Industrial Air Compressor Preventative Maintenance and Common Mistakes

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When it comes to your industrial air compressor, standard maintenance is simply not enough. To make sure things continue to run smoothly and avoid unexpected downtime, it’s crucial to have an air compressor maintenance program that prevents — rather than reacts to — problems with the air compressor and its components.

Unfortunately, air compressor maintenance mistakes are often made by operators who’ve only familiarized themselves with the basic workings of the equipment. Common mistakes in compressed air maintenance include failure to assess energy costs and the impacts of contamination and condensation. These mistakes alone can lead to inefficiency and parts failure that can result in massive amounts of lost money, energy, and time over the course of a year.

Why Preventive Maintenance?

Preventive maintenance is intended to catch mechanical problems before they spread and lead to costly repairs and system downtime. This type of maintenance includes inspections of all system components, either daily, weekly, monthly, quarterly or on an annual basis — to ensure everything works as it should.

In some cases, preventive maintenance involves low-cost measures that help avoid costlier situations down the line. For example, when you notice a compressor belt has a minor crack, replacing the belt right away helps your company prevent a costlier scenario where the belt snaps, the compressor stops working and productions grind to a halt as you work to identify the problem and take the necessary steps to get the system back up and running.

The Benefits and Value of Preventive Maintenance for Industrial Air Compressor Systems

Regardless of the size or scope of your compressor operation, it is necessary to have someone on staff, or work with a qualified service provider, to oversee preventive maintenance work on a timely and consistent schedule. Only with a preventive maintenance schedule can you ensure the machines will work hour by hour, day after day, and continue to operate to their full life expectancy, and in an efficient manner.

Avoid Downtime
We all know that when the machines fail to function, it halts production. A company that ignores timely maintenance protocols runs the risk of encountering performance issues. And these issues always seem to pop up at the worst possible moments – like when a high-cost production is underway with a set deadline. To be on the safe side, you need to perform air compressor maintenance as scheduled without skipping a date, even on days when everything seems to be running fine.

Save Money by Avoiding Emergency Repairs
Emergencies are costly. Production lines stop, parts require express shipping, and you have employees standing around waiting for the machine to get up and running. With reduced downtime and parts failure in your air compressor system, you save money, profiting through increased productivity and reduced overhead. The money you save through timely air compressor maintenance allows you to invest more in better equipment as innovations reach the market.

Lower Energy Costs
Performing air compressor maintenance on a regular schedule allows you to catch potential issues, like a part that’s over-exerting or struggling to maintain an expected rate of production. When these issues  arise, it’s often a result of a part that needs cleaning, replacement or lubrication. By spotting these problems early on, the machine runs smoother and more efficiently, which means more energy savings.

Energy savings equal money saved in overall production costs so you can invest the money back into your company.

One of the biggest compressed air maintenance mistakes is to underestimate or miscalculate the amount of energy that a compressor will use within a year. The most problematic aspect is the wasteful usage of a compressed air system, which often occurs when operators are unaware of the overall energy costs. To best assure efficiency, it’s important to accurately calculate the annual energy costs of an air compressor, and to make sure that all operating staff understand how the figure plays out on a daily basis. That way, wasteful system use can be curbed going forward.

Increase Air Compressor Life and Efficiency
A huge benefit of air compressor maintenance is that it increases the life and efficiency of the machine itself and the system as a whole. When you add up the initial cost of investment in an air compressor and all the attached components and pneumatic tools, you want to ensure a return on that investment through years of optimal performance. Ideally, the money you spend on your compressor system should reward you thousands and thousands of times over through productivity.

Without maintenance, an air compressor and its peripheral components will not last as long as it otherwise could with regular checkups, tuneups and maintenance. When you compare the profits of companies that implement responsible system maintenance with those that don’t, you’re liable to see major differences in productivity.

Recommended Preventive Air Compressor Maintenance 

Preventive maintenance is crucial to ensure the functionality of the compressed air system and its components. The key parts to check include the filters, vents, belts and bearings, all of which could cause issues if dirt and grime build up. Additionally, you must apply and reapply lubricant at timely intervals on all applicable parts of an air compressor.

Among certain air system operators, it’s simply assumed that maintenance begins and ends with a check of the compressor for signs of condensation and dirt. But, there can be greater consequences for operators who overlook the broader maintenance steps. It’s not unheard to have a set of air compressors that function perfectly, yet still have problems with the overall system.

