Compressor Dry System Capacity Calculator

Compressor Dry System Capacity Calculator^©

Enter the maximum air pressure (PSI) and the volume (Gallons) of the dry portion of the system to determine which compressor best suits your needs. This calculator helps you comply with NFPA 13 requirements by identifying air compressors capable of restoring normal air pressure in your dry pipe, preaction, or deluge system within the required 30-minute timeframe. For buildings with multiple dry systems, the largest system size will determine the compressor's required capacity rating, as each system is filled one at a time and the 30-minute fill time requirement applies to each system separately. Simply input your system specifications, and the tool will recommend compatible C-Aire fire protection air compressors from our capacity ratings table, ensuring optimal performance for your fire sprinkler system.

Dry Pipe, Preaction, & Deluge Valve Air Pressure Lookup Tool^©

Select your fire sprinkler dry pipe, preaction, or dry-pilot-actuated deluge valve brand, model, and max static water pressure to determine the recommended air pressure range (PSI). According to NFPA 13, the system air pressure must be maintained per the dry valve manufacturer's instruction sheet, or set to 20 psi above the calculated trip pressure based on the highest normal water supply pressure. The recommended air pressure range determines the minimum and maximum settings of the air maintenance device (CAMD1), preset pressure switch, or digital pressure switch (Digital AMD). This ensures your dry system maintains proper supervisory air pressure and trips correctly when activated. Note that NFPA 13 requires air compressors with a flow capacity exceeding 5.5 CFM at 10 PSI to have an air storage tank and an air maintenance device, while compressors with a flow capacity below this threshold do not require an AMD or a tank. For dry valves equipped with an accelerator (quick-opening device), tank-mounted air compressors are strongly recommended as the tank provides a stable air supply buffer that prevents momentary pressure fluctuations from causing false trips of the accelerator. Accelerators may also affect the recommended air pressure. Always consult the specific valve manufacturer's instruction sheet for precise air pressure requirements and installation guidelines.

HOW TO SIZE

NFPA 13 Requirements: According to NFPA 13, the air supply shall have a capacity capable of restoring normal air pressure in the system within 30 minutes (NFPA 13 8.2.6.3.2). Additionally, air compressors with a flow greater than 5.5 CFM at 10 PSI require a tank and a regulator-style air maintenance device with a bypass and restrictor (NFPA 13 8.2.6.6). NEW for the 2025 edition of NFPA 13: Where an air compressor is dedicated for the sprinkler system, the air compressor shall be listed for fire protection (NFPA 13 8.2.7.5.2). C-Aire's listed fire protection air compressors are ETL Listed to UL Standard 1450 & CSA Standard C22.2 No. 68 and have been evaluated for fire sprinkler use according to UL 1450, Supplement SC, when installed in accordance with NFPA 13, "Standard for the Installation of Sprinkler Systems".

Dry System Air Pressure (PSI): An air maintenance device regulates the supervisory air pressure in a fire sprinkler dry pipe system, preaction system, or dry pilot-actuated deluge system. The system air pressure shall be maintained as per the instruction sheet furnished with the dry pipe valve, or shall be 20 psi above the calculated trip pressure of the dry pipe valve, based on the highest normal water pressure of the system supply (NFPA 13 8.2.6.7.1). View our Dry Pipe & Preaction Valve Air Pressure Range Finder to determine the recommended air pressure range.

Single vs. Multi-Valve Systems: Single-valve dry sprinkler systems are compatible with all fire protection air compressors and require an air maintenance device or pressure switch (Digital AMD Gen-3) to control the system pressure. Multi-valve dry sprinkler systems are only compatible with tank-mounted air compressors and require an air maintenance device before each valve. For a more detailed breakdown, view our Best Practices diagram here.

Size of the Largest System (Gal): While there is technically no restriction on the number of systems one air compressor can serve, the typical recommendation is one air compressor per three systems. The largest system size will determine the number of gallons for which the air compressor needs to be rated (capacity rating). Each system is filled one at a time, and the 30-minute fill time requirement applies to each system separately.

Compressor Dry System Capacity Rating (Gal): The compressor's dry system capacity rating is determined by the flow rate (CFM) of the compressor and the system pressure (PSI). Note: Horsepower is not a reliable method for sizing a compressor for a fire sprinkler system because each manufacturer uses different components, which can cause the horsepower to vary at similar system capacity ratings.

Other Manufacturer Equivalent: If you are looking to replace an existing air compressor from another manufacturer, use our new Competitor Cross Reference Tool or contact our customer service team, which is here to help you find the properly sized C-Aire compressor alternative.

C-Aire Dry System Capacity Calculator: Enter your provided PSI (air pressure) and gallons to determine which compressor best suits your needs. This calculator helps you comply with NFPA 13 requirements by identifying air compressors capable of restoring normal air pressure in your dry pipe or preaction system within the required 30-minute timeframe. Simply input your system specifications, and the tool will recommend compatible C-Aire fire protection air compressors from our capacity ratings table, ensuring optimal performance for your fire sprinkler system. View the Dry System Capacity Calculator here.

OTHER FACTORS

Type of Environment: Settings such as nursing homes, churches, and apartment buildings may need an oil-free compressor to avoid noise disturbances during operation. Oil-free compressors (Light Duty Series) are a suitable choice for quiet settings and require minimal maintenance. For older systems or applications where noise is not a concern, oil-lubricated compressors (Heavy Duty Series) are recommended as they are built for longevity and provide the lowest total cost of ownership over the life of the building.

Electrical Requirements: Electrical issues are among the most common troubleshooting topics related to air compressors. The electrician should thoroughly understand the electrical configuration and requirements of the compressor and the incoming power supply before installation to avoid potential problems for fire protection contractors later on.

Quick-Opening Devices (Accelerators): For dry pipe valves equipped with an accelerator (quick-opening device), tank-mounted air compressors are strongly recommended as the tank provides a stable air supply buffer that prevents momentary pressure fluctuations from causing false trips of the accelerator.

Cold Storage Systems: Dry pipe systems are prone to corrosion, in part, due to moisture in the air produced by the air compressor. Regenerative drying air compressors (Dry Air Series) are specifically designed to prevent corrosion by drying system air to a dewpoint of less than -40°F, thereby preventing the formation of dangerous ice plugs in cold storage systems. Per NFPA 13, normal system air pressure in cold systems (spaces below 5°F) shall be permitted to be restored within 60 minutes, instead of 30 minutes (NFPA 13 8.2.6.3.2). C-Aire's Dry Air Series compressors (R900 & R1700) are FM Approved for use in dry pipe and refrigerated area sprinkler systems.

Maintenance: All air compressors require regular maintenance to ensure optimal performance. As mentioned above, oil-free compressors are low maintenance but do not last as long as oil-lubricated compressors. Having a proper maintenance plan for your air compressor is an essential part of any dry pipe fire sprinkler system. C-Aire has a Twin Cities-based service team with over 50 years of combined experience that will solve your service needs and help with your compressor maintenance.