FOAM DELIVERY SYSTEM SEAL CONFIGURATION: NFPA GUIDELINES
BELOW SEAL APPLICATION
| (No Foam Dam Required) | ||||
| Seal Type | Minimum Application Rate | Minimum Discharge Time (min) | Maximum Spacing Between Discharge (Outlets) | |
| gpm/ft² | L/min·m² | |||
| Mechanical Shoe Seal | 0.5 | 20.4 | 10 | 130 ft (39m) |
| Tube seal with more than 6 in (152mm) between top of tube and top of pontoon | 0.5 | 20.4 | 10 | 60 ft (18m) |
| Tube seal with less than 6 in (152mm) between top of tube and top of pontoon | 0.5 | 20.4 | 10 | 60 ft (18m) |
| Tube seal with foam discharge below metal secondary seal* | 0.5 | 20.4 | 10 | 60 ft (18m) |
| * Metal secondary seal is equivalent to a foam dam | ||||
ABOVE SEAL APPLICATION
| (Foam Dam is Required) | |||||
| Seal Type | Minimum Application Rate | Minimum Discharge Time (min) | Maximum Spacing Between Discharge Outlets with | ||
| gpm/ft² | L/min·m² | 12 in (305mm) Foam Dam ft (m) | 24 in (610mm) Foam Dam ft (m) | ||
| Mechanical shoe seal | 0.3 | 12.2 | 20 | 40 (12.2) | 80 (24.4) |
| Tube seal with metal weather shield | 0.3 | 12.2 | 20 | 40 (12.2) | 80 (24.4) |
| Fully or partly combustible secondary seal | 0.3 | 12.2 | 20 | 40 (12.2) | 80 (24.4) |
| All metal secondary seal | 0.3 | 12.2 | 20 | 40 (12.2) | 80 (24.4) |
| Where the fixed foam discharge outlets are mounted above the top of the tank shell, a foam splashboard is necessary due to the effect of winds. | |||||
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