How Much Noise Do Screw Compressors Generate?

In general, screw air compressors are recognized for their relatively low noise levels compared to other compressor types, particularly reciprocating (or piston) compressors. Piston compressors are notorious for generating high noise and vibration, which can be felt throughout the workspace. Consequently, they are often placed in separate rooms, closets, or outdoors, which can affect their performance and longevity.

The noise produced by screw compressors can vary based on several factors, including the compressor's size and type, the surrounding environment, and, to some extent, the operating speed. Depending on the specific model and operating conditions, noise levels can range from just over 60 dB(A) to more than 90 dB(A). For context, the average vacuum cleaner operates at around 75 dB(A), while piston compressors typically range from 80 to 90 dB(A).

Screw compressors operate more quietly than reciprocating compressors due to their rotary motion. This design significantly reduces vibration, as the rotary mechanism minimizes movement. Additionally, screw compressors often feature insulated cabinets, further contributing to their lower noise levels. In contrast, piston compressors are typically bolted to the floor to maintain stability, which can amplify vibrations and noise. The sound level on screw compressors is low enough to have a normal conversation near the machine (a convenience and a plus for safety). Being relatively quiet and vibration free, they offer more flexibility where you put them, such as a spot with better lighting, service access and ventilation. Ventilation is critical to the longevity of any compressor.

Although screw compressors are generally quiet, they can appear louder in small rooms or spaces with low ceilings. Concrete floors and walls tend to reflect noise, amplifying sound levels. To mitigate this, consider applying sound-absorbing materials to the walls of the compressor room, which can make a noticeable difference. For screw compressors housed in cabinets, ducting the exhaust air outside can significantly reduce noise. In contrast, enclosing piston compressors is often impractical due to heat buildup and insufficient airflow for cooling.

If you notice a change in noise levels from a screw compressor, it may indicate a service issue, such as inadequate lubrication. The same principle applies to piston compressors.

Ten Tips to Make Your Air Compressor Quieter

Choose a Quieter Compressor Model  

Noise levels can vary significantly between different air compressor models. Typical rotary screw air compressors operate within a range of 70-75 dB, which is comparable to standing next to a busy highway. In contrast, reciprocating air compressors can generate noise levels of up to 85 dB, making it necessary to raise your voice to be heard and causing considerable nuisance. Therefore, selecting a quieter model is the first step to lowering the volume in the compressor room. However, if that’s not feasible due to your air needs or if it's already too late, there are still numerous ways to quiet your existing compressor.

Move a Noisy Air Compressor Away from Workspaces  

Placement is crucial for managing noise levels. Positioning your compressor in a dedicated room or a remote corner, away from active work areas, can significantly reduce noise disturbance. Alternatively, consider placing your compressor outside, ensuring it is properly weatherized for your local climate conditions. The greater the distance between the compressor and work areas, the less intrusive the noise will be. Keep in mind that longer duct runs may affect performance when making placement decisions.

Create an Acoustic Barrier Between the Air Compressor and Workspaces  

Enclosing your compressor in a closed room or behind a sound-dampening wall can help prevent noise from traveling. Heavy materials like concrete blocks provide better sound insulation than thin wooden walls. For smaller compressors, you might consider building a custom enclosure to muffle noise rather than dedicating a room. Just ensure there is ample air space around the compressor and adequate ventilation to prevent overheating; consult your user manual or manufacturer for specific ventilation requirements for your model.

Insulate the Compressor Room with Sound-Dampening Materials

For even more noise reduction benefits, insulate your compressor room or enclosure with sound-dampening materials. Sound blankets are an easy fix: simply drape them over the compressor enclosure or hang them on the walls in the compressor room. Foamboard or acoustic panels can also be added to the compressor room walls. Be sure to allow for adequate airflow around the compressor. Use fire-resistant materials and make sure they are not in contact with the compressor or other heat-producing machinery.

Wrap the Compressor in Sound-Dampening Materials  

If your compressor is not located in an enclosed area, consider wrapping it with sound blankets. These blankets can significantly absorb noise generated by the compressor's pistons or rotors. Ensure that the sound-dampening material is fire-retardant and does not obstruct the inlet, exhaust, cords, or hoses.

Install an Intake Silencer  

Much of the noise from an air compressor originates from the air intake, which can produce high-frequency pulsating sounds. An intake silencer is a device designed to muffle this noise by using tubes or sound-deadening materials to dampen the sound of incoming air. Additionally, intake silencers may also function as filters for the air intake.

Place the Compressor on a Rubber Mat to Absorb Vibrations  

Vibrations are another significant contributor to air compressor noise. The movement of the pistons or rotors can transfer vibrations through the floor, amplifying the noise throughout the facility. Placing a rubber mat under the compressor can help absorb these vibrations and prevent them from transferring through the floor. Cork or plastic materials also offer good shock-absorbing properties. Alternatively, you can use rubber grommets or feet on the compressor mount instead of a full rubber mat. These grommets work similarly to the mat, absorbing vibrations and minimizing noise transfer.

Check Lubrication Levels for the Air End and Bearings  

You’re checking lubrication levels regularly, right? Proper lubrication is essential for a quieter air compressor. For oil-flooded compressors—whether rotary screw, rotary vane, or piston-style—it’s important to monitor the oil level several times a week to ensure it doesn't run low. Change the oil at least once a year, or more frequently depending on your operating hours and conditions. Additionally, remember to grease the bearings in your air compressor motor. A well-lubricated compressor not only operates more quietly but also has a longer lifespan.

Change Your Air Filters  

Clogged intake and inline air filters force your air compressor to work harder, resulting in increased noise levels. Replace intake filters when they appear visibly dirty or worn. Inline filters should be changed at least once a year or after approximately 8,000 operating hours. Monitoring pressure drop—measuring the difference in pressure before and after the filter—can help you determine when filters need replacement.

Tighten Up Anything that Rattles, Shakes, or Shimmies  

Regular maintenance is crucial. As your air compressor operates, vibrations can cause components to loosen over time. Tighten any loose bolts or screws that may be causing the unit to rattle, and check your bearings and belts to ensure they are in good condition. Reducing excessive rattling not only lowers noise levels but also helps prevent costly repairs in the future.