Low pressure two stages screw compressor LHPM Series

The LHPM series two-stage low-pressure screw air compressors are designed for industrial processes requiring high and fluctuating air delivery at working pressures of 4.5 or 5.5 bar. The combination of two-stage compression, a permanent magnet motor and variable speed control allows compressor output to adapt to current compressed air demand.

The series includes models from 55 to 250 kW, with free air delivery ranging from 4.5 to 62 m³/min. These compressors are suitable for pneumatic conveying, textile manufacturing, food processing, cement production and other technological processes requiring continuous compressed air at relatively low pressure.

Two-Stage Low-Pressure Screw Air Compressors with Permanent Magnet Motors

The LHPM series combines a two-stage screw airend, permanent magnet motor and variable speed control. Air is compressed consecutively in two stages instead of reaching final pressure in a single compression stage.

This design is intended for industrial systems with high and continuous air demand. Dividing compression between two stages supports stable operation at working pressures of 4.5 or 5.5 bar.

Variable speed control regulates motor speed according to current demand. When load decreases, compressor output can be reduced. As consumption rises, the system increases air delivery within the operating range of the selected model.

Models from 55 to 250 kW

The LHPM series includes eight main models:

SCR530LHPM – 55 kW;
SCR830LHPM – 90 kW;
SCR950LHPM – 110 kW;
SCR1200LHPM – 132 kW;
SCR1300LHPM – 160 kW;
SCR1500LHPM – 185 kW;
SCR1900LHPM – 200 kW;
SCR2200LHPM – 250 kW.

The SCR530LHPM is suitable for installations with low to medium air consumption. The SCR830LHPM and SCR950LHPM can supply larger production lines and industrial areas.

The SCR1200LHPM, SCR1300LHPM and SCR1500LHPM are intended for large industrial systems, while the SCR1900LHPM and SCR2200LHPM cover installations with very high and continuous air demand.

Selection should not be based on motor power alone. Required air delivery, working pressure, load profile and pressure losses through the pipeline network must all be considered.

Free Air Delivery from 4.5 to 62 m³/min

The series covers an overall free air delivery range from 4.5 to 62 m³/min.

Individual model ranges are:

SCR530LHPM – 4.5–15 m³/min;
SCR830LHPM – 7.1–23.7 m³/min;
SCR950LHPM – 8.4–28.2 m³/min;
SCR1200LHPM – 10.2–34.2 m³/min;
SCR1300LHPM – 12.4–41.6 m³/min;
SCR1500LHPM – 14.0–46.9 m³/min;
SCR1900LHPM – 15.0–50.0 m³/min;
SCR2200LHPM – 18.6–62.0 m³/min.

These values represent the operating output range of each model. The exact operating point must be determined according to actual consumption and required pressure.

For a new installation, minimum, average and maximum air demand should be calculated. For an existing system, air flow measurements under different production conditions are recommended.

Working Pressure of 4.5 and 5.5 Bar

All listed LHPM models are available in versions for 4.5 and 5.5 bar. This positions the series between standard low-pressure compressors for approximately 2–4 bar and conventional industrial compressors for 7–10 bar.

This pressure range is suitable for industrial processes requiring more pressure than typical aeration and low-pressure conveying systems, without requiring the standard 7 or 8 bar used by many pneumatic machines.

The lowest pressure at which the process operates reliably should normally be selected. Pressure losses through pipelines, filters, coolers and other system components must also be considered.

Generating compressed air at a higher pressure than necessary can increase electricity consumption.

How Two-Stage Compression Works

In a two-stage design, the first stage compresses air to an intermediate pressure. The second stage then reaches the required final pressure.

This arrangement reduces the compression ratio of each individual stage and is suitable for high-power machines operating for extended periods.
Actual efficiency depends on airend design, cooling, pressure setting, operating range and the condition of the complete system.

Advantages of Variable Speed Control

The permanent magnet motor and VSD control allow compressor output to follow current compressed air demand.

The main advantages include:

smooth air delivery regulation;
adjustment to fluctuating demand;
more stable system pressure;
reduced unloaded operation;
fewer sudden load changes;
smoother motor starting;
improved balance between produced and consumed air.

Benefits depend on correct sizing. An oversized compressor or incorrect pressure setting can cause operation outside the optimum range.

A Two-Stage Low-Pressure Compressor Instead of a Standard 7–10 Bar Unit
When a production process requires 4.5 or 5.5 bar, using a standard compressor designed for 8 or 10 bar and reducing pressure afterwards may create unnecessary energy losses.

LHPM compressors generate air directly within the required pressure range. This is particularly important at high air delivery and during continuous operation, where even a small pressure difference can significantly affect total energy consumption.

Selection must consider pressure at the final point of use and actual losses through the air network.

Applications of LHPM Compressors

Pneumatic Conveying

High air delivery and working pressure up to 5.5 bar are suitable for conveying powdered and granular materials through pipeline systems.

Textile Manufacturing

Textile facilities can use compressed air for process equipment, material movement, cleaning and continuous manufacturing operations.

Food Processing

The compressors can supply packaging, conveying and other technological processes. Where compressed air comes into direct or indirect contact with products, suitable treatment and the required air quality must be provided.

Cement and Construction Material Production

Compressed air can be used for pneumatic conveying, aeration, homogenisation and other continuous processes.

Large Industrial Systems

Models delivering up to 62 m³/min are suitable for central installations and facilities with high multi-shift consumption.

DN80 to DN200 Outlet Connections

Connection sizes increase according to compressor output:

SCR530LHPM – DN80;
SCR830LHPM and SCR950LHPM – DN100;
SCR1200LHPM and SCR1300LHPM – DN125;
SCR1500LHPM and SCR1900LHPM – DN150;
SCR2200LHPM – DN200.

Correct pipeline sizing is critical at high air delivery. An insufficient diameter increases air velocity and pressure losses.

Pipeline length, bends, branches, valves, filters and maximum simultaneous consumption must be considered during design.

How to Select the Correct LHPM Compressor

Determine Required Air Delivery
Calculate the total consumption of all equipment that may operate simultaneously. Minimum load and short-term peaks should be considered in addition to average demand.

Select Between 4.5 and 5.5 Bar
Use the lowest pressure that ensures reliable operation at the final point of use. Add only the reserve required for actual system losses.

Analyse the Load Profile
When demand changes considerably, variable speed control allows output to adapt. If the process operates almost continuously at maximum load, different compressor station arrangements should be compared.

Allow for Future Expansion
A reasonable reserve supports additional equipment. Excessive oversizing, however, can reduce efficiency during low-load operation.

Check Installation Conditions
The models weigh between 2,700 and 6,500 kg and reach dimensions of 3580 × 2200 × 2300 mm. A suitable foundation, reliable ventilation, service space and a planned delivery route are required.

Designing a High-Flow Compressed Air System
For compressors delivering up to 62 m³/min, machine selection should form part of a complete system design.

The installation may include:

air receivers;
coolers;
air dryers;
line filters;
condensate drainage systems;
main and distribution pipework;
automatic multiple-compressor control;
air flow and energy monitoring.

All components must be sized according to maximum air delivery, working pressure and required compressed air quality.

Consultation for LHPM Compressor Selection
Correct selection requires information about average and maximum demand, required pressure at the point of use, operating hours and pipeline characteristics.

Contact our team for technical consultation and assistance in selecting an LHPM series two-stage low-pressure screw air compressor according to the requirements of your industrial process.