SWG cell explosion

[ganselmi]

This happened to a friend of mine a couple of days ago, but i'd like to share with you his experience.
Notwithstanding I clearly have advised him to switch the SWG machine off while backwashing and rinsing the filter, my friend, not only has forgotten it but he also had the great idea to close all the cell bypass valves.
As a result after a few minutes the sgw cell exploded and it was a quite big explosion, fortunately he was far enough to not be invested by clorine gases, but .......
The cell container was made with a transparent plastic (about 8 mm thick) and it was impressing how it got destroied.
In the next days I'll post some picture in orr to let you figure it out.
So don't keep the bypass valves closed, never!!!!
Unless you are really sure that the SWG machine is powered off !

 

[jblizzle]

I do not even know what bypass valves are ... never had any. If the plumbing was done correctly, there should have been a flow switch preventing the cell from generating with no flow (unless that switch also failed).

I would be very interested to see some pictures of the plumbing (or what is left) to try to better understand what happened.

 

[ganselmi]

The plumbing has been done accordingly to the SWG instructions, the bypass valves are mainly required in case you need to remove the cell, i.e. during the winter I use it in order to remove the cell and keeping the pump running for 1 hour/day.
Tomorrow I'll take some picture of plumbing and cell.

 

[Christian]

Should be interesting to see some pictures. Never heard of an SWG cell exploding like that before.

 

[Qwaxalot]

Should be interesting to see some pictures. Never heard of an SWG cell exploding like that before.

I have, it turned out that the flow sensor was outside of the bypass, DOH

 

[Christian]

I have, it turned out that the flow sensor was outside of the bypass, DOH

Ouch!

 

[jblizzle]

Should be interesting to see some pictures. Never heard of an SWG cell exploding like that before.

I have, it turned out that the flow sensor was outside of the bypass, DOH

That is what I am guessing in this case as well.

 

[ganselmi]

As promised. here a couple of pictures of the cell and plumbing, the Compupool unit is supposed to have an internal water fault sensor but it looks like not working as you can see.

 

[JamesW]

A mixture of hydrogen gas and chlorine gas can explode from blue light or uv, like from sunlight. I would avoid a clear cell.

 

[chiefwej]

So even though it's possible that a SWG cell can explode, it requires a lot of stupid mistakes to combine to actually make it happen. You have to power the SWG with no flow, (so the flow sensor has to fail, be bypassed or installed wrong) and you have to seal up both ends of the cell tight enough to contain the pressure of the gas being generated. That requires a whole lot of either carelessness or intential dumb decisions.

 

[JoyfulNoise]

So even though it's possible that a SWG cell can explode, it requires a lot of stupid mistakes to combine to actually make it happen. You have to power the SWG with no flow, (so the flow sensor has to fail, be bypassed or installed wrong) and you have to seal up both ends of the cell tight enough to contain the pressure of the gas being generated. That requires a whole lot of either carelessness or intential dumb decisions.

Hey Chief, don't the fire fighters / hazmat guys train for something called BLEVE - Boiling Liquid Expanding Vapor Explosion?

Maybe SWG owners need some BLEVE training video

 

[JamesW]

There's no need to seal the ends of the cell. The gasses just need to build up in the system somewhere. Then you need something to detonate the mixture of gasses.

In my opinion, the hydrogen gas by itself is probably not causing the explosion. I think that it's the combination of chlorine gas and hydrogen gas that creates the hazardous condition. The two gasses together are much easier to detonate than hydrogen by itself.

Cell explosions are rare, but they do happen.

 

[chiefwej]

Well I just read a thread started by someone who had a SWG that had been running for quite sometime with the cell energized at all times, yet no explosion.

problem.......... solved.

 

[jblizzle]

I think the build-up is more possible with the cells that have the entrance and exit on the bottoms like in the OP.

Still this is all extremely unlikely.

 

[JamesW]

Exploding pool!!!!!!

Even if the gasses build up, there needs to be something that ignites the mixture. Exactly what ignites the mixture when it does explode is still not well understood.