Damien (moderator and caravan service engineer) once explained the logic supporting hose lifing. A hose correctly packaged and stored has minimal deterioration. But once gas starts to flow its acidic nature combined with pressure starts to age the hose polymer. That’s why hose life tends to be quoted from install date not manufacturing date. Caravan makers carry out basic checks using gas, so for a new caravan hose life starts on completion of build. It’s easy to see why confusion exists as it’s totally the opposite to tyres.2019 pigtail still has 3 years of life assuming it was fitted in 2019, if it was fitted last year then (now) it starts from fitting date and not manufacturing date. IMO it was easier to go by production date, as it’s there on the hose, where as anyone can say oh it was only fitted last year (for hoses out of day that is)