Life Sucks, Get a Vacuum Chamber

| September 22, 2013 |

Vacuum Chamber Freeze Dry Food

Vacuum chambers are used for a whole lot in our modern day world, but we seldom realize it. From food packaging, to industrial production, to outer-space product testing, the seemingly mundane vacuum chamber actually has quite an interesting résumé. A vacuum chamber works by removing air and gases from an enclosed environment by use of a suction pump. The result is a low pressure environment, which, as mentioned, can be desirable for several reasons. The chamber itself must be constructed out of a rigid material that won’t buckle or bend under the high stress of the difference in pressures inside and outside of it. Small chambers can actually be self-constructed if you know what you’re doing, but for any situation in which you’re going to need extremely low pressure, you’ll want something industrial, or at least professionally made; an improperly constructed vacuum chamber can be dangerous.

“OK, great… Why do I care?”

Today, home made, or at least use-at-home, vacuum chambers are often used by survivalists. Their main purpose is to freeze dry food. Freeze drying a food item is one of the most effective ways to store food for long periods of time and is therefore desirable as food for a disaster or emergency kit. In a nutshell, freeze drying a food item involves freezing the food as quickly as possible, and then letting all of the moisture leave the food. The dry environment created by this process halts the growth of bacteria and mold. The role of a vacuum chamber comes in during the sublimation process, the phase in which the water is removed from the food. Without a chamber, the process is relatively slow, it is also undesirable because the ice passes through its liquid phase. Ideally, the ice is brought directly from solid to a gas form as quickly as possible. A vacuum chamber accommodates this, and is ideal for survivalists looking to preserve their own food. For more details and an in-depth walk-through on freeze drying food, see this article.

“How can I make my own?”

Alright, now we’re talking! The first thing you’re going to need to do is find something that can function as your main chamber piece. The biggest consideration here should be size – you need the chamber to be big enough for whatever it is you plan to put in it. Note: Make sure there’s a little bit of room to spare – some substances expand when in the chamber.

For material you’re going to want something like aluminum or stainless steel; both of these will resist bending under pressure and also won’t absorb moisture that may be drawn out during the suction process. Lastly, a cylinder is the ideal shape to use a vacuum pump with.

In order to use the chamber easily, you need to have an open top. In most cases, the bottom of the cylinder is open as well. In order to seal the chamber, you’ll put a piece of the same or similar material that you used in making the cylinder on the top and bottom of it. When the vacuum starts to form, the ends will suction to the cylinder. Because there can be gaps and imperfections in the contact made between the cylinder and its ends, you may have trouble getting an airtight seal to form. A good way around this is to line the edges of the end of each cylinder with rubber, ensuring a good seal when you place the ends on.

Finally, you’re going to attach a vacuum pump. Drill a hole in the chamber itself or in the top end panel, then use rubber O-rings to attach the vacuum pump in an airtight fashion. I suggest cutting the hole in the top end, just because the cylindrical shape of the main chamber may make it more difficult to attach than if you’d used the flatter top end piece.

The pressures your chamber will experience will depend on the strength of the material you used and the pump attached to it. For freeze drying, you will need to have a chamber that can get below (133 x 10^3). When you first run the pump, you may find some imperfections that need sealing up, or that your pump setting is too powerful for the chamber material you used. In any case, don’t get discouraged; I wouldn’t call constructing one of these a “hard” project, but it does take some number crunching to get things just right.

Once you get the hang of it, feel free to try different designs and sizes for different purposes. Remember to always use a rounded base shape, however, as a this will get you the most strength out of a given material!

Category: Food And Water

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