3S-FIRESTOP

Spheres are typically used to store below ambient temperature liquids and pressurized gases such as ammonia, propylene, LPG, butadiene, etc. Most (or many) spheres operate at low temperatures with -50°C (-58°F) as a lower limit. Gases are stored under pressure at a temperature lower than their liquefaction temperature. Why a tank is spherical? The spherical shape allows even distribution of stress, therefore reducing the risk of fracture or failure. Since 'Leak before Failure' concept is used in the design, it presumes and ensures that primary barrier (tank shell) will fail progressively and not catastrophically.
What are the instruments used in spherical tank fire protection ?

Heat Detectors
Spot-type heat detector is not suitable for application at the spherical tank. Linear heat sensor cable is installed at each of circular water spray ring. As per norms of NFPA 15, the spacing between circular ring fulfills the spacing requirement between each linear heat sensor lines as per NFPA 72A as well. Protectowire has several models : PHSC Series, PLR Series, CTI Series with rated temperature choices : 68 o C, 88 o C, 105 o C, 138 o C and 180 o C .

Gas Detector
The gas detector model must match with the stored substance ie. Methanol gas detector for Methanol storage tank, combustible hydrocarbon gas detector for hydro carbon fuel storage tank. These gas sensors are having relay ouput for connection to FACP, analog 4-20 mA output to PLC / ESS, and RS-485 output.

Flame Detector
As most spherical tank is used for ammonia, propylene, LNG, LPG, butadiene and other hydrocarbon derivatives ; the most common flame detector used is UV/IR or IR3 type. FGD flame detector model is FlameSpec-UV-IR or FlameSpec-IR3. Flame detector can give faster response than any other type of detectors.

Deluge Water Spray
Water spray is used to cool the tank to avoid BLEEVE. Deluge is used to deliver water to the spray nozzles. The deluge is electrically actuated via Ex-proof Solenoid. All conduit fittings used is Ex-proof type as well.

Type of Spray Nozzle
Due to strong wind, the appropriate spray nozzle types are medium - velocity spray nozzle or high-velocity spray nozzle. Full-cone spiral (whirl) spray nozzle is not suitable due to smaller droplet size. The water droplets can be easily taken away by the wind. Reliable has medium - velocity spray nozzle model. Check this link for K-Factor & spray angle selection : https://www.reliablesprinkler.com/product/mv-spray-nozzle/