Even though the compressor is the main component of concern within an air system, it’s not the only one in need of routine maintenance. Of equal importance during any maintenance inspection are the other components that facilitate the air supply. Be certain not to overlook the air receiver, which holds compressed air for times when air demands increase, and also reduces system wear and contamination.

The air receiver makes it possible to run the compressor at lower levels and conserve energy in the process. However, the air receiver won’t be able to do its job properly if it’s too small for the system, because the compressor will have to run longer than necessary to keep up with air demand. Therefore, it’s important to ensure that the air receiver is either large enough for the system, or backed with secondary receivers.

Additional air compressor maintenance issues to consider include:

Ignoring Pressure Loss in the Piping System
A major problem that occurs in compressed air systems is pressure drop, which is a loss of pressure between the compressor and the end point. While some pressure drop is inevitable, it should never amount to more than a 10% loss of pressure during any given application. When this happens, higher pressure demands end up being placed on the compressor, resulting in more rapid wear and tear across the entirety of an air system.

For each pound of pressure either increased or decreased, a power plus or minus 0.5 percent is required. For example, a five percent power savings can be gained with a decrease of 10 psig. On a 100 hp compressor, this would translate to $1,740 in annual energy savings.

Pressure drop is usually caused by trouble with the pipes and weaknesses at the filters and dryers. Unfortunately, system operators will often compensate for the pressure loss by boosting the system pressure, which results in costlier operations. The correct way to handle this issue is to check for problems at the filters and dryers and replace certain items as necessary.

Removing Pipe Contamination
Air system pipes must remain clean and free of dirt, rust or other contaminants. After all, compressed air reaches its end point through these pipes. When contaminants are present in the pipes, air pressure weakens, and the problem gradually accelerates when left unresolved. The pipes should always remove air from the top of the air line, otherwise contaminants will travel to the pneumatic tools.

Airstream contamination increases with velocity, which increases with restrictions in pipe size. The velocity of the pipes that run to the end point should be 50 seconds or less, while the interconnecting pipes and main headers should have velocity in the range of 20 to 30 feet per second. System velocity can be calculated by dividing the flow in cfm by the pipe’s compression ratio, divided by the pipe area, divided by 60.

Managing Condensation
Condensation emerges during the cooling process as moisture is sucked from the air. As the droplets build up within the interior of an air compressor, the following problems can potentially occur:

  • lubrication loss in the pneumatic tools as condensate washes oil away
  • inconsistencies in the quality of air at the end point
  • air distributes with excess amounts of rust or scale
  • water accumulates within the machine, ruining the circuitry

When condensation occurs in the air dryers it can ruin the in–line filters. Problems with condensation are especially noticeable in rotary screw air compressors, where the compressor oil can spread into the air system when mixed with the condensate. The combination of oil and water can lead to dirt deposits that can clog the drains and pneumatic tools.

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Another factor that can impact condensation is the ambient temperature surrounding a facility. Condensation levels multiply as temperatures rise from average to more humid. Meaning a 200 hp compressor will produce approximately 50 gallons of condensate over the course of a 60 degree day. However, that same machine will generate more than five times the amount of condensate if the temperature is 30 degrees higher.

Further inefficiencies can can be created within the system drains, which are designed to deal with condensation. Drains are placed at strategic points along an air compressor system, such as the tank, dryer and aftercooler. Trouble emerges when the drain fails to do its job properly, and sludge accumulates along the drainage points from a mix of water, oil and dirt.

System operators will often expect the drains to handle these issues automatically, but this is a big mistake. Condensation can lead to a huge waste of system resources if the issues that lead to condensation are not monitored and handled regularly.

Cleaning the Air Filter
The purpose of an air compressor is to produce clean, pure, compressed air that will power numerous functions. To ensure good quality of air that comes out at the end, the ambient air that goes into the compressor has to be filtered form impurities before it leaves the machines. None of that is possible without a clean air filter.

If the air filter is dirty, impurities and particulates could corrupt the compressed air and degrade the quality of end-point applications. You must clean the air filter regularly and change it out at regular intervals.

