Looking at this photo, I have to think the LDH is actually 250 mm, which is the usual hose combined with the Hydrosub 250 - as it can pump up to 8000 LPM at 10 AT. The smaller Hydrosub 150 - which has a much lower output rated at 3500LPM uses 150 mm LDH.
It seems the manufacturer model numbers reflect the hose diameter needed to move the volume of output over extended distances. Incidentally, FDNY have several 250s, but theirs are mounted on trailers rather than using a pod system. This approach - also common in the Netherlands too - improves accessibility to the waters surrounding the city when the bigger transporters might have limitations. In a recent video, the 10 inch hoses were rapidly converted via a wye reducer to multiple 5 inch lines, which are the usual hydrant supply hoses used by US fire departments.
It seems the manufacturer model numbers reflect the hose diameter needed to move the volume of output over extended distances. Incidentally, FDNY have several 250s, but theirs are mounted on trailers rather than using a pod system. This approach - also common in the Netherlands too - improves accessibility to the waters surrounding the city when the bigger transporters might have limitations. In a recent video, the 10 inch hoses were rapidly converted via a wye reducer to multiple 5 inch lines, which are the usual hydrant supply hoses used by US fire departments.
Added by Rob Johnson on 04 July 2024.