Side Channel Blower Frequency Range

Operating frequency of a side channel blower has a direct influence on airflow, pressure, motor speed, temperature, and overall system performance.

When a side channel blower is controlled by a Variable Frequency Drive (VFD), its operating speed can be adjusted according to actual airflow and pressure requirements.

For many side channel blower applications, 28–60 Hz is the recommended operating frequency range, while some specially configured models can operate at frequencies of up to approximately 78 Hz.

However, higher frequency does not always mean better performance. The blower must remain within its permitted operating limits.

What Is the Recommended Frequency Range for a Side Channel Blower?

For most applications, the recommended VFD-controlled operating range is:

28–60 Hz

This range offers a practical balance between:

• Airflow control
• Pressure or vacuum performance
• Motor cooling
• Noise level
• Bearing life
• Operating temperature
• Energy consumption

At 50 Hz or 60 Hz, the blower normally operates close to its standard rated condition, depending on the motor and electrical configuration.

Reducing the frequency allows the blower to run at a lower speed when the system does not require full airflow.

Why Is 28–60 Hz the Best Operating Range?

Better Airflow Control

Changing the frequency changes the rotational speed of the motor and impeller.

When frequency increases, blower speed generally increases, producing more airflow and potentially higher pressure.

When frequency decreases, blower speed decreases, reducing airflow and energy consumption.

This makes VFD control useful in applications where air demand changes during operation, such as:

• Wastewater aeration
• Aquaculture aeration
• Vacuum systems
• Pneumatic conveying
• Air knife drying
• Packaging equipment
• Industrial automation

Instead of continuously operating the blower at maximum output, the VFD can adjust the blower according to actual system demand.

More Efficient Operation

Operating between 28 and 60 Hz helps keep the blower within a practical speed range.

For example, if a production process requires less airflow during certain periods, reducing the blower frequency can lower unnecessary power consumption.

This is especially useful in systems where airflow demand is not constant.

However, frequency should not be reduced excessively. At very low motor speeds, the cooling effect generated by the motor fan may decrease, which can increase motor temperature.

Therefore, continuous operation below the recommended minimum frequency should be carefully evaluated.

Can a Side Channel Blower Run Above 60 Hz?

Yes. Certain side channel blower configurations can operate above 60 Hz when used with a suitable VFD and motor.

For some DEREIKE blower configurations, the maximum frequency can reach approximately 78 Hz.

However, 78 Hz should be considered a maximum operating limit for suitable configurations, rather than the preferred continuous operating frequency for every blower.

Before increasing frequency above 60 Hz, several factors should be checked.

Motor Speed

Higher frequency increases motor rotational speed.

If the motor and impeller are not designed for the increased speed, excessive mechanical stress may occur.

Motor Current

Higher speed can increase the load on the motor.

The operating current should always remain within the motor’s permitted limits.

Blower Temperature

A side channel blower compresses and circulates air internally, which naturally generates heat.

Increasing speed can increase:

• Air temperature
• Motor temperature
• Bearing temperature
• Internal blower temperature

Temperature must therefore be monitored when operating at high frequency.

Pressure and Vacuum

Higher frequency can increase blower performance, but the blower must still operate within its allowable pressure or vacuum range.

Running at excessive differential pressure can lead to overheating even when the frequency itself is within the permitted range.

Does Higher Frequency Always Mean Higher Performance?

Not necessarily.

Increasing frequency usually increases rotational speed and airflow, but actual performance depends on the complete system resistance.

A blower should therefore not be selected only according to maximum frequency.

The correct selection process should consider:

Required Airflow → Required Pressure/Vacuum → Performance Curve → Operating Frequency

For example, if a system already reaches its required airflow at 50 Hz, increasing the blower to 70 Hz may provide little practical benefit while increasing noise, temperature, and mechanical load.

The goal should be to find the most efficient operating point rather than simply running the blower as fast as possible.

Important Points When Using a VFD

When controlling a side channel blower with a VFD, keep these points in mind:

• Use 28–60 Hz as the preferred operating range when applicable.
• Frequencies up to approximately 78 Hz should only be used on suitable blower and motor configurations.
• Do not exceed the motor’s rated current.
• Monitor blower and motor temperature.
• Avoid operating beyond the permitted pressure or vacuum limit.
• Check the blower performance curve at the actual operating frequency.
• Make sure sufficient airflow remains available for blower cooling.
• Confirm voltage and VFD settings before operation.

Frequency, Airflow, and Pressure Must Be Considered Together

One common mistake is selecting a blower based only on its rated airflow.

The actual airflow changes according to both frequency and system pressure.

For example, a blower may have a relatively high free-air flow rate, but once it operates against pipe resistance, diffuser depth, filters, valves, or other restrictions, the actual airflow will decrease.

Therefore, blower selection should always be based on the required operating point rather than maximum specifications alone.

For aeration systems, the basic selection logic can be expressed as:

Water Depth → Required Pressure → Required Airflow → Blower Performance Curve → Frequency Adjustment

The same principle applies to vacuum, conveying, drying, and other industrial applications.

Conclusion

For most VFD-controlled side channel blower applications, 28–60 Hz provides the most practical operating range for balancing airflow, pressure, efficiency, temperature, and reliability.

Some specially configured blowers may operate at frequencies of up to approximately 78 Hz, but high-frequency operation should always be verified according to the motor, blower model, operating pressure, current, and temperature.

The best frequency is not necessarily the highest frequency.

It is the frequency that allows the blower to deliver the required airflow and pressure while remaining within a stable and safe operating range.