A Grab Bag Full of FAQs

Oct 21, 2021 by Brad Taylor

Table of contents

Being the air compressors supplier, we often have our customers looking for answers about industrial air compressor maintenance and system design. We’re reaching into the grab bag to answer your top questions.

Don’t see your question answered here? Contact us with any other issues that are on your mind. One of our compressed air system experts will be happy to help!

1. How do I dispose of used air compressor oil?

Air compressor oil is toxic to humans and animals and can cause problems in the environment if it is not disposed of properly. The Environmental Protection Agency (EPA) regulates disposal of used oil from air compressors and other industrial equipment. Both the oil and oil filters must be disposed of properly to maintain compliance and avoid costly fines.

  • Used air compressor oil (including petroleum-based and synthetic oils) can be recycled or refined into a lower grade of oil or fuel. Look for a registered used oil collection center in your area. Make sure used oil is tightly sealed in spill-proof containers. Many service stations and auto parts stores are also registered oil collection centers; if you only collect a small amount of oil for recycling, you may be able to partner with one of these local businesses. Larger shops should look to their state hazardous waste program for oil recycling instructions.
  • Oil filters should be punctured and hot-drained or crushed prior to disposal. Alternatively, you may be able to turn in your used oil filters at the same facility that collects your used oil.
  • Oil collected by your oil/water separator must also be disposed of properly. Add this oil to the oil you collect during oil changes for recycling.

2. How often should I take an oil sample for my air compressor?

Oil sampling is conducted to monitor the condition of your oil and keep your air compressor in peak operating condition. It is a relatively inexpensive preventive maintenance tool. Oil sampling is typically conducted every 2,000 hours. With new equipment, you may want to sample more frequently—as often as every 500-1,000 hours—to determine the best oil change intervals for your operating patterns. Your warranty may specify oil sampling intervals, so check your user’s manual and warranty paperwork.

The oil sample is sent to a lab for analysis. An oil analysis provides data on oil viscosity, particulate concentrations and composition, pH levels and the presence of wear metals. This information is used to optimize oil change intervals for your usage patterns and environment—for example, if you are operating in a very dirty environment, the oil sample may show that you should be changing oil more frequently than the standard PM intervals in your user’s manual. Sampling can also help to diagnose emerging problems with the compressor, such as varnish buildup or excess wear of metal components. Regular oil sampling will minimize unexpected downtime and keep your air compressor operating at peak performance.

3. How can I make my air compressor quieter?

Air compressors can be quite loud. A reciprocating air compressor typically operates at noise levels of up to 85 decibels (dB), while rotary screw air compressors range from 70-75 dB. There are a number of steps you can take to turn down the volume.

  • Choose a quieter compressor. If the compressor will be operated near areas where people are working, it may be worth considering decibel levels in your buying decision. As noted above, rotary screw air compressors tend to be quieter than reciprocating compressors, but even within the same type there are differences in dB levels. When comparing units, remember that the decibel scale is logarithmic. A 3-dB increase means about double the noise, and a 10-dB difference increases perceived noise levels by a factor of 10. At 85 dB, you have to raise your voice to be heard.
  • Place the compressor in a sound-proof enclosure or a separate area with sound dampening materials such as foam board or acoustic panels. You can also hang sound blankets in the compressor room or drape them over the compressor enclosure to dampen noise.
  • Wrap the compressor. Sound blankets can be wrapped directly around the compressor itself to absorb noise from the pistons or rotors. Make sure that the material does not block the inlet, exhaust, cords or hoses.
  •  Install an intake silencer. A lot of the noise from an air compressor resonates from the air intake, which can create high-frequency pulsating noises. These muffling devices use tubes or sound-deadening materials to dampen the sound of inrushing air. They may also act as intake filters.
  • Put a rubber mat under the compressor. This will dampen vibrations between the compressor and the floor. You can also use rubber grommets on the air compressor mount.
  • Make sure your unit is in good operating condition. Inspect your unit regularly and perform all recommended PM. Tighten up any loose bolts or screws that cause the unit to rattle, monitor lubrication levels, check your bearings and belts, and change air filters regularly. A well-maintained air compressor will run quieter (and last longer).

4. Does my backup air compressor need to be the same size as my main air compressor?

Not necessarily. It depends on what you need your backup air compressor to do and how reliant your operations are on continuous compressed air. There are several ways to think about sizing your main and backup air compressors.

