Calculate the agent quantity for a total flooding system with the NFPA 2001 formula for clean agents (FM-200 / HFC-227ea and Novec 1230 / FK-5-1-12) or the NFPA 12 relation for CO₂, with net volume, minimum room temperature and altitude correction.
Enter the enclosure and click Calculate
Multiply W by the altitude correction factor (below 1.0 above sea level), then divide by the cylinder fill to get the number of containers. Use the lowest expected room temperature, because colder air needs more agent.
W/V = (1/S) × C/(100 − C) for HFC-227ea, sea level. Multiply by net volume to get kg. Highlighted: 7% at 20 °C.
| Temp (°C) | S (m³/kg) | 6.7% | 7.0% | 7.5% | 8.0% | 8.5% | 9.0% | 10.0% | 10.5% |
|---|---|---|---|---|---|---|---|---|---|
| 0 °C | 0.1269 | 0.5659 | 0.5931 | 0.6389 | 0.6852 | 0.7320 | 0.7794 | 0.8756 | 0.9245 |
| 10 °C | 0.1319 | 0.5444 | 0.5707 | 0.6147 | 0.6593 | 0.7043 | 0.7498 | 0.8424 | 0.8894 |
| 15 °C | 0.1344 | 0.5343 | 0.5600 | 0.6033 | 0.6470 | 0.6912 | 0.7359 | 0.8267 | 0.8729 |
| 20 °C | 0.1369 | 0.5246 | 0.5498 | 0.5923 | 0.6352 | 0.6786 | 0.7224 | 0.8116 | 0.8570 |
| 25 °C | 0.1394 | 0.5151 | 0.5399 | 0.5816 | 0.6238 | 0.6664 | 0.7095 | 0.7971 | 0.8416 |
| 30 °C | 0.1419 | 0.5061 | 0.5304 | 0.5714 | 0.6128 | 0.6547 | 0.6970 | 0.7830 | 0.8268 |
| 40 °C | 0.1469 | 0.4888 | 0.5124 | 0.5519 | 0.5919 | 0.6324 | 0.6733 | 0.7564 | 0.7986 |
| 50 °C | 0.1519 | 0.4728 | 0.4955 | 0.5338 | 0.5725 | 0.6116 | 0.6511 | 0.7315 | 0.7723 |
Lower temperature or higher concentration needs more agent. Above the 9% NOAEL, NFPA 2001 limits occupant exposure.
| Novec 1230 concentration | kg/m³ |
|---|---|
| 4.2% | 0.6099 |
| 4.5% | 0.6555 |
| 4.7% | 0.6861 |
| 5.0% | 0.7322 |
| 5.3% | 0.7786 |
| 5.6% | 0.8253 |
| 5.9% | 0.8723 |
| CO₂ concentration | kg/m³ (theoretical) |
|---|---|
| 34% | 0.761 |
| 40% | 0.936 |
| 50% | 1.270 |
| 60% | 1.678 |
| 65% | 1.923 |
| 75% | 2.539 |
CO₂ values are the theoretical free-efflux quantity. NFPA 12 design flooding factors for surface fires are higher, because they include leakage allowances and minimum quantities that depend on room volume, so use the NFPA 12 tables or the supplier's calculation for final design.
| Agent | Class A / electrical (typical design) | Class B | NOAEL | LOAEL | Occupied spaces |
|---|---|---|---|---|---|
| FM-200 (HFC-227ea) | about 7% | 8.5–9% (fuel dependent) | 9.0% | 10.5% | Yes, up to NOAEL |
| Novec 1230 (FK-5-1-12) | about 4.2–4.7% | 5.3–5.9% (fuel dependent) | 10.0% | >10.0% | Yes, wide safety margin |
| CO₂ | 34% surface fires; 50% dry electrical | 34% or more by fuel | — | — | No, lethal |
Typical values only. Use the design concentration from the system's UL/FM listing and NFPA 2001 / NFPA 12 for the specific hazard. Clean agents are not suited to deep-seated fires.
The same room with CO₂ at 34% needs about 68.5 kg theoretically before NFPA 12 allowances. To size the standby battery for the releasing panel, use the Fire Alarm Battery Calculator. For the wider design method, see the Fire Fighting System Design Calculation guide, and for complete drawings the Deluge Foam-Water System DWG.
NFPA 2001 gives W = (V / S) × C / (100 − C), where W is the agent mass in kg, V the net protected volume in m³, C the design concentration in % and S the specific vapour volume in m³/kg. For HFC-227ea, S = 0.1269 + 0.0005 × T, with T in °C.
At 7% design concentration and 20°C, the flooding factor is 0.550 kg/m³. A 90 m³ room therefore needs about 49.5 kg before any altitude correction.
Around 7% is common for Class A surface fires and electrical hazards. Class B design concentrations are higher and depend on the fuel, typically 8.5% to 9%. Always use the concentration from the system listing for your hazard.
Yes, at normal design concentrations. The NOAEL of HFC-227ea is 9.0% and the LOAEL is 10.5%. Above the NOAEL, NFPA 2001 limits exposure time and requires prompt evacuation.
For total flooding, W = (V / S) × ln(100 / (100 − C)), with S = 0.5079 + 0.0019 × T. At 34% and 20°C this is 0.76 kg/m³ before leakage allowances. CO2 at extinguishing concentrations is lethal, so it is only used in normally unoccupied spaces.
Air is less dense at altitude, so less agent is needed to reach the same volume concentration. NFPA 2001 applies an atmospheric correction factor, for example about 0.93 at 600 m.
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