These larger diameters are effective because they reduce the loss of pressure as a result of friction that occurs when transporting significant amounts of water over long distances. A 15cm hose will lose 1 bar every 100m when flowing at 5,5001/m, while a 25cm hose won't lose the same pressure until flowing at 19,0001/m. So the longer the distance and the smaller the hose diameter the more pumps that are needed to maintain the pressure at the fire-fighting tip. In an ideal world all the equipment related to large-diameter hose would be standardised and interchangeable but, unfortunately this is not the case and the market can appear quite confusing. Let's look at some examples. In the US for instance we find that storz couplings are generally supplied with locks but, across the pond, in Europe they aren't. What's more, the locks on 15cm storz couplings in the US aren't always compatible across manufacturers.
展开▼
