Atlas Copco GA 55 (55⁺ Pack FF) Oil-Injected Rotary Screw Air Compressor

Description

The Atlas Copco GA 55 is the 55 kW member of the GA 30+-90 oil-injected screw family and the entry point to the large frame that the platform shares with the GA 75 and GA 90. It is built for plants that plan their compressed air around a fixed operating pressure and want a GA 55 that holds its setpoint year after year.

The model comes in two branches: the GA 55 with free air delivery up to 179 l/s and the GA 55+ with up to 191 l/s at the same motor rating, and every version ships as a complete Pack with the element, motor, cooling system and controls arranged inside one canopy. The Full Feature branch adds the refrigerant dryer and filtration to the same frame.

Fixed speed does not mean outdated. For plants with a steady base load, the GA 55 runs at full load for most of the shift, which is the operating point where the GA 55 converts electricity into air most efficiently. The Elektronikon controller manages loading, unloading and shutdown automatically around that base load.

Where the GA 55 Fits in the Oil-Injected Range

The GA 55 opens the large-machine section of the GA 30+-90 platform: from this model upward, every machine shares the 1680 mm Pack frame, the premium motor concept and the same service concept. Plants choose it when the flow demand sits just above the GA 45 class or when a 13 bar high-pressure network needs a dedicated machine.

The four pressure versions make the GA 55 a planning tool: one model covers the whole ladder from low-pressure workshop air to high-pressure process air. The higher-output GA 55+ branch runs the same ladder one step higher in flow, so plants that expect growth can stay inside the same model choice and the same installation envelope.

What Pack and FF Mean

The Pack designation covers the complete compressor: element, IE4 motor, oil system, cooling circuit, controller and protective canopy, ready for connection to an external air treatment chain. The FF, or Full Feature, branch integrates the refrigerant dryer and filtration inside the package, so the delivered air leaves the machine already dried to a pressure dew point of 2 to 3 degrees Celsius.

Both branches use the same carrying frame, which keeps the installation planning identical apart from the added depth of the treatment chain.

Technical Specifications of the GA 55

The table below condenses the GA 55 into its headline figures:

50 Hz Pressure Versions

Unit performance of the 50 Hz versions is measured according to ISO 1217, Annex C, Edition 4:2009, with the FAD referenced to the effective working pressures of 7, 8, 9.5 and 12.5 bar(e), with the first four rows covering the GA 55 and the last four the GA 55+ branch:

60 Hz Pressure Versions

The 60 Hz versions follow the same design with pressures quoted in psig, and their performance is measured according to ISO 1217, annex E. The footnotes, reference conditions and FAD details of the 50 Hz versions apply:

The noise level of 71 dB(A) is the A-weighted emission sound pressure level at the work station, determined according to the noise level test code ISO 2151 and the noise measurement standard ISO 9614, with an uncertainty of 3 dB. The reference conditions are an absolute inlet pressure of 1 bar and an intake air temperature of 20 degrees Celsius, and the integrated refrigerant dryer holds a pressure dew point of 2 to 3 degrees Celsius at these conditions. The plus branch posts 69 dB(A) under the same test conditions.

Dimensions and Weight

The Pack measures 1680 mm deep, 1221 mm wide and 1980 mm high, and weighs 1360 kg. The Full Feature branch extends the depth to 2525 mm to house the integrated dryer and filters, keeping width and height unchanged, and weighs 1685 kg. The plus branch weighs 1365 kg as Pack and 1690 kg as Full Feature, with the same envelope. For a 55 kW machine with an integrated treatment chain, the footprint stays within the envelope of a single machine bay, and the canopy opens for service access without extra clearance at the sides.

The Premium Drive Train

IE4 Motor and Direct Drive

The GA 55 carries an IE4 efficiency motor, the highest standard efficiency class for this platform, with IP55 protection and insulation class F and a temperature rise class B that keeps the windings well inside their limits. The motor drives the element directly, with no coupling or slippage losses between the two, so the shaft power reaches the compression element unchanged.

The non-drive side bearing is greased for life, which removes it from the maintenance schedule entirely, and the whole drive system is totally enclosed and protected against dirt and dust. The machine runs in ambient conditions up to 46 degrees Celsius as standard, with a high ambient version rated for 55 degrees.

Hybrid Bearings and Filtration

New state-of-the-art hybrid bearings extend the lifetime of the drive train by 33 percent on the GA 55 to GA 90 models, and the GA 55 benefits from this design directly. The oil system runs through a robust spin-on oil filter that removes particles 300 percent smaller than a conventional filter, with an integrated bypass valve and a pressure drop indicator that shows the condition at a glance. The intake side uses a heavy-duty air filter that removes 99.9 percent of dirt particles down to 3 microns.

On the plus branch, the spin-on oil filter carries an 8,000-hour service interval and the heavy-duty intake filter an 8,000-hour lifetime.

Smart Features on the Plus Branch

Smart Temperature Control

The 55⁺ adds the Smart Temperature Control System, an intelligent algorithm that calculates the ideal oil-injection temperature from parameters such as ambient and oil temperature, pressure, load and air humidity. When necessary, the STC valve routes the oil through the coolers to reach that ideal temperature, which raises compressor efficiency and removes the risk of condensation in the oil circuit. A smart unload algorithm monitors pressure fluctuations in real time and reduces the running time in unload, so even a fixed speed machine wastes as little energy as possible between load phases.

