Have you ever wondered why bags of potato chips have all that air in the top of them? That air, despite what most people assume, is not oxygen. It is, in fact, nitrogen, and it’s there for two reasons: it keeps your chips from getting crushed into tiny pieces during transport, and to keep the chips fresh. The same thing can be done in large storage tanks. Called tank blanketing or tank padding, it’s done for several reasons.
What is Tank Blanketing?
Tank blanketing can very simply be defined as adding air or some other type of gas to the space at the top of a tank. This vapor space can be filled with oxygen, but there are some things that customers do not want exposed to oxygen due to the fact that it can cause oxidation or other issues. More commonly, nitrogen is used because it is an inert gas that will not interact with the things stored in the tank. It’s also fairly inexpensive and is widely available, making it an ideal choice to use in tank blanketing.
In addition to reducing oxidation and extending a chemicals shelf life, tank blanketing also helps prevent contaminants from entering the storage space. It does this by creating a very slight pressure inside the tank that presses outward on the sides of the container. This means if there’s a leak, the gas will be forced out instead of allowing bacteria, dirt, and other contaminants in.
Tank Design Requirements for Tank Blanketing
When designing tanks to make use of tank blanketing, a few things must be done. First, the tank must have a pressure relief valve. These valves need to be set to a pressure that’s high enough that it prevents oxygen from entering the tank, yet low enough that the valve will vent out nitrogen if the pressure within the tank gets too high. Poly Processing’s engineering team can assist with the proper relief valves for your system.
The other required part of a tank designed for tank blanketing is a sealed manway.
Poly Tech vs Competing Tech for Tank Blanketing
There are a few different reasons why polyethylene tank construction is the better option for tank blanketing than traditional methods such as using stainless steel or fiberglass reinforced plastic (FRP). While multiple options can work for tank blanketing, polyethylene is actually better because it can last longer and is more cost effective. Stainless is often considered a standard for the food industry, but it’s also very expensive. FRP, on the other hand, works, but it’s not nearly as robust as XLPE, which has a broader range chemically.