[kennymcmack]

We have a 1000 gallon tank of McGean CeeBee J-84AL, which is a 40% sodium hydroxide solution and a sequestrant. We do analysis on it per the manufacturers instructions every 2 weeks and we keep it and the sequestrant within the limits. We have an immersion heater that keeps the tank around 170 degrees F. We have a problem with some white mineral deposits building up on the entire heater. It got so thick one day that it just exploded. Luckily no one was around. Since then, we drain the tank more often so we can inspect the heater to be aware of the build up of deposits on the heater. We constantly have to chip off the deposits to prevent an explosion from happening again.

Would anyone know what this deposit could be? Has anyone had this experience before with heaters?

Thanks, Kenny.

[DrCMS]

Does the tank breath to air?

Why do you keep it so hot?

[typhoon2028]

Can you take a sample of the deposits and add it too some vinegar or other acid?

If it bubbles, it is probably carbonate.

Sodium hydroxide will absorb CO2 from the air and form sodium carbonate.

Also what chemical is the sequestrant?

[typhoon2028]

Also, what is the tank made of?

[kennymcmack]

The tank is made of 18 gauge 304 Stainless steel. I will try that vinegar test. I'm not sure what the sequesturant is. McGean just lists it as GO-2L. The tank is open to the atmosphere. It has an open top, so we can dip things for cleaning. The temp is hot because of the manufacturers recommendation.

Thanks

[typhoon2028]

Okay, an open air tank could be absorbing CO2

Please report back your findings.

What are you cleaning?

[kennymcmack]

we are mainly cleaning stainless steel valves and components. We preclean most items with a sand blaster, then a simple green parts washer before going into the sodium hydroxide tank. Some items may have some paint residue or grease/oil residue left on it. But the tank is kept in a fairly clean condition.

[eugenedakin]

Hello kennymacmack,

I believe that typhoon2028 and DrCMS are correct in their questions.

When exposed to atmospheric air, CO₂ is absorbed from the air into the liquid, and then Sodium Hydroxide (NaOH) reacts to form Sodium Bicarbonate. (NaHCO₃)

Sodium hydroxide used-to be the material that was inside the space suits of astronauts to remove the exhaled CO₂ within the space suits. 

Best wishes,

Eugene