The Hidden Danger of Cal-Hypo

[JoyfulNoise]

I wouldn’t use the auto ignition temperature as the measure. MEK and acetone are both considered flammable substances as their flash points are well below 100F. Chemicals with flash points above 100F are considered combustible. The definitions of combustible versus flammable are not exact in a scientific sense but typically one handles flammable substances with a lot more care than combustible substance. Also, the auto ignition temperature changes when oxygen concentration increases but that’s because oxygen is the oxidizer for the reaction. Since chlorine/hypochlorite is a more powerful oxidizer than diatomic oxygen, one would expect a mixture of a flammable substance with air & chlorine to have a lower autoignition temperature.

Either way, I’d bet a box of donuts that the mixture goes boom .... maybe we can get the goofey YouTube guy that mixes trichlor and cal-hypo for fun to test it out ...

 

[PoolguyinCT]

I wouldn’t use the auto ignition temperature as the measure. MEK and acetone are both considered flammable substances as their flash points are well below 100F. Chemicals with flash points above 100F are considered combustible. The definitions of combustible versus flammable are not exact in a scientific sense but typically one handles flammable substances with a lot more care than combustible substance. Also, the auto ignition temperature changes when oxygen concentration increases but that’s because oxygen is the oxidizer for the reaction. Since chlorine/hypochlorite is a more powerful oxidizer than diatomic oxygen, one would expect a mixture of a flammable substance with air & chlorine to have a lower autoignition temperature.

Either way, I’d bet a box of donuts that the mixture goes boom .... maybe we can get the goofey YouTube guy that mixes trichlor and cal-hypo for fun to test it out ...

I know a kid that did that, he works for one of my competitors - cal & dichlor in bucket, when you stuck his stir stick in & broke the skin BOOM..

Hearing damage, burnt micas membranes & 2 night vacation in hospital..

Well he’s not a kid anymore & I’d say he is one of the best commercial / waterpark technicians in the tri state area.. he hangs 12” plumbing like a boss..

 

[JoyfulNoise]

I know a kid that did that, he works for one of my competitors - cal & dichlor in bucket, when you stuck his stir stick in & broke the skin BOOM..

Hearing damage, burnt micas membranes & 2 night vacation in hospital..

Well he’s not a kid anymore & I’d say he is one of the best commercial / waterpark technicians in the tri state area.. he hangs 12” plumbing like a boss..

Ahhhh the stupidity of youth....looks like we all managed to survive the good Dr. Darwin’s hypothesis....

 

[PoolguyinCT]

Ahhhh the stupidity of youth....looks like we all managed to survive the good Dr. Darwin’s hypothesis....

I actually don’t blame him one bit.. I have contempt actually disgust for his former employer for creating the situation and not providing the resources to operate safely.

In the old days CT had a low threshold to entry, today pool techs are licensed as individuals not entities.

 

[LTPOrangePool]

Mods/JoyfulNoise- move this to where it needs to be, I couldn't find a more relevant thread, or delete, whatever.
I had a few bags of dry cal hypo out in a Florida garage, they are about 8 months old.
They get plenty of ventilation, but there is plenty of humidity.
I check them every couple of months for storage.
I had 4-5 bags in an open dry cardboard box. I'm assuming a couple of the bags off-gassed somewhat.
A few of the original bags were melting together where they were touching.
I moved them apart and barely tore one bag, decided good time to shock the pool.
Probably about 1/2 tsp of granules on the clean painted garage floor.
That was yesterday. Today I thought to wipe up the granules.
I used a paper towel, and the cal-hypo had already pulled enough moisture out of the air to turn into liquid when touched.
I wiped up everything, went outside with the paper towel and felt it getting hot.
Set it down and it started smoking. I washed my hands and rinsed the paper towel out.
I know full well that it is exothermic.
If I let it, I'm sure it would have combusted. Maybe there was some oil on the paper towel but didn't look it.
I'm not sure if being in a plastic airtight pail would be any better, probably not coming in the house.
So kids, if you get a bunch of cal-hypo, don't just throw it anywhere.

 

[poolnoobgrandma]

UPDATE: Second fire breaks out at Lonza chemical warehouse in Bradley County - WRCBtv.com | Chattanooga News, Weather Sports

While I certainly advocate the use of cal-hypo when it can be substituted for liquid chlorine, it is a good reminder to treat it carefully. Cal-hypo can come in several different concentrations (% available chlorine) with 74% often easily obtainable. The downside to cal-hypo is that it emits chlorine vapors even in dry form and those fumes can act as a source of oxidation which can cause fires if flammable substances are stored near it. There are plenty of documented reports of cal-hypo fires happening but we rarely hear about them. Of particular concern to me is that people will use cal-hypo but not use it appropriately and open themselves up to exposure. Most cal-hypo for retail consumer use is sold as 1-lb bags of dry powder (and the bags are perforated so that they can breathe/emit chlorine fumes). If you use cal-hypo, the correct way to use it is to use an entire package and not leave any opened but partially used packages lying around. Doing that is a recipe for disaster.

So, if you plan to use cal-hypo in your pool this season, please do so safely by following all labelled package instructions. Also, make sure you store any cal-hypo in a safe location where it can not easily get wet and keep it stored away from any flammable substances.

We bought a 24 pack of cal-hypo at the beginning of the COVID-19 ..stuff. It's stored high and dry. If I need to use it I always use a full bag. Thanks for the heads-up!

 

[JamesW]