Rotary screw compressors are commonly used where a workshop or industrial site needs a repeatable compressed-air supply across longer operating periods than a small intermittent compressor is designed to provide. The machine is only one part of the final system, so airflow, pressure, storage, treatment, distribution and electrical supply should be considered together.
How rotary screw compression works
A rotary screw compressor uses meshing rotors to compress air continuously as they rotate. In an oil-injected machine, oil assists sealing, cooling and lubrication before being separated from the compressed air within the package.
The final air quality still depends on the separator, dryer, filters, drains and distribution system. A rotary screw compressor should not be described as delivering process-quality air without the appropriate treatment specification.
FAD is the useful airflow figure
Free air delivery, or FAD, is intended to describe the delivered airflow referenced back to inlet conditions. It is more useful for comparing compressor capacity than displacement or motor power alone.
- PM10 - 1,000 L/min at 8 bar
- PM20 - 2,100 L/min at 8 bar
- PM30 - 3,200 L/min at 8 bar
Maximum pressure is stated separately as up to 10 bar / 145 PSI where applicable. Do not describe PM30 FAD as measured at 10 bar.
The three Pneumatix output levels
The Pneumatix compressor range is built around three output levels. Every model is a variable-speed rotary screw machine rated to a maximum working pressure of 10 bar, with free air delivery quoted at 8 bar so the three figures compare directly.
| PM10 | PM20 | PM30 | |
|---|---|---|---|
| Free air delivery at 8 bar | 1,000 L/min | 2,100 L/min | 3,200 L/min |
| Maximum working pressure | 10 bar / 145 PSI | 10 bar / 145 PSI | 10 bar / 145 PSI |
| Motor | 7.5 kW / 10 HP | 15 kW / 20 HP | 22 kW / 30 HP |
| Three-phase circuit breaker | 20 A D-curve | 32 A D-curve | 50 A D-curve |
| Configurations | Base Mount, Total Air Station | Base Mount, Total Air Station | Base Mount |
Circuit breaker sizes are the Pneumatix recommendation for the three-phase compressor supply. Final circuit design, cable sizing and protection remain the responsibility of the licensed electrician for the installation.
Horsepower does not define the whole system
Motor power can help describe the size class, but it does not tell you the delivered airflow, control method, receiver arrangement, dryer capacity, filtration or pressure loss. Compare the full system and the verified FAD figure.
Total Air Station versus Base Mount
Total Air Station
A Total Air Station combines the compressor with an air receiver, refrigerated dryer and inline filtration in a receiver-mounted package. Pneumatix offers PM10 and PM20 Total Air Stations.
Base Mount
A Base Mount provides the compressor only. It suits systems where the receiver and treatment are selected separately. Pneumatix offers PM10, PM20 and PM30 Base Mounts.
Variable-speed control
Every compressor in the Pneumatix range is variable speed. Where a fixed-speed machine meets a lower demand by unloading and blowing off, a variable-speed drive holds pressure by matching motor speed to what the site is actually drawing, which reduces the number of unloaded running hours and keeps supply pressure steadier through changes in demand. The benefit is largest where demand varies through the day and smallest where the site draws close to full output continuously.
A variable-speed drive does not remove the need for storage, and it does not change the air-treatment requirement. Read more about variable-speed compressors.
Receiver storage
In the Pneumatix range, storage is what separates the two configurations. A Total Air Station arrives with the receiver already fitted and plumbed: 300 litres on the PM10 Total Air Station and 500 litres on the PM20 Total Air Station. A Base Mount is the compressor alone, so the receiver, its mounting and the pipework between them are specified separately for the site.
Storage volume is sized against the size and frequency of demand peaks rather than against the compressor alone. A short, heavy draw such as a tyre changer or a blast nozzle is met from stored air; a continuous draw is met by the compressor. Undersized storage shows up as pressure dropping away during peaks and as the machine cycling more often than the duty warrants.
Drying and filtration
Compression concentrates moisture and contamination. Dryer and filter selection should be matched to the airflow, pressure and ambient conditions at the installation, and to what the downstream equipment and process actually require.
