Homemade Autoclave from a Gas Cylinder: Instruction

Every housewife probably dreams of making homemade preserves easily and deliciously. What could be better than a natural product without GMOs and other harmful chemicals?

Previously, this was a very complicated process: sterilization, boiling, canning, a lot of nerves, and the final result was not always satisfying. But times have changed, and the process can be significantly simplified. How? By making a homemade autoclave. In this article, you will learn how to easily make one using a regular gas cylinder. 

What is an Autoclave?

An autoclave from a gas cylinder is a device designed for thermal processing of raw food products in home conditions.
Structurally, it is a sealed container consisting of the following elements:

1. Body.
2. Pressure gauge.
3. Thermometer.
4. Release valve.
5. Valve nipple.
6. Lid.

This design allows combining two main processes: boiling and sterilization. Although the image above shows a factory sterilizer, after reading this article, you will be able to make it yourself at home using available tools.

How Does an Autoclave Work?

The entire technological process of making homemade preserves is divided into 8 stages:

1. A small amount of water (ideally 1-2 cm) is poured into a prepared glass jar.
2. Products for preservation are mixed with seasonings, placed in jars, and sealed.
3. The prepared jars are placed in the autoclave so that the upper parts of the jars are submerged in water by at least 1-2 cm.
4. Ordinary water is poured in without any preparation.
5. The lid is closed, and using a pump or compressor, a pressure of 0.1 MPa (1 bar) is created.
   IMPORTANT! The design must be airtight to maintain the necessary pressure!
   

6. The sterilizer (autoclave) is placed on a gas or electric stove. As the water heats up in the system for preparing the preserves, the pressure should increase to 3-4 bars.
7. After heating and creating the required pressure, cooking will take at least 20 minutes for fish, 30-45 minutes for pork, and 40-50 minutes for beef.
8. Next, the device cools down to room temperature, after which you can release the air and retrieve the finished product.

The main principle of operation is to increase the boiling temperature of water to 110-115 degrees Celsius by raising the pressure. As a result, the jars are sterilized and the necessary product is prepared simultaneously.
After discussing the theoretical part, let’s address the main question: how to make a homemade autoclave from a gas cylinder?

Which Cylinder is Best for a Homemade Autoclave?

The most suitable model is a 24-liter cylinder. It has ideal dimensions and allows you to cook 5-liter or 14-liter jars at the same time. You can use a larger cylinder (e.g., 50 liters) - its capacity will be greater, but it is inconvenient to use.
However, if you are skilled with electricity, you can make an electric autoclave from a 50-liter container by installing heating elements.

Homemade Sterilizer Manufacturing Technology

●       valve from a car tire;
●       M12 bolts with nuts.
Instructions

1. Preparing the Cylinder. The gas must be completely released, and the container should be blown with compressed air or filled to the brim with water. If the gas smell persists after rinsing, the container can be purged using a blowtorch or burner.
2. Preparing the Lid. The top part of the cylinder is cut off using a metal cutting wheel or a gas torch. It is better to make a rectangular cut for the subsequent mounting of flanges.
3. Preparing the Base. Legs made of 35 mm angle iron are welded to the bottom of the cylinder to provide stability to the structure.
4. Preparing the Connections. A neck made of 5 mm sheet steel is welded to the lower part of the cylinder at the rectangular cut location. Then, a previously made flange with holes for M12 bolts is welded to it.
5. Preparing the Openings. A hole is made in the lid. A pipe is welded to which a safety valve, ball valve (tap), and pressure gauge will be attached later. A hole for the thermometer is made in the center of the tank. A hole for a regular vent from a tubeless tire or chamber is drilled in the upper part of the vessel.
6. Gasket. A paronite or rubber gasket should be inserted between the flange and the lid, after which the upper and lower parts should be joined. Gasket dimensions: outer diameter – 18 mm, inner – 10 mm, thickness – 2 mm.
7. Checking for Leaks. After joining the two parts, use a compressor to create a pressure of 3.75 kgf/cm². It should maintain this level for at least 3 hours.
8. Checking the Safety System. Using a pump or compressor, gradually increase the pressure. When approaching 6 kgf/cm², the safety valve should activate and drop the pressure in the system.
9. Testing in Operation. At this stage, the device is loaded with cans and the functionality of the resulting product is tested
   IMPORTANT! The tubeless rubber valve and safety valve with pressure gauges can be located on either the lid or the cylinder. However, they must be positioned above the liquid level in the system.

As a result of the work done, you should end up with something like the photo below:

Electric Autoclave

The aforementioned boiler can also be upgraded. Simply insert heating elements with a power of 2-3 kW into the finished container. Additionally, automation elements should be added to enable switching heating on and off based on temperature and pressure.
However, homemade electric autoclaves have not gained widespread practical use as they are more complex to produce, and not everyone is willing to invest in automation for such autoclaves.
Safety Rules:

1. The water level in the autoclave should be 8-10 cm below the neck, as steam is generated during heating and pressure increases.
2. Continuously monitor the liquid temperature and pressure level in the vessel. When the temperature reaches 100⁰C, the gas can be turned off and just maintain the temperature.
3. The optimal working pressure is 3.75 kgf/cm². It is advisable not to exceed this threshold.
4. It is forbidden to open the vent for air release immediately after heating, as a sudden pressure drop will cause the cans to burst.
5. Air release is only allowed when the entire system has cooled down to room temperature. This process should be carried out gradually.

The autoclave made from a gas cylinder is relatively easy to create with the right tools, skills, and willingness. However, caution is necessary when operating pressurized vessels, as careless handling and violation of manufacturing technology can lead to accidents.
If this seems too difficult for you, it is better to purchase a factory-made home canning autoclave that has been tested and meets all requirements and standards. It also comes with detailed instructions on how to use the autoclave.

Also read:

• Autoclave Operating Modes
• What is an Autoclave
• Hydraulic Testing of an Autoclave
• How to Use an Autoclave
• How to Choose a Household Autoclave

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