Using Lubricant
Lubricant is one of the most vital elements in the function of an air compressor. Lubricant allows for smooth, non-corrosive movement on all the internal metal parts and joints. Without lubrication, tension occurs between the metal surfaces that touch, leading to the corrosion of parts and joints. Once corrosion begins to takes place, rust is liable to spread and eat through certain mechanical parts.

However, even when lubricant is present, it can lose its viscosity and become corrosive if it gets old. Check the lubricant level daily to ensure the health of your air compressor. Wipe off old lubricant and reapply a fresh coat every three to six months. Each time you replace the lubricant, be sure you also change out the separator element.

Checking the Oil Filter
Oil can degrade the quality of compressed air if it passes through the system and gets carried to the end of an application. Some of the worst-affected processes would include pneumatic spray painters, air cleaners and anything else where oil could corrupt the surface. It’s crucial to ensure that if oil is present in the system, it is removed from the compressed air before the air leaves the machine.

Check oil filters weekly, regardless of whether the compressor is lubricated or not. Replace the oil filter entirely at recommended intervals, which can range from 4,000 to 8,000 hours of use, depending on the unit. If the oil filter gets heavily covered in oily residue before that time, replace it sooner.

Belt Inspection
For an air compressor to function properly, the belts must have proper tension. The rubber of each belt must remain firm, yet flexible, to ensure balanced movement between the pulleys of connected parts. Over time, the rubber on a belt will wear down and crack. Therefore, it’s crucial to replace the belts before they lose their tension or, even worse, snap in the middle of an operation.

Inspect belts once every week to make sure they are free of wear. Adjust the tension if necessary and replace belts that begin to show signs of wear.

Greasing Motor Bearings
For a motor to run, the bearings must have proper lubrication. The tiny metal balls are constantly rolling against each other, and the interior walls of the encasement. Rust can form on bearings that are not properly lubricated. If rust forms, the bearings will gradually slow and ultimately become stuck in place. When this happens, the motor fails.

To protect the health and performance of the air compressor’s motor, grease the bearings every 4,000 hours. Inspect the bearings at quarterly intervals between each greasing to ensure they remain sufficiently lubricated.

Inspect Intake Vents
An air compressor can transform ambient air into something that can power heavy-duty machinery and effectively serve as a replacement for electrical power. That being said, the compressor itself can only do so much to turn mundane air into something powerful. While internal components do their job to purify the air for end-point use, that job is harder for the machine to perform if the intake vents become lined with dirt and grime.

To ensure the incoming air stays as clean as possible, and to prevent dirt from getting sucked into the system, be sure to inspect the intake vents weekly and clean them when necessary.

Other Parts and Things to Check
In addition to the periodic cleaning, lubrication and replacement of parts, check various points along the air compressor and its attachments at regular intervals. You’ll want to inspect the following items on a weekly basis:

  • Air dryer performance
  • Oil level
  • Amps
  • Voltage
  • Temperatures
  • Vibration

Also be sure to inspect the air compressor for signs of oil or air leaks. Check the pneumatic hoses for air leaks, which can severely reduce the efficiency of an air compressor. Furthermore, make sure the coolers are free of dirt.

What’s Included in the Preventive Maintenance Schedule?

When making a preventive maintenance checklist, you have to consider the type of compressor you have, as maintenance schedules will vary.

Air-Cooled Reciprocating Compressor

Daily: Or after eight hours of use

  • Check lubricant levels to make sure they never drop below the mid-range of the bayonet gauge. If the lubricant becomes discolored, empty and refill it.
  • Empty water out of the receiver tank
  • Visually inspect the compressor and verify the safeguards are in place
  • Check for leaks and vibrations

Weekly: Or after 40 hours of use

  • Check pressure relief valves
  • Clean the surfaces of the compressor and intercooler
  • Clean out the air intake filter
  • Inspect the compressor and hoses for air leaks

When the weather is humid or the environment is dusty, perform the preceding steps twice weekly, or every 20 hours.

