Throughout the industrial sector, compressed air is one of the most vital components in the production process. At auto-assembly factories and newspaper pressing plants alike, rotary screw air compressors power assorted applications along the assembly line. Consequently, air compressors experience heavy use and require consistent maintenance. Even a well-maintained air compressor can have issues with its various components, any of which could be symptomatic of a larger problem.

Unfortunately, a lot of compressor operators fail to heed these warning signs, in part because they are unfamiliar with the telltale symptoms. As such, it is important to have an air compressor troubleshooting guide on hand to know how to address specific symptoms, as well as a list of actions to take with each problem.

The functions of a rotary screw compressor are relatively straightforward. A pair of turning screws bring air into the chamber, which tighten the chamber and cause the air pressure to rise in inverse proportion to the volume. Control features set the pressure range according to the needs of an application.

Despite this simple process, the design of these compressors consists of complex parts that can run into trouble in numerous ways. If these problems persist without maintenance, a small problem can metastasize into a costly system failure that ultimately necessitates the replacement of parts. Therefore, it is crucial to know the sounds and visual cues of a failing compressor.

The Top Reasons Air Compressors Fail

A variety of problems can cause a rotary screw air compressor to fail well short of its full life expectancy. Issues such as air leaks, filter clogs and inadequate lubrication can all serve as warning signs of a gradually failing system.

While you should always carry out compressor maintenance according to schedule, the problems associated with system failure can still take root if certain issues and their symptoms go unrecognized. The following issues are the main problems to look for as you proceed with your air compressor troubleshooting efforts.

Air Leaks

Leaks along a system are often the cause of air compressor failure. These leaks can form as parts wear down with age. As cracks form along one of the pipes or hoses, the loss of air can be a slow but gradual process. Little by little, the crack will render your system far less efficient.

When a leak becomes large, it might become an audible problem that isn’t too difficult to trace if you follow the noise. In a lot of cases, however, it takes ultrasonic equipment to isolate the source of the problem. In any case, air leaks can be a costly problem due to the lost productivity that results from decreased volumes of compressed air in a given set of operations.

Exceeded Pressure Limits

Compressor failure is also often the result of excess pressure. When system operators run compressors at pressure levels beyond the recommended limits, the effect of this excess pressure puts undue strain on system components. Basically, air compressors have their limits for a reason.

Pressure limits can get exceeded when a single air compressor conducts too many simultaneous operations. If you are using a small machine to handle a multitude of high-powered tasks, you are liable to shorten the life of the air compressor. While it might seem as though you are saving money by overworking one air compressor, you might actually save in the long run by investing in a second compressor and evening out the workloads.

The costs associated with excess pressure levels can be financially draining in several ways, as excess pressure leads to wasteful energy usage, shortened service intervals, increased occurrences of downtime and earlier compressor failure.

Clogged Air Filters

The air filters are among the most important components of a compressed-air system. If not for the air filters, the compressed air your system generates would get corrupted with dust and dirt as it travels to each endpoint application. However, air filters themselves get dirty and need frequent monitoring.

As dirt and dust collect on the air filters, impurities move through the system and degrade the quality of compressed air. Moreover, dirty air filters impede system performance and force the system to exert more energy just to perform basic functions. If the problem persists, dirty air filters can lead to excess energy consumption, costly maintenance and downtime. Rotary screw air compressor overheating is also sometimes the result of clogged air filters.

Infrequent Maintenance

Another oversight that can lead to premature compressor failure is insufficient maintenance. If you have not established a maintenance schedule for your air compressor and its assorted attachments, issues could easily emerge that are liable to spread before they even come to your attention. In some cases, the issues might start from simple problems you could easily rectify in minutes during a routine checkup.

For example, you can remedy the buildup of dirt and the gradual wear-down of system resources with daily inspections of the filters and valves. At times when nobody is using the system, make sure to turn off the compressor and close it at the valves. Moreover, you should monitor system noises regularly to ensure no irregular patterns emerge. It’s a best practice to establish a day of the week or month for each area of system maintenance.

Insufficient Lubrication

As with motor vehicles, air compressors need sufficient oiling and lubrication to function as intended. Some of the most common causes of compressor failure are irregular oil changes and negligent lubrication intervals. When you fail to lubricate the internal components of an air compressor sufficiently, friction occurs between the metal surfaces.

