The Importance Of Planned Maintenance

“If it ain’t broke, don’t fix it” is a common phase that we’ve all heard. It’s also a recipe for disaster. Think about it:

  • Corrective maintenance is ALWAYS more expensive. An oil change in your car might set you back $50 and an hour or so, but when (not if) emulsified, contaminated oil causes your engine to seize, that’s a four (if not five) figure repair bill.
  • Corrective maintenance is also ALWAYS more inconvenient. “If you don’t schedule time for maintenance, your equipment will schedule it for you.” ’nuff said.

Anything with moving parts is going to live its best life if you maintain it properly, and your air compressor has a LOT of moving parts that are CONSTANTLY under a good deal of mechanical stress. Your compressor’s manufacturer almost certainly has a published list of recommended maintenance items, with a schedule of when they should be performed. While that list is going to vary, depending on the type of compressor you have, some of the more common items include:

  • Intake Filter: This is what removes environmental contamination from the air that the compressor is drawing in. When (not if) it gets dirty, your compressor works harder. That means higher power consumption, which means higher operating costs. It also means more heat is generated, which can wear machinery out WAY faster than it should.
  • Lubricating Oil: If your compressor is oil lubed, that oil needs to be changed periodically. The schedule for this is always going to be a certain number of hours of operation, or a certain period of time, whichever comes first. That first one is because the amount of particulate contamination is going to be roughly proportional to the amount of time the lubricated parts spend in motion. The latter is because oil just loses some of its critical lubricating properties over time.
  • Drive Equipment: The two main methods of connecting a motor to a compressor are direct drive shaft coupling, or a system of pulleys and belts. Making sure they stay aligned is critical to their operation. Depending on the nature of the drive, lubrication, tension, and physical condition are all important maintenance points as well.
  • Safety (Pressure Relief) Valve: This valve releases excess pressure if the pressure switch fails and the compressor keeps running. At the very least, this keeps your operating costs in line — the higher the discharge pressure, the higher the power consumption. And, worst case, it makes sure you don’t over pressurize the system. If your receiver tank blows up, that’s a bad day.
  • Receiver Tank Condensate Drain: While there are a number of automatic condensate drains available for industrial air compressors, many owners choose to manually drain condensate from the wet receiver. This should be done AT LEAST once a day, with some manufacturers recommending it more frequently than that. This is critical because standing water can corrode the tank from the inside over time. It can also lead to moisture carryover into the header, and it reduces the volume of available air storage in the tank.
  • Keep Clean To Keep Cool: Air compressors generate heat, both from the friction between the moving parts, and the compression itself (Gay-Lussac’s Law states that the pressure of a given mass of gas is directly proportional to its temperature as long as the volume is constant.) Some compressors are air cooled; others are water cooled. Whichever yours is, keep the heat transfer surfaces — like the fins on the air end housing (air cooled) or fins of the heat exchanger (water cooled) — clean & free of debris to maximize the heat transfer, keeping your compressor as cool as possible.

Again, these are just some of the more common maintenance items for an air compressor. If you want yours to live its best life, keep up with the manufacturer’s recommendations. Oftentimes, maintenance records are required for warranty consideration, should something fail. If you have questions about getting the most out of your compressed air system, give me a call.

Russ Bowman, CCASS

Application Engineer
Visit us on the Web
Follow me on Twitter
Like us on Facebook

6 Basic Steps for Good Air Compressor Maintenance (And When to Do Them)

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. (Air Force photo by Ron Mullan)

In one of my previous jobs, I was responsible for the operation of the facility.  One of my biggest responsibilities was the air compressor because it supplied pressurized air though out the facility to feed the pneumatic systems.  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 preventative maintenance items and schedules for your air compressors.

Because the cost to make compressed air is so expensive, compressed air systems are considered to be a fourth utility.  And with any 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 as well as a recommended schedule for checking.  Depending on the size of your air compressors, some items may or may not apply.

1. Intake filter:  The intake filter is used to clean the air that is being drawn into the air compressor.  Particles can damage the air pump mechanisms, so it is important to have the proper filtration level.  But, as the intake filter builds up with debris, the pressure drop will increase.  If they are not properly monitored and cleaned, the air flow will be restricted.  This can cause the motors to operate harder and hotter as well as reduce the efficiency of the air compressor.

2. Compressor Oil:  This would be for flooded screws and reciprocating compressors that use oil to operate the air pump.  Most systems will have an oil sight gauge to verify proper levels.  In larger systems, the oil can be checked for acidity which will tell you the level at which the oil is breaking down.  The oil, like in your car, has to be changed after so many hours of operation.  This is critical to keep the air pump running smoothly without service interruptions.

3. Belts and 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.

4. 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 or gets damaged, excess oil will travel downstream.  Not only will the air pump lose the required oil level, but it will also affect the performance of downstream parts like your air dryer and after cooler.

5. Internal filters:  Some air compressors will come with an attached refrigerated air dryer.   With these types of air compressors, 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 air pressure.  Some filters come with a pressure drop indicator which can help you to determine the life of the internal filter element.

6. Unloader valve:  When an air compressor unloads, this valve will help to remove any compressed air that is trapped in the cavity of the air pump.  So, when the air compressor restarts, it does not have to “work” against this “trapped” air pressure.  If they do not fully unload, the air compressor will have to work much harder to restart, wasting energy.

Preventative maintenance is very important, and checks need to be performed periodically.  As for a schedule, I created a rough sequence to verify, change, or clean certain items that are important to your air compressor.  You can 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.

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 optimally is very important for pneumatic operations and energy savings.  I shared some important information above to assist.  Another area to check would be your pneumatic system downstream of the air compressor.  EXAIR manufactures engineered products that can reduce air consumption rates.  You can contact an Application Engineer to discuss further on how we can save you energy, money, and your air compressor.

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