Tank cleaning is nasty business. It requires a lot of time, resources, and labor. There are special permits and training needed. Often times you are wearing a hydro blast suit and spending the day in a cramped, hot tank. All around, it doesn’t sound like much fun. Luckily, I haven’t had to do much of it (or really any).
While it may not be much fun, it doesn’t mean someone doesn’t find it interesting enough to study academically. In 1959, Dr. Herbert Sinner, a former chemical engineer, first summarized the basic principles of cleaning. He noted four related factors to any cleaning scenario: temperature, time, chemical action, and mechanical force. The idea is that when any of these factors is reduced, it must be compensated with the increase of one or more other factors.
The pie chart illustrates what is known as Sinner’s Circle.
Washing dishes is a probably the easiest example of how these four factors interact. Think of all the ways you can remove food stuck to your dishes. You’ve probably noticed that hot water (temperature) is going to remove stuck food better than cold water. Adding soap (a chemical reaction) will make the process easier and sanitize the dish as well. Also, you can soak the dishes overnight to help remove food (time). Or you can scrub the dishes clean (mechanical force). If you try washing your dishes after dinner with cold water and little to no soap, it tends to take a lot longer and a lot more scrubbing.
Of course most of use a dishwasher these days which uses hot water, soap, force, but saves us the time from having to it ourselves.
Similarly, when it comes to tank cleaning, there are four typical ways of doing so (and putting them in the dishwasher is not an option): manual/scrubbing, boiling out/ fill and drain, spray ball, and rotary wetting.
- Manual cleaning or scrubbing often requires entering the tank and manually cleaning with a hose, pressure washer or scrubbing mechanism. This requires a lot of time, and mechanical force. It can also be the most dangerous.
- Boiling out or fill and drain method requires filling a tank or vessel with a concentrated chemical solution and then heating the tank to remove the toxins and residues. This requires a lot of water and chemicals, a lot of energy to heat the solution, and can take a long time to accomplish. Sometimes it takes multiple fills to get clean. This can keep tanks offline for a long time.
- Spray balls or rotating nozzles are designed to create a “liquid sheet” that erodes away residue while cascading the walls of the tank interior with chemical cleaning agents. These can take a long time and often require a lot of chemicals.
- A rotary wetting device typically consists of nozzles rotating on two planes, to create a fast moving full-coverage 360-degree chemical “wetting” pattern. Often times rotary wetting can be quicker than spray balls, but still require a lot of time and chemicals.
There is a fifth way of cleaning and it’s a little different: using impact. A rotary impingement tank cleaner is basically a small water cannon (for lack of a better term) that you hang inside of a tank. This process allows tank cleaning without confined entry (less time in hydro blast suit, which is always a plus), and uses less water, energy, and time.
This process is much more interesting to watch than to read about. Check it out in action:
What do you find is the best way to clean your tanks?