Usage
Hard suction hose, also known as a suction hose, is a specific type of rigid fire hose used in drafting operations. When using this technique, the fire engine draws water for fire fighting from an unpressurized supply, such as a portable water tank, pool, or other static water source, instead of drawing water from a pressurized water supply, such as a fire hydrant. Under complete vacuum conditions, a pump can lift water 33.9 feet (10.3 m), but "no pump on a fire apparatus is capable of producing a perfect vacuum". Due to this limitation and friction loss, fire services do not recommend attempting to lift water more than 3 metres (9.8 ft).
Hard suction hose may also be used to connect a fire engine to a hydrant. This practice is common in Australia, but woven jacket fire hose is normally used for this purpose in the United States. Using hard suction hose in this manner requires that the fire engine be positioned carefully for the limited flexibility of the hose, and may require multiple firefighters due to the weight and bulk of the hose section. In certain circumstances, it may be possible to use hard suction hose to draft from a hydrant with adequate water supply but a low flow rate.
These hoses are built to withstand vacuum, rather than water pressure, abrasion, and heat. They are, therefore, constructed differently to the standard fire hose and have different end fittings. In the United States, they are standard equipment according to the National Fire Protection Association standards for fire engines. Since hard suction hose cannot be folded, it is typically mounted on the side of a fire engine, often opposite ground ladders. Such hose is used in both structural and wildland firefighting throughout the world.
Hard suction hose can also be used to extend the range of a water tender's dumping capability, if the fittings of the hard suction hose match those of the tender dumping water. This could be used to fill a portable dump tank not immediately adjacent to the water tender, from which another fire engine can draft. Since water movement during dumping relies on gravity, rather than mechanical pressurization, hard suction hose is useful for this task.
Read more about this topic: Hard Suction Hose
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