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Correct mixing vessels for Sulfuric Acid and HF
I am about to get into a line of cleaners for the truckwash industry. One such cleaner is aluminium brightener. It has two nasty components, HF and Sulfuric Acid.
I have a pretty good idea how to handle the HF (and I have a very healthy respect for how dangerous it is and the need for safety precautions). Looks like HDPE tanks are the way to go. My question is about the Sulfuric acid. When added to water, it becomes very hot. The literature says it is very exothermic. But how hot does it get? For example, how hot would a drum of 98% Sulfuric Acid added to 200 gals of water at ambient temperature get?
Is there a way to calculate the heat generated? The reason I ask: I am looking at HDPE tanks to mix these ingredients. HDPE tanks have a temp rating of 140 °F. I don't want the tank to melt. I can't go to a glass lined tank, because of the HF. Steel is out. Can anyone help?
Steve Garro
- Toledo, Ohio, USA
2005
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It will get a lot hotter than 140 &def;F. 200 °F is a strong possibility. The simple solution is to buy your sulfuric acid
[affil links] at a guaranteed lower concentration where you have to add very little water. Let someone else go thru the dilution grief.
The next option is a dilution room where you have stored enough that it has had time to reach room temp. You could use a stainless steel tank for this.
You can use ice, rather than water for most of your make up.
The poly tank needs to be very well reinforced. Consider a fiberglass laminated tank shell.
Have a very good product warning on the label and have lots of insurance. You have a higher than average probability of being sued. Consider a full incorporation and not a subchapter. Look into the owner protection offered by a LLC. It came about several years after I got out of the ownership bit.
James Watts
- Navarre, Florida
Hi Steve,
Many moons ago we used to sell Laurence Starch in Toronto some moulded Pe tanks ... but the exotherm did cause them to bulge! These were, of course, for sulfuric and yes, they did add that to the water. And they didn't fail but kept a permanent bulge.
There are, primarily in the USA, two different types of Pe. The regular medium density and the more expensive cross linked. But whether you can find your tank sizing in the cross linked I just don't know.
The cross linked CANNOT be welded. So any outlets should be CPVC or perhaps PP bulkhead adaptors ... but I believe that this material will withstand a much higher temperature than the regular Pe.
Re your question of What Would the Temperature Be? Ah, that depends on how quickly you add the acid, doesn't it, eh?
What about a trial run with the acid trickling in at a slow rate? Stick in a thermometer to find out what the temperature is. Buy a small moulded Pe tank and run an experiment.
Another thing that you might be aware of ... when dealing with the conventional Engel moulding process, you can, if you ask, have the wall thickness increased to max. 1/2". They just add more powder, that's all. That increases the safety factor a little.
![freeman newton portrait]()
Freeman Newton [deceased]
R.I.P. old friend (It is our sad duty to
advise that Freeman passed away 4/21/12)
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