17 Nov Compressed Gases

The term “compressed gases” applies to those gases and mixtures of gases that are stored under pressure in cylinders. Because of the high pressures that exist within such cylinders, compressed gases are considered hazardous.

The Major Groups

There are three major groups that compressed gases are classified into: liquefied, non-liquefied, and dissolved.

Liquefied Gases

Under normal temperatures liquefied gases can turn into liquids when they are inside pressurized cylinders. At first the cylinder in question is filled mainly with liquid and gas only fills the space above the liquid. But as gas is removed, the liquid that was originally inside the cylinder evaporates to replace the missing gas and keep the cylinder’s internal pressure the same. This creates an equilibrium, maintaining a liquid-vapor balance within the container. Some examples of liquefied gases include: anhydrous ammonia, propane, chlorine, carbon dioxide, and nitrous oxide.

Non-Liquefied Gases

Non-liquefied gases do not become liquid when they are compressed inside cylinders. They are sometimes referred to as pressurized or permanent gases. Some examples of non-liquefied gases include: oxygen, helium, nitrogen, and argon.

Dissolved Gases

Unlike the first two major groups of compressed gases, there aren’t many common examples of dissolved gases, as they can be very chemically unstable. For instance, acetylene (the only common dissolved gas) can explode even at atmospheric pressure. Nevertheless, it can still be stored and used safely in cylinders if kept at a proper temperature and pressure. What makes this possible is porous fillers in the cylinders. Porous fillers are saturated with acetone and other solvent. Gases like acetylene can dissolve into the fillers, becoming stable.

Dangers of Compressed Gases

There are many reasons that compressed gases can be dangerous. To begin with, the high pressures inside the cylinders make them a hazard should they develop a leak or crack.

Even if the pressure inside a cylinder is relatively low, a leak or crack of any kind can allow gas to flow out of the container forcefully, creating an uncontrollable rocket or pinwheel situation that could cause severe damages or injuries to people in the area. In some situations, if the break in the container is big enough the pressure of the gases inside may cause the cylinder to burst open completely.

The type of gas the compressed gas is can also affect how hazardous it is. For instance, flammable gases like hydrogen and acetylene can burn or explode under certain conditions. Oxidizing gases (any gases that contain oxygen higher than atmospheric conditions, usually between 23—25%) can violently react with combustible materials and cause fires and explosions. Additionally, dangerously reactive gases that are exposed to even small pressure or temperature increases, or shock, can produce violent chemical reactions.

Other Risks

Many compressed gases are toxic and can cause health problems. The type and extent of the health risks depends on the type of compressed gas, its concentration, how long you are exposed to it, and the way in which you are exposed (inhalation, skin contact, etc.).

Compressed gases also carry corrosive hazards, meaning that they can burn or destroy body tissue on contact. They can also corrode metals. Some examples of corrosive compressed gases are: hydrogen chloride, chlorine, ammonia, and methylamine.

Finally, inert gases like neon, nitrogen, argon, and helium can cause injury or death if they are present in high enough doses to reduce oxygen levels. If such gases get the oxygen level low enough then people within the affected area may lose consciousness or even die from asphyxiation.

Be Prepared; Take A Course

At Creation World Safety, we want you to be as safe as you can be. That is why we offer a wide array of corporate safety training courses and employee safety training courses, including courses regarding compressed gases. Make sure your company has been properly trained on compressed gases and contact us today to schedule a class with an instructor.