I have just finished cleaning up after a braided flexible connector (raccord flexible tressé) self-destructed under the kitchen sink.
I don't know if these things have a recommended working life. Scanning the Web, it seems that some people think that failure is rare, while others report multiple occurrences.
Fortunately, my failure happened as I closed the tap and I was able to turn off the main stop valve quickly. But I hate to think what would have happened if I had been out shopping, in bed, or away on holiday.
French plumbing works at a higher pressure than in the UK, thanks to the wonderful "chateaux d'eau". Water is delivered at at least 3 bars, but can go up to 7 bars if you have an electric water heater. Inside the braided steel, these things are only rubber and I just wonder how long they can be expected to last. Maybe the haven't been around long enough for anyone to know.
Fitting the replacement, I noticed that there is a tendency for the flexible to twist when tightening the connection to the supply pipe. If you are are doing a DIY job, I think it is important to make sure that doesn't happen.
So the lesson I have learned is, always turn off the main tap if I am away from home for an length of time and MAKE SURE THE HOME INSURANCE IS PAID UP TO DATE.
"If one calculates the forces acting on the inside of a 6mm flexible it's not much."
Can't argue with that, Vic, but it don't 'arf gush out when one splits! I was amazed to find that the steel braiding had also parted. I could not see any way that the damage could have been due to an external cause. I guess the technology of these is very similar to that in vehicle hydraulic systems. When those go wrong, it is normally due to external causes.
The one that went was on the hot side, as one would expect. I guess I should replace the cold one as well, to be sure,to be sure!
I don't know how familiar you are with French electric heating systems.
When you buy a new hot water tank here, they cannot sell it to you without a new "Groupe de Sécurité", consisting of a non-return valve, a drain tap and a pressure release valve that is factory-set to 9 bars.
As the valve opens, water can be seen dripping into a trap, from where it is piped away into the waste water system. The amount of expansion obviously depends on the initial temperature of the water. We normally only heat water at night. Our groupe de sécurité always drips when heating from cold. It must be intended to do this quite regularly, otherwise the trap would dry out, allowing foul air to escape from the drains.
Mike I am not sure you are correct re the pressure. The amount of pressure increase is way lower than 7bar. The blow off function of the pressure relief is their in case your thermostat packs up to prevent boiling water showering everything and everyone. I doubt heating the 3 bar supply (which you can reduce if not required ) would at 65 deg c be more that 4 bar (1 bar increase but possibly only 0.75 bar) Long time since I have worked through that equation.
I had some in the UK for I would suppose 20 odd years, still there when I sold up and left anyway. Like everything there is always a 'bad batch' and perhaps you got one of those. We had incredibly high pressure there and when hot water came out of either the kitchen taps or bathroom wash basin it was scalding in seconds with a 6m and 8m run to the heater, such was the pressure. So, I have had good experience with them, even though installed by me.
You can reduce the pressure at which the water arrives, but heating increases the pressure in the system to 7 bars before the pressure release activates. Explains why the water often arrives with a rush first thing in the morning. Unfortunately, heating water at night (on cheap electricity) can delay detection. A clever dog might raise the alarm, but I don't think our SOB could be trained to do anything so clever!
Yes they don't seem to last very long at these pressures, which by the way you can reduce if you are not in a tower block. Brother in law had them blow over winter and a nasty surprise when they got back in the spring. fortunately the water was turned off but the pipes hadn't been drained.