As lubrication ages, it loses its viscosity due to prolonged exposure to heating and cooling cycles. If the working environment becomes excessively humid, grease can liquefy and lose its ability to lubricate the moving parts properly. Likewise, if extremely cold temperatures permeate the workspace, the lubricant can become icy and ineffective. Alternatively, if you leave a lubricant to age beyond its usefulness, its properties can become acidic and have a varnishing, corrosive effect on the interior parts.

When you replace the oil and lubrication in your air compressor, it is important to remove the old oil. When old and new oils mix, the former can degrade the latter’s quality. For example, when you refill a dirty oil tank, the acidity of the older oil that lines the interior can corrupt the new oil supply and reduce its freshness. Soon enough, the problems associated with old oil will resurface. A similar effect can occur when you apply fresh lube over old, hardened lubricant.

Dirty Air/Oil Separator

For compressed air to be clean and pure when it reaches the endpoint, oil from the system needs to be filtered out before the air leaves the machine and travels through the hoses. Oily compressed air can seriously degrade the quality of pneumatic operations such as sanding, spray painting and air drying.

The component that prevents compressed air from becoming saturated with oil mist is the air/oil separator, which extracts oil from the air before the latter leaves the compressor. However, the air/oil separator can only hold so much oily buildup, which can ultimately spread to adjacent parts and have a detrimental effect on the system as a whole. Therefore, you need to change out the air/oil separator periodically, preferably after 800 hours of use.

A Faulty Airend

The screw component of a rotary compressor — alternately called the pump or airend — is the principal piece of the system’s functionality. However, the pump can wear down and require maintenance long before it reaches the end of its life expectancy. Therefore, screw compressor troubleshooting is often necessary in this area.

Issues that can lead to pump failure include overheating and excess system pressure. If condensation buildup persists within the machine, the effects of the moisture can be detrimental to the airend. The impact of vibrations and the effects of oily residue can also wear down on the screw component. When the air compressor lags, stalls or appears defective, this area is often the root of the problem. Signs of an advanced problem include leaks from the oil seal and strange bearing noises.

Drive Train Issues

On belt-driven models, the belts and sheaves should be inspected after every 500 hours of use. Direct-coupled rotary screw models need alignments when the motor and airend are aligned improperly. If alignments are off, motor and airend bearings are liable to wear down and cause the compressor to fail. To ensure proper alignment, it is generally best to contact an air compressor service professional.

Improperly Greased Motor Bearings

The bearings in the compressor motor make the system operate. Sufficient amounts of grease applied periodically help the bearings move around smoothly. If the grease amount is insufficient, the bearings are liable to cause friction between one another and degrade the performance of the motor overall.

To ensure proper health of the motor bearings, you must grease them with a lubricant of the proper grade and viscosity. Failure to do so could lead to system overheating, excess energy consumption and premature system failure. Do not mix grades of motor grease or alternately apply them to the bearings, as the properties of each lubricant could come into conflict and have a corrosive effect.

How to Prevent Rotary Screw Compressor Failure

Air compressor problems are easiest to remedy when you catch them at an early stage. Nonetheless, you can rectify even the more advanced problems if you follow a rotary screw troubleshooting guide and service or replace the affected parts.

That said, you should read any symptom associated with air compressor failure as a warning sign to shut down the system and service it immediately. Failure to act now could ultimately prove to be a costly mistake down the line. Therefore, you should have an air compressor troubleshooting chart available with a list of actions to perform for each of the following pre-failure symptoms.

Air Compressor Fails to Start

If you press the power button and the compressor fails to activate, the problem will typically be down to an electrical issue. In some cases, the machine will have tripped on a safety device. Either way, the first thing to do is check for the following errors:
  • Disconnected power supply
  • Errors on the display
  • Failed emergency stop

Inspect the overload relay and reset if necessary. There might be an issue with the phase sequence if the installation was recent. In any case, it is always best to inspect for simple problems before you consider the possibility of more serious issues.

Compressor Powers off at High Temperatures

If your compressor shuts down abruptly as it reaches a certain temperature, the problem is likely due to one of the following issues:
  • Overbearing ambient temperature
  • Poorly ventilated workspace
  • Incorrect oil type
  • Dirty oil cooler
  • Malfunctioning thermostatic valve
  • Blocked/dirty oil lines

The biggest cause of compressor burnout is overheating, which can occur when there is too much humid air trapped in the work area, especially on compressors with obstructed vents. If the machine is up against a wall and the vents lack breathing space, consider moving the compressor to a better-ventilated area. Also, check the oil and clean out the cooler and oil lines if necessary. If oil corrodes and loses its proper viscosity, internal machine parts will start to grind, cause friction and overheating.