  • Emergency backup: In this scenario, the secondary compressor is only used if the primary compressor fails. It may be a smaller size than your main compressor. This works well if you can easily scale production or have a small number of “essential” air-using processes and other less essential applications. For example, you may have a 50HP main air compressor that can handle all your air needs at maximum production capacity. Your backup may be a 25HP compressor—not enough to ramp everyone up to full speed, but enough to avoid shutting down the entire operation while the main compressor is being repaired.
  • Auxiliary power: In this scenario, the secondary compressor is used both as an emergency backup and as an auxiliary compressor for periods of high demand. This allows you to have a smaller main compressor. The backup may be the same size or even smaller. The two compressors work in parallel when demand is at a peak. This works well for shops with highly variable demand patterns.
  • Full redundancy: In some cases, having a continuous air supply is absolutely essential. When demand is continuous and consistent, it may be worth investing in a fully redundant compressed air system. Both compressors in this scenario are sized to handle the maximum compressed air demand for the facility. When the primary unit is offline for maintenance or repair, the secondary unit takes over. You can also periodically switch between the machines to even out wear and tear.

5. Why does my compressor shut down at high temperatures?

Industrial air compressors include a temperature sensor and switch that will turn the compressor motor off if it begins to overheat. This is very important to prevent costly damage to your compressor. When ambient temperatures are high, the motor is more prone to overheating, and you are more likely to see your motor shut down unexpectedly.

You can reduce unplanned shutdowns due to air compressor overheating by keeping the compressor cooler and ensuring that there is adequate ventilation around the compressor. If your compressor is located outside, shading the area can help. If the air compressor is inside, make sure the compressor room has adequate ventilation.

Overheating can also be caused by other issues, such as plugged oil filters, loaded air filters, low oil levels or the wrong type of lubricant. Sometimes, a faulty temperature switch can also cause excessive shutdowns. If your air compressor is shutting down frequently and you have already addressed ventilation, cooling, filters and lubrication, contact a qualified repair technician to fix the problem.

6. Why do the fuses for my air compressor keep blowing?

If your air compressor keeps tripping its circuit breaker, this is a clear indication that something is wrong, either with the wiring or with the compressor itself. First, make sure that you are using an electrical source with the right voltage for your air compressor. A large air compressor should be plugged directly into an outlet with the appropriate voltage for the machine, using a heavy-duty power cord with the appropriate rating. Check your user’s manual for details.

If the wiring and electrical system check out, blown fuses may indicate a problem with the compressor that is causing it to overheat or draw too much power. Common culprits include:

  • Dirty air filter
  • Faulty motor (e.g., sparking or arcing inside the motor)
  • Faulty circuit breaker
  • Clogged pistons or issues with bearings or rotors
  • Overuse/excessive duty cycles
  • Stuck centrifugal switch
  • Shorted pressure switch
  • Failure of unloading valve

If you’re not sure what is causing your air compressor to blow fuses, you should have it checked by a qualified service technician as soon as possible.

7. Is it normal to have some residual oil in my compressed air tank?

It is not uncommon for an oil-lubricated air compressor to pass trace a

amounts of oil. This is known as “oil carryover.” Small amounts of oil may appear in your air receiver tank or be present in the compressed air supply. You can reduce oil carryover with an inline filter. A coalescing filter will remove both oil mists and dry particulate from compressed air.

However, if you notice oil pooling in the air tank or in or around the outside of your compressor, this is a problem. Oil pooled around the compressor indicates a leak somewhere in your compressor. Oil pooled in the tank may mean that the air/oil separator has failed. These are urgent problems that must be addressed before continuing to operate the machine.

8. How do I drain water from my compressed air tank?

Draining the condensate that builds up inside your compressed air system is very important. Moisture buildup inside the tank, pipes or compressor will cause corrosion over time. In the air tank, condensation will pool at the bottom of the tank, where it can be drained using a drain valve. For manual drain valves, simply open the valve and allow water to drain out into a container or floor drain until it stops running, usually only a few seconds. This should be done at least once per day and may need to be done multiple times per day.

You can reduce maintenance with an automated drain valve.

  • Electric drain valves open on a timer to drain water. They can be set to open for a few seconds at a time on a regular schedule, such as once a minute or once an hour.
  • A zero-loss drain valve uses a float mechanism to trigger the valve opening. This reduces air loss because the drain valve is only open when needed.

Drain valves may also be found on compressors, air dryers, inline filters and at low points in the compressed air piping. They should be used anywhere moisture may collect in the compressed air system.


That’s all that is in this grab bag! If you have additional questions, submit them through our contact form or call us to talk to an expert. 

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