The short answer is YES.
Please learn from my mistake.
I usually have 1 between cell and bubbler then another between bubbler
and whatever the pipe is leading to.

During recent testing I had neither coupled up.
Like a fool I assumed the bubbler would protect as there was no chance of a missfire
(working on the bench)

Cell was going nicely/plenty of quality bubbles @ 15 amps.
Door was open and the window for plenty of air circulation.

Had some soldering to do which required the gas pen type torch.
To say I was suprised was an understatement.
nearly c****d myself.

I wasn't even working on the same bench as the cell/bubbler.

Appears bubbler went off and a chain reaction through the water allowed it to flash back into the cell which had a couple of inches head room for gas build up.

Highly inpressive but not what I had intended.

Let this be a lesson.
You can never use too many safety devices.

Dave aka coalman.