Requirements for fire hoses are appropriately high. Ultimately, they are not only exposed to a range of hazardous factors during use, such as heat or aggressive substances, but also have to withstand both extreme water pressure and remain flexible at the same time. Another factor is the ground that the fire hose is pulled across – regardless of whether it’s plain asphalt or a carpet of broken glass. It must withstand all of this no matter the situation.
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In order for emergency personnel to be equipped for any situation, there is a total of about 20 fire hoses on board a fire engine, in various sizes: from narrow hoses with a diameter of 25 millimeters for small fires up to hoses with a diameter of 75 millimeters that are used during major fires. The water pressure that these hoses have to withstand is specified in fire hose regulation DIN 14811. The minimum bursting pressure – i.e. the maximum pressure that a hose has to withstand before it bursts – is 60 bars. This is the equivalent to thirty times the pressure of a car tire. However, this is far from the reality of the scene of action. Usually, firefighters use water pressure of between five and eight bars to extinguish fires.