MMA tank evacuation in California. Technical explanation. An answer to 10 different assumptions in different threads.

[Melon]

I work in chemicals and have spent time in a methyl methacrylate plant. This is MMA. It’s downstream from either acetone or more likely propianaldehyde. In the US, this is downstream from Ethylene cracked from gas.

This is the product that’s made into acrylic. All of those clear plastic screens in front of the grocery checkout are acrylic. It’s also the thick plastic used in large aquariums, bullet proof glass etc. It’s lighter than glass, safer, and at a high level doesn’t involve strip mining to produce. It’s not consumer plastic attributed to most pollution like plastic water bottles.

MMA improperly stored or having a contaminant in the tank can cause polymerization. The liquid is basically cross linking in the tank to transform into another chemical. The waste product to that reaction is heat and pressure. This is what’s happening.

The tank is too far gone and is exponentially building heat and pressure. They can cool the tank but not stop the reaction. At some point the tank can’t handle the pressure and will rupture or explode. At this point, for safety, it’s best to turn on the hoses and back all emergency crew away. There iso no stopping it. The relief valve is either broke or more likely can’t keep up with the pressure.

I will answer questions if I know the answer. I was and am not a chemist or operator.

[BlueWaveNeverEnd]

1. Im less than 10 miles from the tank

[Melon]

4. On a relative basis... that's quite a ways.

I’m not sure of the evacuation zone. If your down wind, it could be prudent to leave. The solution to pollution is dilution…..the exposure 2 miles away maybe sufficient to dilute the toxicity. I’m not an expert here because this situation, though traumatic is relatively rare. I’ve seen it occur in a tank 1 time and in a few drums. None of those ended exploding or leaking and they were with a product called VAM. .

[IcyPeas]

2. Thanks.

One question (hope it's not too stupid)..

Regarding the water spray... is that spray carrying any toxins?

[Melon]

3. The water be sprayed on the tank is to dissipate heat.

The tank is most likely going to burst. The volume of material is increasing and becoming very hot.

Early in this. Prior to the relieve valve being plugged. A remedy could have been to puncture the tank. Ie. drive a pipe through the wall of the tank or have more of a controlled spill. It’s too dangerous now.

The tank is in a cement tub. It’s designed for contaminant of spills and likely drains to a holding area or tank. It won’t hold the full tank or contain an explosion.

MMA is toxic. It doesn’t cause cancer. But you don’t want to be exposed to it or breathe it. It can cause things like nerve damage. If you’re close….leave. It’s really not worth it and the firefighters can’t stop what’s going to happen. If they cool the tank enough, maybe a small leak will occur like the relief valve on a pressure cooker. But it can just explode.

[IcyPeas]

7. Local NBC news is saying it has cooled significantly

Should normally be 50 degrees

Currently 60 degrees

Earlier today it was up to 95 degrees

[Melon]

8. With the volumes that the chief is giving. I don't think it will rupture. There is room in the tank as long as

The pressure relief valve is open.

[Melon]

9. This is likely Celsius. Those number on are cold in F. A polymerization will heat a tank over 200F.

[eppur_se_muova]

17. The runoff will surely be somewhat toxic. That is not to say that it is anything like the greatest danger involved. nt

[MerryBlooms]

5. Found live feedon YouTube, Garden Grove CA

[orleans]

12. the live streams i'm seeing on youtube are filmed in daylight and it's one thirty in the morning in chgo

so it's not that "live"

[Melon]

6. I just retread an article listed on the volumes.

The overall tank is 34,000 gallons. That’s slightly over a rail car of material. A rail car holds approximately 4 tanker trucks of volume to give you an understanding. The tanks can never be absolutely full.

The fire chief says that they could have a 7,000 gallon spill. That is one tanker truck. It may sound like a lot but that is not huge. It could also mean that the tank is only 1/4 full.


I would think that if that is the case. 1. The tank containment area should hold most of the spill unless it violently explodes. 2. There is a chance that the pressure bleeds with a small rupture and does not explode.

My assumption is on the volume in the tank. I could be wrong if the tank is actually full but the safety folks think that 1/4 the material would spill in a rupture. I don’t know how the chief is getting his numbers.

[C Moon]

10. Thanks for this!

[msongs]

11. one notices both tanks are installed in cages with sprinklers systems bathing them so this

is a known hazard and possibility

[druidity33]

13. Are we talking explode like...

the chemical being created is actually EXPLOSIVE? Or is this a pressurization issue, ie. expansion? Can't they throw a big fire blanket or net over it to contain the debris?

[Melon]

14. It's a pressure issue.

I don’t believe it would involve fire. MMA is highly flammable, but a flame would need to be introduced.

I believe I’d had spoken somewhere that I’ve been around for maybe 3-4 of these in the past. Mostly in drums. None of those ended in a disaster. They used water to cool the reaction. Before it got out of control on a few of them, they were able to add more inhibitor in the material and stop it as low the reaction or the vessels simply swelled and didn’t breach. I was told of events where especially drums will swell and explode like a d sad mall bomb but have never seen the aftermath.

The issue is that once polymerization hits 20% of the material in the tank, the reaction is out of control so you should get away from it. They are too dangerous to approach. At some point the reaction consumes the chemical and it slows and stops. These all don’t end bad.

[mopinko]

15. what about a blast mat?

i used to work construction. 1 of the jobs i was on involved blasting limestone layers. they used a huge, heavy mat, basically heavy duty chainmail.
i have no idea if 1 is available w/in a reasonable distance, but they def r a thing.

(the boss’s idiot son was in charge of the dynamite. the 1st blast he did, he used about 3 times what was needed. the blast mat went about 30’ in the air. every car in the parking lot was damaged. lol. after that it was my sad duty to watch him.)

[Melon]

16. I've never heard of one being used.

I’ve seen where a bulldozer will push dirt around a drum etc. when the tank breaches, it’s not likely to be a major event I believe. The term explosion is probably to extreme.

The vessel will breach. It’s not designed to for to high of pressure. Scaled or seen may fail. You don’t want a lot of MMA in the air next to high population, but it’s not going to wipe out structure nearby and break windows….i think.

The fire chief said 6500 gallons. It’s literally a tanker truck. It’s not good, but it’s also not that bad. This material is transported in trucks on the road everyday. There absolutely have been spills etc that are cleaned up with zero incidents and they aren’t in the news.

[IcyPeas]

18. Firefighters are approaching the tanks. Perhaps to see the temperature gauge.