In practice, those who have two compressors side-by-side rarely use them equally. Usually, one machine runs continuously, while the second only starts when needed – accumulating significantly fewer operating hours over the years. This is precisely where a project at an industrial company in mechanical engineering in Lombardy comes in.

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

Initial Situation

For the operation, the pure delivery volume was less of an issue than the question of how two compressors could be effectively coordinated. A single compressor covers the ongoing demand but leaves no reserve if it is serviced or fails. Two machines offer this reserve – but with a rigid assignment, they are used very unequally.

Unequal running times have practical consequences: the base load machine reaches its maintenance intervals significantly earlier, while the second machine hardly accumulates any hours. Therefore, a concept was sought that uses both compressors more evenly and makes the overall system easier to manage.

Technical solution

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

For an industrial company, two characteristics are particularly relevant: the compact design, which facilitates space-saving installation, and easy accessibility for maintenance work. Both contribute to making it practical to operate two machines side-by-side.

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 assigning one machine as the lead machine, this role changes weekly. In one week, compressor A takes the base load, in the following week, compressor B.

The effect is simple but effective: over a longer period, the operating hours of both machines equalise. This helps to distribute the wear 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 design of the system.

Result and operational benefits

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

• Operating hours are distributed more evenly across both compressors over the weeks.
• Maintenance requirements do not fall unilaterally on a single machine.
• The system has an operational reserve, the extent of which depends on the design.
• System management remains clear, as rotation occurs 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 division into base and reserve machines. This distributes wear and maintenance more predictably.
2. Reserve is not 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 design consideration.
3. Operating hours belong in cost accounting. Those who consider running times and maintenance cycles early make more economical decisions. These factors have a greater impact over the entire service life than the pure purchase price.

Frequently Asked Questions

What does parallel operation mean for compressors?

In parallel operation, several compressors work together on the same compressed air network. They can share the load and complement each other. How the machines are coordinated – for example, with a fixed lead machine or with rotation – depends on the chosen control concept.

Why is weekly rotation useful?

Weekly rotation allows the lead role to switch between machines. This means both compressors accumulate a similar number of operating hours over time, wear is distributed more evenly, and maintenance times do not fall unilaterally on a single machine.

Does a second compressor secure full production?

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

Which businesses is this concept suitable for?

This concept is interesting wherever a continuous compressed air supply is important and two or more machines are sensible anyway. The concept is interesting for businesses where continuous compressed air supply and predictable maintenance are important.

Designing Parallel Operation Correctly

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