Compressor Runs but Fails to Load

Rotary screw compressors run in two load modes — the loaded, or “pumping air” mode, and the unloaded, or “idle” mode. Depending on air demand, the inlet valve through which air loads will either open or close. The solenoid valve supplies this same valve with controlled air. If the compressor fails to load, inspect the following:
  • The solenoid valve power source
  • The solenoid valve coil
  • The solenoid valve performance
  • The inlet valve performance

Make sure the solenoid valve receives power, and that both the solenoid and inlet valves perform free of obstructions.

Insufficient Pressure

If your air compressor generates air pressure at low capacity, check the current air demand. In some cases, the demands of assorted tools are too low to merit normal pressure levels. Also check for the possibility of a leak somewhere along the compressed air system. If the air pressure is indeed insufficient for your current round of operations, perform the following steps:
  • Inspect the inlet valve for obstructions.
  • Inspect the inlet filter for dust or dirt.
  • Inspect the condition of the air filters.
  • Inspect the oil separator.

Replace the air filters and oil separator if necessary. Clean the inlet filter as needed and make sure the valve is fully open.

Safety Valve Fails

If the compressor fails to unload, inspect the pressure switch to ensure it functions properly at the correct setting. Also, inspect the performance of the inlet and solenoid valves. If the oil separator is after the safety valve, inspect the former’s differential pressure.

Compressed Air Saturated With Oil

If any trace of oil gets past the separator, it can degrade the quality of your endpoint applications. When oil does saturate the compressed air, the problem is typically down to one of the following issues:
  • A spent, dirty oil separator
  • A clogged scavenge line
  • Operating temperature is too hot
  • Oil level is excessively high
  • The oil type is ill-suited to the compressor
  • The minimum pressure valve is malfunctioning

If the oil separator is old and dirty, change it out for a new one. If the oil has thinned out, change to a more appropriate brand of proper viscosity.

Moisture in Compressed Air

Water particulates comprise a portion of all ambient and compressed air. As such, there is no way to guarantee compressed air with zero moisture content. That said, a properly functioning compressor should keep the water content down to a minimum level.

If water content rises at the expense of endpoint functions, inspect the condensate trap. Does it appear to trap water at normal levels? Every couple of minutes, water should come out. When you use the manual drain, little, if any, water should come out. If your system includes an air dryer, make sure the dewpoint is ideal.

Failure of the Overload Relay

If the overload relay trips, inspect the current draw and clamp meter on your air compressor. If the motor draws excessive current levels, perform the following steps:
  • Physically turn the compressor, but only with the power off.
  • Inspect the isolation of the motor windings.
  • Check the running-time voltage of the compressor.

Make sure you can turn the compressor without it making hiccup noises. If the voltage plummets each time the compressor is activated, the connection is weak. If overload still causes the compressor to trip despite a normal current, change out the overload relay.

Rotary Screw Compressors From Kaishan Compressor

Rotary screw models see use in a vast range of assembly applications, the results of which are everyday fixtures of contemporary living. From the automobiles and aircraft that fill the world’s roads and airways to the appliances, furnishings and consumable products found on the shelves of every supermarket, companies have used compressed air to mold, attach and fasten product parts and can, bottle, seal and label foods and beverages.

Today’s more eco-conscious world relies on compressed air more than ever as an alternative power source for a variety of high-tech applications, the likes of which would otherwise consume enormous amounts of energy. On this and numerous other fronts, Kaishan Compressor is leading the way by offering air compressors that preserve energy while providing more air per unit of power.

At Kaishan Compressor, we offer a range of rotary screw air compressors, from the 10-50 HP belt-drive KRSB to the 100-500 HP two-stage KRSP 2. We back the main screw airend component with a lifetime warranty, while we offer a five-year warranty on the other major components.

Whether you run a large or small production facility, compressed air can serve as a vital utility that in many areas could easily supplant the use of electrical power. For numerous processes and assembly tasks, air-powered pneumatic tools and machinery can accomplish levels of productivity at volumes human hands could never match.

Whether you are looking to buy your first compressor or replace an old, outdated model, there are rotary compressors for all demands and tasks in the Kaishan Compressor inventory. Browse our catalog and contact us today for more information on high-quality air compressors.
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