SWG Explosions? Startup Recommendations & Powertab questions

[Guy559]

Thanks Jim. All excellent points. I cited 1.8x simply as the outcome from an appropriate (and very low) pump speed, not as the end state itself. I was pleasantly surprised that I was getting a fairly high flow rate at what I consider to be a low rpm w/ correspondingly low power draw. Very cool. Was surprised when pool tech had pump running at 85% for half the day, then at 75% the other half. Seems excessively high, especially since there was little to no plaster dust after they acid washed before fill...

Sounds like 'low and slow' is the way to go... and the dialing up toward full speed for selective cases, like vacuuming through skimmer line, etc.

 

[Guy559]

So...wanted to follow-up on this topic given that SWCG is actively producing now. Have taken Jim's (and others') approach: VSP at lower speeds running 24/7. In my case, small bump up to @60% for 4 hours each day.

I previously mentioned I have a CMP Powertab Ultra that PB installed downstream of the heater and SWCG that was used for pucks during pool startup (~5 weeks ago). That kept FC up while also getting CYA up.

Last Friday I used PoolMath to add 15 bags of pool salt in preparation for SWCG operation. Went great. Salt dissolved quickly and I've been playing with SWCG output percentage to work on dialing-in FC amounts.

One thing I did during last week of non-SWCG operation was to load water into the Powertab Ultra dispenser to see if water level would hold. It did. For the entire week the water level in the dispenser was just below the level of the sight glass.

Then, I started generating FC from SWCG. With tab dispenser located downstream from SWCG, the gas produced has accumulated in the dispenser and displaced all the water from it. Given that there's no ignition sources, I'm going with a previous response to just "leave it" in the piping. Have tried finding a dummy pipe to just have a straight run but no luck.

In short: seems gas IS accumulating in the CMP dispenser. No issues with this as long as there's no ignition source?

Thanks all. Just want to ensure I don't wake up to a half-emptied pool because the dispenser experienced rapid disassembly from the accumulated gasses.

 

[Newdude]

Have tried finding a dummy pipe to just have a straight run but no luck.

Make your own. It's 2 unions and 2 ft of pipe. You can whack the check valve between the SWG and tab feeder to kill two birds with one bypass stone.

No issues with this as long as there's no ignition source?

Is it no ignition sources, or no ignition sources *yet*

I'd whack the feeder for the sole reason that some amount of magic bubbles weren't making it to the pool. The *exactly how much* question would keep me up at night.

 

[JamesW]

A mixture of hydrogen gas and chlorine gas can be very volatile.

It does not require an ignition like hydrogen and oxygen gas.

All it takes is a hydrogen or chlorine radical produced at the plates to initiate and explosion.

29 atm = 426 psi.

LED light illuminate a small corked test tube of hydrogen and chlorine gas with no reaction; ultraviolet light causes an explosion that shoots the cork across the room.

 

[Guy559]

Make your own. It's 2 unions and 2 ft of pipe. You can whack the check valve between the SWG and tab feeder to kill two birds with one bypass stone.

Is it no ignition sources, or no ignition sources *yet*

I'd whack the feeder for the sole reason that some amount of magic bubbles weren't making it to the pool. The *exactly how much* question would keep me up at night.

@Newdude, I like how you think. Great point about the check valve -- was only there due to temporary puck feeder (to prevent back flow to heater)?

If you look at first post with photo, I'm also thinking that replacing could enable me to make a 90-degree turn out of heater rather than the relatively hard-180 currently in place. I'm sure 'any reduction in flow restriction' is a good thing, but does a hard-180 like that ACTUALLY make much of an impact?

Plumbers did a nice job with runs. Most drains/returns from pool have an initial 90-deg turn, then they heated and bent remainder of run, up until they 90'ed it to go above ground at equipment pad.

Side note: in related news, installed one of the flow meters recommended here at TFP. Pleasantly pleased to see flow rates are higher than I would have expected, even when running VSP at lower speeds (e.g., approx 40gpm at 40% speed).