Two refrigerated dryers are offered: the PMD1200 at 1,200 L/min and the PMD2400 at 2,400 L/min, both with a 2 to 10 °C dew point range. PMF inline filters are used in pairs around the dryer, a 1.0 micron pre-filter ahead of it and a 0.01 micron post-filter after it. A PM10 or PM20 Total Air Station arrives with a tank-mounted dryer and both filter grades already included; a Base Mount does not, so treatment is specified with the rest of the system.
Duty and operating environment
Consider operating hours, ambient temperature, dust, ventilation, service access and the consequences of an unplanned stop. These decide how hard the machine works and how easily it can be maintained.
A rotary screw compressor rejects heat continuously while it runs, so the room has to move that heat away. A machine in a small, closed or dusty space runs hotter than the same machine in a ventilated one, and heat is the condition that shortens the life of the drive, the separator and the lubricant. Allow the ventilation and clearance set out in the current manual, keep the intake away from paint, solvent and exhaust fumes, and leave room to open the panels for service rather than working around the machine after it is installed.
Where an unplanned stop halts the whole workshop, the duty question is not only which machine meets the demand but how the site keeps working while one is being serviced. Plan the complete compressed-air system covers the distribution and layout decisions that sit around the compressor.
Electrical supply and installation
Every model in the Pneumatix compressor range is a three-phase machine. Pneumatix recommends a D-curve circuit breaker sized to the model: 20 A for the PM10, 32 A for the PM20 and 50 A for the PM30. A D-curve device is specified because the drive draws a brief inrush on start that a lower-curve breaker can read as a fault.
Cable size, run length, installation method, protection and isolation are determined by the licensed electrician against AS/NZS 3000 for the specific installation, not from a published table. The Pneumatix Best Practice Electrical Installation Guides set out the recommended arrangement for each model and should be provided to the electrician before the machine is connected.
How to choose PM10, PM20 or PM30
- List air-consuming equipment.
- Confirm required pressure.
- Estimate realistic duty cycle.
- Identify simultaneous use.
- Allow deliberately for leaks and growth.
- Select receiver storage.
- Select treatment.
- Confirm electrical capacity and location.
- Compare the resulting requirement with verified FAD.
Frequently asked questions
Is a rotary screw compressor suitable for occasional light use?
It may not always be the most appropriate choice. Operating pattern, required airflow and total system needs should be reviewed.
Is maximum pressure the same as airflow rating pressure?
No. Pneumatix publishes FAD at 8 bar and states maximum pressure separately.
Does a VSD compressor need a receiver?
Receiver requirements depend on the system and control behavior. Variable speed does not automatically remove the need for storage.
Which Pneumatix product is the largest?
The PM30 Base Mount is the highest-output current model at 3,200 L/min at 8 bar.
What size circuit breaker does each model need?
Pneumatix recommends a 20 A D-curve breaker for the PM10, 32 A for the PM20 and 50 A for the PM30, on a three-phase supply. Cable sizing and final circuit design are determined by the licensed electrician for the installation.
Does a Base Mount include a receiver, dryer or filters?
No. A Base Mount is the compressor on its own. The receiver, refrigerated dryer and inline filters are specified separately for the site. A PM10 or PM20 Total Air Station includes the receiver, a tank-mounted dryer and both filter grades as a coordinated package.
Why is airflow quoted at 8 bar when the machine is rated to 10 bar?
Free air delivery is a flow figure and only means something against the pressure it was referenced to. Pneumatix quotes flow at 8 bar for every model so the three compare directly, and states the 10 bar maximum working pressure separately as a capability. The flow figure is not a measurement taken at 10 bar.
Use the range as a starting point, then confirm the application
Compare the five configurations and provide the site equipment, simultaneous demand, pressure, storage and treatment requirements to Pneumatix or your dealer.
Related Pneumatix guidance
- How to size an air compressor — working from equipment list to required airflow.
- How to choose a workshop air compressor — selection by workshop type.
- VSD air compressors — how variable-speed control behaves against demand.
- Plan the complete compressed-air system — storage, distribution and layout.
- Air treatment — drying and filtration for the whole system.
- Warranty, parts and service — ongoing support and consumables.