Tested my life jackets last night - failure...

[fisherman]

My previous to last lifejackets, post 2000 but not much, one inflated fine and stayed up, one had a rusty bottle and no response, and leaked as well. Both treated the same, and in the shed the last ten years.

 

[LittleSister]

Though it's probably the best we can do, I've always been a bit sceptical about the value of the 'blow up and leave overnight to see if it deflates' test for lifejacket bladders.

In real life, as I see it, the weight of the wearer will be trying to pull much of the inflated bladder underwater, while the water will be trying to force it out of the sea, therefore the pressure in the bladder will be significantly greater than simply fully inflating it without any load on it, and more likely to find leaks or burst seams. Does that seem realistic?

Assuming so, I wonder what an appropriate pressure would be to inflate an 'unloaded' lifejacket to better represent the demands of its 'loaded' use.

 

[LONG_KEELER]

Great thread.

I've decided to junk my lifejacket and buy new.

 

[PetiteFleur]

If I read that right, you blew an auto-inflate LJ up by mouth then dropped it in water and the auto-inflate mechanism fired and tried to blow it up again. I'm not surprised that it leaked!
Please forgive me if I misinterpreted.

Yes, you misinterpreted it - I blew it up by mouth, Left overnight and it leaked so repacked and then dropped in the bath. The 2nd one which deflated slightly, I repacked and dropped in the bath and it immediately inflated and stayed up overnight with no sign of leakage. I assume that it initially leaked through the manual blow up valve because I had not replaced the cap. Probably keep it as a spare.

 

[zoidberg]

I'm pleased to relate that the one-and-only time I needed a lifejacket to inflate, it did.
I'm VERY pleased to relate....

 

[awol]

In real life, as I see it, the weight of the wearer will be trying to pull much of the inflated bladder underwater, while the water will be trying to force it out of the sea, therefore the pressure in the bladder will be significantly greater than simply fully inflating it without any load on it, and more likely to find leaks or burst seams. Does that seem realistic?

Not really. Hydrostatic pressure would balance the air pressure and the volume and thus bouyancy would decrease. Why not use a bicycle pump (good for ~8bar) to overinflate a lifejacket to bursting point. Don't forget to video it for Youtube.

 

[LittleSister]

Not really. Hydrostatic pressure would balance the air pressure

Not for that portion of the lifejacket bladder in the air, rather than the water, presumably?

 

[srm]

Assuming so, I wonder what an appropriate pressure would be to inflate an 'unloaded' lifejacket to better represent the demands of its 'loaded' use.

I use a dinghy foot pump to inflate mine, with some cloth held around the junction of the two tubes to reduce air loss. This is better than inflating by mouth as it puts dry air into the bladder and (for me ) allows for a higher pressure. Inflate until the bladder is hard then check after 24 hours.

Not really. Hydrostatic pressure would balance the air pressure and the volume and thus bouyancy would decrease.

Only if fully immersed.

 

[awol]

Only if fully immersed.

...... and then you could see the bubbles