How to choose a scroll compressor: oil-free air

If you need oil-free compressed air and the room cannot be noisy, the answer is the scroll compressor: two spirals compress the air without lubricant in the compression chamber, with very low noise. It is the choice for laboratories, the medical and food sectors, and workshops with cleanliness requirements. In the AMES collection, power ratings run from 2.2 to 22 kW and above, the working pressure is 8 or 10 bar and cooling is always by air. For the higher power ratings or for heavy 24/7 use, it is also worth comparing a screw compressor.

The types

• Single scroll on base or skid: the basic version, with the scroll unit mounted on a frame. Fini offers them in the OS series, from small models such as the OS 2.2-08 up to larger sizes such as the OS 22-08.
• Tank mounted: scroll unit already installed on the tank, more compact and ready to connect.
• With integrated dryer: on the data sheets the entry reads "Yes" or "No". With the dryer, the air comes out already dry, suited to laboratories and delicate equipment.
• Pack, Full Feature and Twin: different configurations of the same unit, with different equipment and numbers of units. The data sheet states what each one includes.

How to choose by job

The features to look at

Power (kW). In the data: 2, 2.2, 3.7, 5.5, 6, 7.5, 11, 22 kW, with Fini models up to 30 kW. The small sizes are enough for a laboratory; the large ones are for several points of use.

Working pressure. 8 or 10 bar. For most uses 8 bar is enough; choose 10 if some users need more pressure.

Integrated dryer. If you do not get it with the compressor, you will need to provide for one downstream: condensate is unavoidable with any compressor.

Control. Electronic systems (Elektronikon Graphic) and electro-pneumatic controls are available: the electronic one is more convenient for monitoring pressure and maintenance.

Version and footprint. Skid, tank mounted, Pack, Full Feature, Twin; lengths run from 800 to over 2,000 mm. Measure the space before choosing.

Oil-free air. Oilless means there is no oil in the compression. If your process requires a specific purity class under ISO 8573-1, check the certification of the individual model.

How to approach the choice. Start from the type of air you need and the room it will be installed in: if air quality is critical or noise is a problem, scroll is the way to go. Then add up the consumption of the users running at the same time to find the power, and only afterwards choose the version (skid, tank mounted, with dryer) according to the space and the distribution network you already have.

Common mistakes

• Thinking that oilless means sterile air: filters and downstream treatment are still needed.
• Installing the scroll in a dusty or hot room, with the air intake near heat sources.
• Choosing the size with no margin: if consumption grows, the compressor always runs at its maximum.
• Forgetting the maintenance of the filters and the scroll unit at the hours specified by the manufacturer.
• Confusing maximum pressure with working pressure: read which of the two figures is given on the data sheet.

Frequently asked questions

Scroll or screw: which should I choose?

Scroll for oil-free air, low noise and moderate power; screw for high flow rates and very heavy continuous duty.

Do I need a dryer?

For laboratories, delicate instruments and paint spraying, yes. If it is not integrated, it must be installed downstream.

How quiet is it?

Very, compared with a piston compressor of the same power. The exact figure in dB(A) is on the data sheet of each model.

Can it be installed in a laboratory?

Yes, in a clean, ventilated room, with the air intake away from dust and heat sources.

You will find the models in the Scroll compressors collection: to choose the size and version, request a quote or ask the AMES technicians for advice.