Remember to always choose the appropriately sized air compressor for your system as per NFPA 13 and your local code requirements.

Types of Air Compressors
Oil-free air compressors: These air compressors are typically quieter and are great for sprinkler systems. Also, they provide clean air, lowering the need for contamination maintenance.

Piston Air Compressors: These air compressors work by compressing air through a piston. They are reliable, and suitable for small or large sprinkler operations.

Tank-mounted air compressors: These have an air supply to quickly provide air. These are often vary durable and reliable.

Rotary screw air compressors: A high-efficiency compressor, which is great for larger scale fire sprinkler systems.

Mounting
Riser mount compressors are engineered to be fit directly onto the sprinkler riser, often above a pre-action or dry-pipe valve. To add, these compressors save space and costs, at the downside of being a bit noisier. Conversely, tank-mounted compressors come with a receiver tank, which acts as a pressurized reserve. These systems require more space, but have reduced noise levels compared to riser mounted tanks.

Device Capacity
According to NFPA 13, the air supply shall have a capacity capable of restoring normal air pressure in the system within 30 minutes. Your compressor’s capacity will be determined by the flow rate (CFM) of the compressor along with the pressure (psi) of the system.  Horsepower is not an accurate way to size the system, due to different compressor designs between manufacturers.

Energy Efficiency
Commercial air compressors for fire sprinkler systems have better flow rates and are much more energy efficient than typical retail systems. A higher energy efficiency means lower power usage and lower energy bills.

Automatic Draining
Air compressors may come with automatic drain valves, which automatically remove condensed moisture from the compressed air system. An automatic draining system can lower maintenance costs and mitigate the buildup of rust or contaminants in your system.