s inside the plant, the compressor room should be adequately ventilated.  In some situations, the compressor may be best installed outside the plant, in its own building or protective structure.  This should be designed to protect against solar load…in addition to the high temperature associated with a hot summer day, the sun’s rays beating down on your air compressor will radiate a tremendous amount of heat into it.
  • Filtration.  Whatever is in the air in your compressor room is going to get into your compressed air.  This is doubly problematic: particulate debris can damage the air compressor’s moving parts, and it can likewise damage your pneumatic cylinders, actuators, tools, motors, etc. as well.  Make sure the intake of your compressor is adequately filtered.
  • Maintenance.  Air compressors, like any machinery with moving parts, require periodic preventive maintenance, and corrective maintenance when something inevitably breaks down.  There should be adequate space factored in to your compressor room’s layout for this.  The only thing worse than having to fix something is not having the room to fix it without taking other stuff apart.
Patrick Duff, a production equipment mechanic with the 76th Maintenance Group, takes meter readings of the oil pressure and temperature, cooling water temperature and the output temperature on one of two 1,750 horsepower compressors. Each compressor is capable of producing 4,500 cubic feet of air at 300 psi. The shop also has a 3,000 horsepower compressor that produces 9,000 cubic feet of air at 300 psi. By matching output to the load required, the shop is able to shut down compressors as needed, resulting in energy savings to the base. (Air Force photo by Ron Mullan)

These are a few things to consider on the supply end.  If you’d like to talk about how to get the most out of your compressed air system, EXAIR is keen on that.  Give us a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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