vapour into the foam conveying This is a system for floating roof tank piping system. where the foam travels through a flexible pipe inside the tank upto the Where two or more pourers are center of the tank roof and exits at required these shall be equally the seal rim of the floating roof spaced at the periphery of the tank precisely where the fire is located and each discharge outlet shall be thus rapidly flooding the seal rim area sized to deliver foam at and quickly extinguishing the fire. approximately the same rate. 4.4.4 FLOATING ROOF TANK Tanks should be provided with foam PROTECTION discharge outlets/pourers as indicated below :- For floating roof tank, foam shall be poured at the foam dam to blanket the roof seal. Features of foam Tank diameter Foam Pourer system for floating roof tank ( In M) (Min. Nos.) protection shall be as follows :- 18 & up to 20 2 System be designed to create foam Above 20 & up to 25 3 blanket on the burning surface in a Above 25 & up to 30 4 reasonably short period. 30 & up to 35 5 Above 35 & up to 40 6 Foam shall be applied to the burning Above 40 & up to 45 8 hazard continuously at a rate high Above 45 & up to 50 10 enough to overcome the destructive effects of radiant heat. In case foam pourers are provided on tanks having diameter up to 18 Foam makers/foam pourers shall be m, minimum 2 nos. foam pourers located not more than 24 m. apart shall be provided. on the shell perimeter based on 600 mm foam dam height. The estimation of number of foam discharge outlet is based on pourer A minimum of two foam pourers capacity of 1000 lpm at a pressure be provided. of 7 kg/cm2 (g) upstream of eductor. This can be suitably adjusted for 4.4.5 FIXED ROOF TANK PROTECTION different pourer capacity in accordance with section 4.4.4 (iii). Foam conveying system shall have same features as of floating roof 4.4.6 FLOATING CUM FIXED ROOF tank excepting that a vapor seal TANK PROTECTION chamber is required before the foam discharge outlet. Protection facilities shall be provided as required for fixed roof tank. Features of the foam system for roof protection shall be as follows: 4.4.7 PROTECTION FOR DYKE AREA/SPILL FIRE The vapor seal chamber shall be provided with an effective and Portable monitors/foam hose durable seal, fragile under low streams shall be considered for pressure, to prevent entrance of
This is a system for floating roof tank where the foam travels through a flexible pipe inside the tank upto the center of the tank roof and exits at the seal rim of the floating roof precisely where the fire is located thus rapidly flooding the seal rim area and quickly extinguishing the fire. 4.4.4 FLOATING ROOF TANK PROTECTION For floating roof tank, foam shall be poured at the foam dam to blanket the roof seal. Features of foam system for floating roof tank protection shall be as follows :- System be designed to create foam blanket on the burning surface in a reasonably short period. Foam shall be applied to the burning hazard continuously at a rate high enough to overcome the destructive effects of radiant heat. Foam makers/foam pourers shall be located not more than 24 m. apart on the shell perimeter based on 600 mm foam dam height. A minimum of two foam pourers be provided. 4.4.5 FIXED ROOF TANK PROTECTION Foam conveying system shall have same features as of floating roof tank excepting that a vapor seal chamber is required before the foam discharge outlet. Features of the foam system for roof protection shall be as follows: The vapor seal chamber shall be provided with an effective and durable seal, fragile under low pressure, to prevent entrance of vapour into the foam conveying piping system. Where two or more pourers are required these shall be equally spaced at the periphery of the tank and each discharge outlet shall be sized to deliver foam at approximately the same rate. Tanks should be provided with foam discharge outlets/pourers as indicated below :- Tank diameter Foam Pourer ( In M) (Min. Nos.) 18 & up to 20 2 Above 20 & up to 25 3 Above 25 & up to 30 4 30 & up to 35 5 Above 35 & up to 40 6 Above 40 & up to 45 8 Above 45 & up to 50 10 In case foam pourers are provided on tanks having diameter up to 18 m, minimum 2 nos. foam pourers shall be provided. The estimation of number of foam discharge outlet is based on pourer capacity of 1000 lpm at a pressure of 7 kg/cm2 (g) upstream of eductor. This can be suitably adjusted for different pourer capacity in accordance with section 4.4.4 (iii). 4.4.6 FLOATING CUM FIXED ROOF TANK PROTECTION Protection facilities shall be provided as required for fixed roof tank. 4.4.7 PROTECTION FOR DYKE AREA/SPILL FIRE Portable monitors/foam hose streams shall be considered for