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
