Reprinted from the ACJ - April, 1993
I was watching one of my favorite intellectually stimulating informative documentaries on TV the other day. It is about this family that strikes oil in Tennessee and then moves to Beverly Hills because they are so wealthy.
Maybe you have seen it on PBS? Anyway, Granny was out by the cement pond stirring a large pot over a fire with a paddle, making lye soap. Had she been tending a three row core instead of animal fat in that pot, she would have had the basic ingredient of a radiator shop: the boilout tank.
The boilout tank used to be part of the definition of a radiator shop. But the increasing role of aluminum in the market and the ever-growing regulation of hazardous materials and waste has limited the shop's dependence on the boilout tank. Because of this, the hazards and necessary safety considerations may have fallen from the front of your mind. Let's bring them up again.
It is hard to think of a more hazardous setup. A large open tank filled with sodium hydroxide solution, kept at a temperature just below boiling.
Sounds like medieval torture apparatus. Chemically, sodium hydroxide, also called caustic or lye, is a severely corrosive material that can blind a person in a single splash. It is also a poison if swallowed, and can cause some of the nastiest deep penetrating ulcer type burns on living tissue.
When Granny was making her lye soap, she would place animal fat in the hot caustic to allow the lye to attack and react to form "soap" molecules. If you have ever had caustic on your hands, you noticed that it feels slippery. This is because the caustic is pulling the fat out of your skin and making soap out of it, thus the slippery feeling.
Just imagine if someone were to slip and fall into the tank. I think I saw that in one of the "Friday the 13th" movies. Of course, that guy went on to
make several more sequels, but most folks wouldn't be that lucky - he probably has a good agent. It's a dangerous situation and caution is required.
Another wrinkle in the boilout story is the fact that the solution is heated. Almost all chemicals react more aggressively when heated. Caustic will cause a burn at room temperature, but can cause severe rapid burning at elevated temperatures.
Some physical hazards associated with the tank are also present. When caustic is added to water, it will react, may spit and will generate heat due to the mixing process. It's called "heat of dissolution."
So use the same protective equipment when recharging your tank as you should use when working over it: gloves, goggles and an apron. A full face shield is not a bad idea.
Because of the "basic" nature of sodium hydroxide (high pH), it will react violently with acids. Be careful not to mix these two.
If for some reason you used acid on a core prior to boilout, make sure you rinse it out first. A little acid trapped in a core tube that contacts the caustic solution can cause enough pressure to rupture the tube. Half a core filled with acid dunked into the boilout tank could cause a serious explosion.
Aluminum cores and boilout tanks don't mix. The aluminum dissolves rapidly, destroying the core. In addition, hydrogen gas (H2) can be released in substantial quantities. If this gas finds an open flame - picture the Hindenburg. It was filled with hydrogen.
So what have we learned? That lurking in your shop is a medieval torture chamber, bubbling away, just waiting for the chance to suck you in and turn you into Ivory soap. That may be a bit drastic, but a good deal of care should be taken when working around that cornerstone of the radiator shop, the boilout tank. Always think safety.
The solution must be strong and aggressive if it is to cut through the buildup inside a dirty radiator. If it can cut that scum, it certainly can damage your skin and eyes.
Well, I see the next installment of that documentary is starting. It's the one where Jethro becomes a big-time Hollywood producer.
The above article was written by David M. Brown, Chief Engineer of Johnson Manufacturing Company, Inc. and is published by JOHNSON with the expressed approval of the National Automotive Radiator Service Association and the Automotive Cooling Journal. Other reproduction or distribution of this information is forbidden without the written consent of JOHNSON and NARSA/ACJ. All rights reserved.
JOHNSON MANUFACTURING COMPANY
114 Lost Grove Road / PO Box 96 / Princeton, Iowa 52768-0096
Phone 563-289-5123 or Fax 563-289-3825