In practice, anyone with two compressors standing side by side rarely uses them equally. Usually one machine runs continuously, while the second only starts when needed—and over the years accumulates significantly fewer operating hours. This is exactly where a project at an industrial company in mechanical manufacturing in Lombardy comes in.

Instead of operating a fixed base-load machine and a standby machine, two STORM-series screw compressors were connected in parallel and programmed to swap the lead role weekly. The goal: to distribute run times more evenly and create a predictable operating reserve.

Initial Situation

For the operation, the issue was less the pure delivery volume than the question of how to make two compressors work together sensibly. A single compressor can cover ongoing demand, but leaves no reserve when it is being serviced or fails. Two machines provide this reserve—yet with a rigid assignment they are loaded very unevenly.

Unequal run times have practical consequences: the base-load machine reaches its service intervals much sooner, while the second machine barely accumulates hours. The aim was therefore a concept that uses both compressors more evenly and makes the overall system easier to manage.

Technical solution

The SCC STORM series was used. These are oil-injected screw compressors with direct drive and a variable-speed IE4 permanent-magnet motor. The speed control continuously adapts the air output to actual demand. The series covers a power range from 5.5 to 75 kW; which model size was installed in the project is not stated in the project details.

For an industrial company, two characteristics are particularly relevant: the compact design, which makes space-saving installation easier, and easy access for maintenance work. Both help make operating two machines side by side practical.

System concept: parallel operation with weekly rotation

The two compressors were connected in parallel and operate on the same compressed-air network. Instead of permanently defining one machine as the lead unit, this role changes on a weekly cycle. One week, compressor A takes the base load; the following week, compressor B.

The effect is simple but effective: over a longer period, the operating hours of both machines converge. This helps distribute the load and the resulting maintenance requirements more evenly across both machines.

Whether a single machine can cover the full demand in the event of a fault depends on the sizing and the current air demand. Parallel operation creates a reserve; its extent results from the specific system design.

Result and operational benefits

The project goal was not a record efficiency value, but a more balanced system that is easier to manage. The chosen concept results in the following points:

• Operating hours are distributed more evenly across both compressors over the weeks.
• Maintenance requirements do not fall one-sidedly on a single machine.
• The system has an operating reserve, the extent of which depends on the system design.
• System management remains clear, as the rotation takes place automatically on a weekly cycle.

Three lessons for parallel operation

1. Rotation beats rigid assignment. Two compressors connected in parallel with weekly rotation use both machines more evenly than a fixed split into a base-load and a standby machine. This distributes wear and makes maintenance more predictable.
2. Reserve is not the same as full supply. A second machine creates leeway, but does not replace a capacity check. Whether one machine alone is sufficient can only be clarified through a specific demand and system-design assessment.
3. Operating hours belong in cost accounting. Those who consider run times and maintenance cycles early make the more economical decision. These factors have a stronger impact over the entire service life than the pure purchase price.

Frequently Asked Questions

What does parallel operation mean for compressors?

In parallel operation, multiple compressors work together on the same compressed-air network. They can share the load and complement each other. How the machines are coordinated—such as with a fixed lead unit or with rotation—depends on the chosen control concept.

Why is weekly rotation useful?

Weekly rotation allows the lead role to switch between the machines. As a result, both compressors accumulate a similar number of operating hours over time, wear is distributed more evenly, and maintenance dates do not fall one-sidedly on a single machine.

Does a second compressor ensure full production?

A second compressor creates an operating reserve. Whether a single machine can cover the entire demand on its own in the event of a fault depends on the sizing and the current air demand. This can be assessed through a specific capacity review.

Which operations is this concept suitable for?

The concept is of interest wherever a continuous compressed-air supply is important and two or more machines are sensible anyway. The concept is of interest for operations where a continuous compressed-air supply and predictable maintenance are important.

Sizing parallel operation correctly

Are you planning a similar solution with two or more compressors? Please share operating pressure, air demand, operating times, and the key requirements of your application. On this basis, it can be clarified whether rotation makes sense and what reserve the system design provides. SCC and the regional partner network support you with technical classification and advice; a structured demand calculation is a good first step.