What's the difference between backup, standby, and redundant compressors?

January 28, 2021

5 minutes

Air compressors are the power behind a business’ production; whether its food packaging, CNC machining, wastewater treatment, or any other application, they play an essential role in making sure your production continues without issue. But what if your compressor(s) unexpectedly break down? Even the most reliable machine can suddenly shutdown – so what then?

The easy answer: activate your contingency plan, which should include switching to either your backup, standby, or redundant compressor. This will make sure that your production stays up and running until you can get your primary unit repaired. Let’s learn more about each of these types of compressors actually are and how they are absolutely essential to your business.

What’s a backup compressor and why might I need one?

A backup compressor is just that – a unit that is a back-up to your existing compressor. It’s there as a safety net and is available for immediate use if your existing compressor decides to stop working. It’s better to be proactive and have a second compressor on hand for these “just in case” scenarios than to be left without a working compressor – which could bring your production to a screeching halt.

What’s a standby compressor and why might I need one?

A standby compressor is similar to a backup compressor, but unlike the latter, it doesn’t only sit around your facility as an insurance policy. Instead, a standby compressor is connected to your compressed air system and will turn on when the need arises. Keep in mind that this need isn’t only when a compressor failure happens; it also means that the standby compressor will be brought online during periods of peak demand/increased production.

What’s a redundant compressor and why might I need one?

Redundancy in air compressors is simple: two (or more) air compressors operate in parallel, alternating to meet demand – but either compressor is fully capable of handling the entire demand for compressed air on its own. This means that if one of the units shuts down, the second unit then takes on the full demand and production continues. The benefits of this are obvious: no downtime, no impact to the bottom line, and no spoiled products. It’s also beneficial when scheduling service, given that maintenance can be performed whenever is necessary – which eliminates the need to wait for after hours, weekends, or holidays.

Why a redundant air compressor is the gold standard for critical operations

Of the three contingency options discussed in this blog, a redundant air compressor system offers the highest level of protection against production disruption. While a backup compressor requires manual intervention to bring online and a standby compressor still introduces a brief switchover period, a truly redundant air compressor system is designed so that production never stops, even for a moment.

This is because in a redundant air compressor setup, both units are actively running and sharing the compressed air load at all times. There is no waiting for a second unit to start up, no pressure drop during the transition, and no risk of the standby unit failing to start when it is needed most. The system simply absorbs the full demand onto the remaining unit without any interruption to the process or the people depending on it.

Industries where even a few minutes of compressed air downtime can have serious consequences, such as food and beverage production, pharmaceutical manufacturing, semiconductor fabrication, and continuous process industries, are the strongest candidates for a redundant air compressor system. In these environments, the cost of a production stoppage, whether measured in spoiled product, missed output targets, or safety risks, far outweighs the additional investment of a second full-capacity compressor.

A redundant air compressor also provides a level of scheduling flexibility that neither a backup nor a standby compressor can match. Because either unit is capable of carrying the full load independently, maintenance and servicing can be performed on one compressor during normal production hours without any impact on operations. This eliminates the need to schedule maintenance during off-hours, weekends, or holidays, saving on service costs and making maintenance planning significantly more convenient.

How to size a redundant air compressor system

Sizing a redundant air compressor system correctly is critical to ensuring it delivers the protection it promises. The fundamental requirement is straightforward: each compressor in the redundant pair must be independently capable of meeting the full compressed air demand of your facility or process on its own.

This means that if your facility requires 500 CFM at 100 PSI to operate, each compressor in your redundant system must be rated to deliver at least 500 CFM at 100 PSI. Running two compressors that each deliver 250 CFM is not a redundant system, it is a parallel system, because neither unit can independently sustain the full load if the other fails.

When sizing your redundant air compressor system, it is also important to account for future growth in your compressed air demand. Selecting units with some additional capacity headroom ensures that your redundant system remains effective even as production scales up over time. An Atlas Copco compressed air expert can help you assess your current and projected demand and recommend the right compressor size and configuration for your specific operational requirements.

So now it’s time for you to decide: can your business afford the downtime in the case of compressor failure? In most cases, the answer is no, which makes the above options so important to implement! At least one of the three possibilities described above is sure to be an ideal fit for your facility. Reach out to our air experts at www.atlascopco.com/air-usa to discuss which one would work best for your business!

Frequently asked questions

What is a redundant air compressor?

A redundant air compressor is a compressor that operates in parallel with one or more other compressors, with each unit individually capable of meeting the full compressed air demand of the facility on its own. Unlike a backup compressor, which sits idle until needed, or a standby compressor, which activates only during peak demand or failure, a redundant air compressor runs continuously alongside the primary unit. If one compressor fails or requires maintenance, the other seamlessly absorbs the full load with zero interruption to production.

What is the difference between a backup, standby, and redundant compressor?

A backup compressor is kept available but offline, ready to be manually activated if the primary compressor fails. A standby compressor is connected to the system and will automatically come online during peak demand or in the event of a failure, but it is not running continuously under normal conditions. A redundant air compressor operates in parallel with the primary unit at all times, with each compressor capable of independently handling the full system demand. Redundancy offers the highest level of protection against downtime, while backup and standby solutions offer progressively lower levels of protection at a lower initial investment.

What industries benefit most from a redundant air compressor system?

Industries where compressed air is critical to continuous production and where downtime carries serious financial, safety, or quality consequences benefit most from a redundant air compressor system. These include food and beverage manufacturing, pharmaceutical production, semiconductor and electronics fabrication, automotive assembly, hospitals and medical facilities, and wastewater treatment plants. In any environment where stopping production, even briefly, results in significant losses or risks, a redundant air compressor system is the most reliable safeguard available.

Is a redundant air compressor system worth the investment?

For most critical production environments, yes. While a redundant air compressor system requires a higher upfront investment than a single compressor with a backup or standby unit, the cost of even a single unplanned production stoppage often exceeds the price difference many times over. Beyond protecting against downtime, a redundant system also provides scheduling flexibility for maintenance, extends the service life of each individual compressor by sharing the operational load, and gives operators greater peace of mind. When evaluated against the total cost of ownership and the potential cost of downtime, a redundant air compressor system is frequently the most cost-effective long-term choice for critical operations.

Can I convert my existing compressor system into a redundant air compressor setup?

In many cases, yes. If your existing compressor is capable of independently meeting your full compressed air demand, adding a second compressor of equal capacity and connecting both units to run in parallel is a common and practical approach to achieving redundancy. However, it is important to ensure that your compressed air system, including piping, controls, and air treatment equipment, is designed to support parallel operation and automatic load sharing between the two units. Consulting a compressed air specialist before making changes to your system will help ensure the upgrade is carried out correctly and delivers the full benefits of a redundant air compressor configuration.