Monthly: Or after every 160 hours of use, inspect the belt tension inside the air compressor

Quarterly: Or after every 500 hours of use, perform the following steps:

  • Change the lubricant
  • Inspect the lubricant filter, and change the oil filter if applicable
  • Inspect the torque on the pulley nuts and screws

Biannually: Or after every 1,000 hours of use, perform the following steps:

  • Change lubricant — this step also applies if the lubricant is synthetic, which lasts twice as long as regular
  • Check valves for signs of leaks or carbon prints
  • Clean the crankcase
  • Clean the strainer screen of the crankcase
  • Examine the motor-area contact points and pressure switch diaphragm

Lubricant-Injected Rotary Compressor

Daily: Or after every eight hours of use:

  • Monitor all gauges and indicators for normal operation
  • Check for fluid leaks
  • Check fluid levels
  • Observe for unusual noise or vibrations
  • Drain water from air/fluid reservoir

Monthly: Every four weeks, perform the following:

  • Service air filter as needed. This should be a daily or weekly task if extremely dirty conditions exist.
  • Clean aftercooler and fluid cooler fins, for air-cooled units only
  • Wipe entire unit down to maintain appearance

Biannually: Or after every 1,000 hours of use

  • Take fluid sample
  • Change fluid filter
  • Check pressure relief valve

Periodically/Yearly: Complete these tasks each year:

  • Review unit and check tightness of all bolts
  • Change air/fluid separator
  • Lubricate motors
  • Change air filter
  • Test pressure relief valve for proper operation
  • Check safety (HAT) shutdown system

Lubricant-Free Rotary Screw Compressor

Daily: Or after every eight hours of use:

  • Check display readings
  • Check if condensate is discharged during operation
  • Drain condensate manually (when applicable)
  • On compressors with integrated dryer, check the dew point

Every Three Months: Or after 500 hours of running use:

  • Check the pressure drop over the (optional) filters
  • Inspect the air inlet filters: check for cleanness and damage. Replace a dirty or damaged filter with a new one.
  • Check the coolers and clean by air jet if necessary

Biannually: Or after every 1,000 hours of use:

  • Operate the safety valve
  • Clean the compressor
  • On compressors with an integrated dryer, brush or blow the finned surface of the condenser and inspect and clean the electronic drain

Periodically/Yearly: Perform these tasks every year:

  • Replace the air inlet filters
  • Test the safety valves
  • Have temperature protection and motor overload tested
  • Check tension and condition of the V-belts

Every Two Years: Complete the following tasks:

  • Replace V-belt(s)
  • Replace the check valves

Which Maintenance Checks Should a Technician Perform?

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Oftentimes your staff is equipped to handle air compressor preventive maintenance in-house. But one mistake that people often make is that some machine operators are less knowledgeable when it comes to the overall intricacies of an air system. This can cause issues when you consider how costs can accumulate annually with just slight amounts of daily inefficiencies. It’s not sufficient enough when your team is only trained on the basic protocols of machine operation, yet lack a broader understanding of how air compressors work.

The operation and management of an air system requires an in-depth knowledge base that extends beyond a simple handiness with the machines. In order for air compressors to be operated efficiently, it’s important for everyone on the team to understand the costs of operation. To that end, all staff should be informed on energy conservation and the relationship between the various components within an air system.

However, there are some tasks that are better off being performed by a professional — even more so if the unit is large or complicated. Unless your company is staffed with highly skilled personnel to handle air compressor maintenance tasks, it’s best to contact a professional for the following:

  • System safety-shutdown inspections
  • Motor replacement
  • Relocation of large, heavy air compressors
  • When mechanical breakdowns occur
  • When you don’t have qualified staff to work on your compressed air systems

When you hire a professional for these and other time-consuming and potentially dangerous tasks, it can save you time and money, and also ensure that the job is done properly. Professional air compressor maintenance ensures utmost safety for the more difficult aspects of the job.

Making a Compressed Air Preventive Maintenance Plan

To ensure maximum efficiency, minimum downtime, and lower repair costs with your air compressor, follow your preventive maintenance checklist according to schedule. Depending on the needs of a given component, maintenance should be performed daily, weekly, monthly, quarterly or annually.

When you perform preventive maintenance according to a checklist, your air compressor and its components will last longer and perform more efficiently. Preventive maintenance makes it possible to detect problems early on, before they cause serious system damage and lead to costly repairs and downtime. You can invest the money you save with preventive maintenance back into your company’s infrastructure and staff.


Rotary Screw Compressor Troubleshooting Guide

Run more efficiently with this quick reference guide that covers issues such as:

  • Low pressure
  • Excessive vibration
  • Low oil pressure
  • Overheating
  • Excessive oil consumption
  • Excessive current draw
  • Failure to start or motor stalls