Tag: belt

Air Compressors: Maintenance and Optimization

Published on by John BallLeave a comment

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 lifeblood 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, some items may or may not apply.  But please, always check with the manufacturer of your air compressor.

Intake filter: The intake filter is used to clean the air that is being drawn into the air compressor.  Better filtration results in less debris getting 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 compressor motor to operate harder and hotter.

Compressor Oil: This would be for flooded screws and reciprocating compressors that use oil to lubricate the bearings and sleeves in the air pump.  Most systems have an oil sight 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 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 a lot of 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 multi-meter, 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 converter.  These are typically capacitors, and they are designed to keep the direction of three-phase motors going in the correct rotation.  Both types of capacitors can be checked with a multi-meter.

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 lose the required oil level, but it will affect the performance of downstream parts like air dryers and after-coolers.  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 the oil level.

Monthly:

  • Inspect the cooling fins on the air pumps.  Clean if necessary
  • Inspect the 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 un-loader valve
  • Replace compressed air filters
  • Change oil
  • Grease bearings if required

Keeping your air compressor running optimally is very important for pneumatic operations.  But there is much more than an air compressor in your system.  To help, there are steps that can be used on the demand side.  EXAIR created a Webinar – “Optimizing Your Compressed Air System In 6 Simple Steps”.  With this combination, you can keep a healthy compressed air system.  You can always contact an Application Engineer at EXAIR to see how much money can be saved by energy reduction, safety, and monitoring.  

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Image courtesy of Compressor1 – Creative commons license

The Importance Of Air Compressor System Maintenance

Published on by Russ Bowman1 Comment

It should go without saying, but proper operation of anything that has moving parts will depend on how well it’s maintained.  Compressed air systems are certainly no exception; in fact; they’re a critical example of the importance of proper maintenance, for two big reasons:

*Cost: compressed air, “the fourth utility,” is expensive to generate.  And it’s more expensive if it’s generated by a system that’s not operating as efficiently as it could.

*Reliability: Many industrial processes rely on clean or clean & dry air, at the right pressure, being readily available:

  • When a CNC machine trips offline in the middle of making a part because it loses air pressure, it has to be reset.  That means time that tight schedules may not afford, and maybe a wasted part.
  • The speed of pneumatic cylinders and tools are proportional to supply pressure.  Lower pressure means processes take longer.  Loss of pressure means they stop.
  • Dirt & debris in the supply lines will clog tight passages in air operated products.  It’ll foul and scratch cylinder bores.  And if you’re blowing off products to clean them, anything in your air flow is going to get on your products too.

Good news is, the preventive maintenance necessary to ensure optimal performance isn’t all that hard to perform.  If you drive a car, you’re already familiar with most of the basics:

*Filtration: air compressors don’t “make” compressed air, they compress air that already exists…this is called the atmosphere, and, technically, your air compressor is drawing from the very bottom of the “ocean” of air that blankets the planet.  Scientifically speaking, it’s filthy down here.  That’s why your compressor has an inlet/intake filter, and this is your first line of defense. If it’s dirty, your compressor is running harder, and costs you more to operate it.  If it’s damaged, you’re not only letting dirt into your system; you’re letting it foul & damage your compressor.  Just like a car’s intake air filter (which I replace every other time I change the oil,) you need to clean or replace your compressor’s intake air filter on a regular basis as well.

*Moisture removal: another common “impurity” here on the floor of the atmospheric “ocean” is water vapor, or humidity.  This causes rust in iron pipe supply lines (which is why we preach the importance of point-of-use filtration) and will also impact the operation of your compressed air tools & products.

  • Most industrial compressed air systems have a dryer to address this…refrigerated and desiccant are the two most popular types.  Refrigerant systems have coils & filters that need to be kept clean, and leaks are bad news not only for the dryer’s operation, but for the environment.  Desiccant systems almost always have some sort of regeneration cycle, but it’ll have to be replaced sooner or later.  Follow the manufacturer’s recommendations on these.
  • Drain traps in your system collect trace amounts of moisture that even the best dryer systems miss.  These are typically float-operated, and work just fine until one sticks open (which…good news…you can usually hear quite well) or sticks closed (which…bad news…won’t make a sound.)  Check these regularly and, in conjunction with your dryers, will keep your air supply dry.

*Lubrication: the number one cause of rotating equipment failure is loss of lubrication.  Don’t let this happen to you:

  • A lot of today’s electric motors have sealed bearings.  If yours has grease fittings, though, use them per the manufacturer’s directions.  Either way, the first symptom of impending bearing failure is heat.  This is a GREAT way to use an infrared heat gun.  You’re still going to have to fix it, but if you know it’s coming, you at least get to say when.
  • Oil-free compressors have been around for years, and are very popular in industries where oil contamination is an unacceptable risk (paint makers, I’m looking at you.)  In oiled compressors, though, the oil not only lubricates the moving parts; it also serves as a seal, and heat removal medium for the compression cycle.  Change the oil as directed, with the exact type of oil the manufacturer calls out.  This is not only key to proper operation, but the validity of your warranty as well.

*Cooling:  the larger the system, the more likely there’s a cooler installed.  For systems with water-cooled heat exchangers, the water quality…and chemistry…is critical.  pH and TDS (Total Dissolved Solids) should be checked regularly to determine if chemical additives, or flushing, are necessary.

*Belts & couplings: these transmit the power of the motor to the compressor, and you will not have compressed air without them, period.  Check their alignment, condition, and tension (belts only) as specified by the manufacturer.  Keeping spares on hand isn’t a bad idea either.

Optimal performance of your compressed air products literally starts with your compressor system.  Proper preventive maintenance is key to maximizing it.  Sooner or later, you’re going to have to shut down any system to replace a moving (or wear) part.  With a sound preventive maintenance plan in place, you have a good chance of getting to say when.

If you’d like to talk about other ways to optimize the performance of your compressed air system,  give me a call.

Russ Bowman
Application Engineer
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Image courtesy of U.S. Naval Forces Central Command/U.S. Fifth Fleet, Creative Commons License