 

[Guy559]

A mixture of hydrogen gas and chlorine gas can be very volatile.

It does not require an ignition like hydrogen and oxygen gas.

All it takes is a hydrogen or chlorine radical produced at the plates to initiate and explosion.

29 atm = 426 psi.

LED light illuminate a small corked test tube of hydrogen and chlorine gas with no reaction; ultraviolet light causes an explosion that shoots the cork across the room.

Love his smirk before using the blue laser...

So, as long as I prevent 242kJ/mol of energy required to break the chemical bonds, I should be good as-is!

 

[JamesW]

Cells have exploded and we have several threads where this is documented.

There is no definitive source of initiation, but I suspect that it is probably triggered by the production of chlorine radicals at the plate, which start the reaction.

 

[Guy559]

Make your own. It's 2 unions and 2 ft of pipe. You can whack the check valve between the SWG and tab feeder to kill two birds with one bypass stone.

Is it no ignition sources, or no ignition sources *yet*

I'd whack the feeder for the sole reason that some amount of magic bubbles weren't making it to the pool. The *exactly how much* question would keep me up at night.

PS - I did note that if I loosened the junction for the puck dispenser, I could rotate it 180-degrees so that the can is pointed downward, which creates a straight run for the gas to (basically) bypass the dispenser. Probably my best temporary fix until able to make a more lasting change.

 

[JamesW]

Explosion near the SWG

We were watching TV and heard a major explosion after exploring in the backyard I went into my pool equipment should and found about a 16 in PVC pipe shredded 8in on one side 8in on the other side of where my SWG Is located. I have no Idea what to think. It appears the SWG somehow was not...

www.troublefreepool.com

 

[Guy559]

Explosion near the SWG

We were watching TV and heard a major explosion after exploring in the backyard I went into my pool equipment should and found about a 16 in PVC pipe shredded 8in on one side 8in on the other side of where my SWG Is located. I have no Idea what to think. It appears the SWG somehow was not...

www.troublefreepool.com

Yes - read a collection of these that have been pointed to over the years. Seems that members have reported a few incidents in the past 10+ years.

In the military, we'd conduct a "risk assessment analysis" that would likely find that it's "unlikely" to occur but, should an incident occur, that it'd be very bad...

 

[Newdude]

I'm also thinking that replacing could enable me to make a 90-degree turn out of heater rather than the relatively hard-180 currently in place. I'm sure 'any reduction in flow restriction' is a good thing, but does a hard-180 like that ACTUALLY make much of an impact?

Nope. It only makes a difference on paper. How many other 90s you got including underground ? 39 ?

But.

You could slide the SWG and flow switch over and 90 the 180 for very little extra work/expense. I don't think there is enough meat on the left side of the flow switch to reuse the fitting but Ts are cheap so no biggie.

in related news, installed one of the flow meters recommended here at TFP. Pleasantly pleased to see flow rates are higher than I would have expected, even when running VSP at lower speeds (e.g., approx 40gpm at 40% speed).

I was taught to speak RPM and never learned to speak GPM. IMO it's like MPH and KPH. I call it 60 and the Canadians call it 100. Some purists will point out that 60 mph is actually 96.5 MPH but the reality is they are way close enough for most of us.

 

[Guy559]

I was taught to speak RPM and never learned to speak GPM. IMO it's like MPH and KPH. I call it 60 and the Canadians call it 100. Some purists will point out that 60 mph is actually 96.5 MPH but the reality is they are way close enough for most of us.

Or Betamax and VHS.

Guess it depends on what you're looking to measure. I find both rpm and % max rpm to be good for understanding how hard my pump is working. I simply chose % as it tells me a bit more regarding what the pump is up to.

On the other hand, gpm enables me to better understand what's actually occurring for a given pump speed. In other words, how much water is actually moving (output) at a given pump speed (input).