Intelligent Sensors and EQ2i Control

Pressure drop sensors monitor the lifetime of the inlet filter, the oil separator and the oil filter, so each consumable is replaced on its actual condition instead of a fixed calendar. The GA 55+ also carries the EQ2i multiple compressor control as standard, which allows the machine to control a second compressor in the same network — a direct path to a narrow pressure band for plants that expect to grow. The smart no-loss water drain on the plus branch removes condensate automatically, cleans itself and detects potential issues before they become faults.

Full Feature: Dryer and Filters Inside the Package

The Full Feature branch turns the GA 55 into a complete air quality station. The refrigerant dryer is sized for the compressor and holds the pressure dew point between 2 and 3 degrees Celsius under all circumstances, preventing freezing at low load. An oversized dryer option is available for the 55 to 90 models when the toughest ambient conditions demand it.

Downstream, the filtration stage polishes the air to the quality class the application needs, and the no-loss condensate drain removes water without wasting compressed air. Controlled and monitored by the Elektronikon, the dryer reports its status on the same panel that runs the compressor.

Dew Point and Condensate

Condensate from the dryer and the oil separator contains oil traces and must be handled correctly. The electronic no-loss drain discharges it to the condensate management point without releasing air, and the controller supervises the drain so a fault is flagged on the panel instead of going unnoticed. Plants that feed the condensate to an oil-water separator get a clean, compliant discharge path.

Control and Connectivity

The control principle of the fixed speed platform is built around the load band. The GA 55 loads when the header pressure approaches the lower limit and unloads when it reaches the setpoint, and the Elektronikon keeps the number of these transitions low through intelligent band planning. Between load phases the machine idles rather than stops, which keeps the oil separation stable and avoids the wear that frequent restarts would bring to the motor and the element.

Elektronikon Touch

The Elektronikon Touch controller is the operating center of the GA 55. It manages the motor, guards the pressure band, schedules the service intervals and logs the operating data. The graphic display gives the operators a direct view of the status, and the built-in planning functions protect the machine against unnecessary starts and stops.

SMARTLINK and OPC UA

SMARTLINK remote monitoring is standard and reports the operational parameters of the GA 55 in real time, which lets the service organization plan interventions on data instead of guesswork. OPC UA connectivity integrates the compressor into the production monitoring system as the first compressor manufacturer to offer this protocol in this class, so the machine appears on the factory dashboard alongside the rest of the line.

Applications of the GA 55

The GA 55 covers the classic industrial load spectrum: automotive component plants, metal fabrication with plasma and laser cutting, food and beverage packaging, textile mills and general machinery shops. The 13 bar version serves high-pressure users such as PET blowing preforms, die cutting and laboratory networks, while the 7.5 bar version maximizes the flow for plants that run a single standard header. Workshops that outgrow a GA 30-45 machine use the GA 55 as the step up that keeps the same operating logic, and plants with a second compressor on site gain an additional control layer through the EQ2i of the plus branch.

Service and Support Around the GA 55

The service points of the GA 55 are grouped for access, and the spin-on filters make the routine services a short planned stop instead of a project. Atlas Copco fluids and lubricants are tailored to the 55 with anti-oxidation additives that hold their protective qualities across the service interval, and the Elektronikon tracks the remaining lifetime of every consumable.

Loading the GA 55 steadily, pairing it with adequate receiver volume and keeping the intake air clean are the three habits that decide the lifetime of the machine. For a replacement element on the oil-injected platform, see the OIS O-06 Oil-Injected Screw Element. The installed base of the GA 55 and its Full Feature branches runs across continents, and Seadweer supports the machine with original spare parts, service kits and technical documentation for every pressure version.

FAQ

Which pressure versions does the GA 55 offer?

At 50 Hz the GA 55 is available in 7.5, 8.5, 10 and 13 bar(e) versions, and at 60 Hz in 100, 125, 150 and 175 psig versions. Each version delivers between 136 and 182 l/s depending on the setting.

How much air does the GA 55 deliver?

The 7.5 bar version delivers 179 l/s (378 cfm), and the 13 bar version delivers 136 l/s (287 cfm). The 60 Hz versions reach up to 182 l/s at 100 psig. The plus branch delivers up to 191 l/s (405 cfm) at 7.5 bar.

What is the difference between the GA 55 and the GA 55+?

Both branches share the same frame, motor rating and pressure ladder. The GA 55+ adds the Smart Temperature Control System, the smart no-loss water drain, intelligent sensors on the three main filters, an 8,000-hour service interval on the oil filter and intake filter, and the EQ2i control that manages a second compressor.

What is the difference between Pack and FF?

Pack is the complete compressor without integrated air treatment, while FF, the Full Feature branch, integrates the refrigerant dryer and filtration inside the same canopy. The FF branch is 845 mm deeper and 325 kg heavier than the Pack.

How loud is the GA 55?

The sound pressure level at the work station is 71 dB(A) for the GA 55 and 69 dB(A) for the GA 55+, determined according to ISO 2151 and ISO 9614 with an uncertainty of 3 dB.

What motor efficiency does the GA 55 have?

The machine carries an IE4 efficiency motor with IP55 protection, insulation class F and temperature rise class B, driving the element directly without coupling or slippage losses.