Today, various types of compressed gases such as acetylene, propane, oxygen, nitrogen, helium, argon, and so on, are used across various industries. Filled into cylinders, these compressed gases may pose chemical and mechanical hazards depending on their properties. They are often explosive, combustible, poisonous, corrosive, or may offer a combination of all these hazards. Thus, their careful handling and storage is very important. This post specifically concentrates on hazards as well as safe storage of compressed acetylene gas cylinders along with some additional information.
How is an Acetylene Cylinder Different from Other Compressed Gases?
Compressed gases are mainly distinguished into three types – liquefied, gaseous, and dissolved. Acetylene is one of the most popular dissolved gases used today. Being chemically unstable, it can even decompose at room temperature if above 15 PSIG. Therefore, acetylene is compressed into a cylinder that has an inert, porous mass made of a calcium-silicate. This mass is saturated with acetone to help absorb the acetylene. When acetylene gas is introduced into the cylinder, it slowly dissolves into the acetone, which can easily absorb up to 8 times the quantity of acetylene compared to a mass without acetone. Typically, a compressed acetylene cylinder is designed to feature the materials in the below-given ratios:
- Porous Mass: 10%
- Acetylene Gas: 34%
- Acetone: 42%
- Saturation gas: 1%
- Free Volume: 13%
This combination allows acetylene to be stored in cylinders at high pressure without the danger of decomposition or detonation. To be safe during regular use, it is recommended to maintain the gas system pressure at a maximum of 15 PSIG.
Know About the Hazards of Acetylene Gas
Acetylene is one of the well-known fuel gases used across the world. It is also one of the dangerous gases owing to the following properties:
- Acetylene is unstable, which means it can be dangerous at high temperatures and pressures due to decomposition.
- Acetylene possesses a wide flammability range. The lowest flammability limit in air is 2.4%, whereas the highest is 83%. These flammability characteristics mean that any small gas leak could result in a possible ignition.
- Acetylene also has low ignition energy, which means it may ignite when there are low energy sparks from a source such as static electricity. This is also one of the reasons why acetylene cylinders are not transported in closed vehicles. In the past, there have been several reported accidents due to ignition of the acetylene by the electrical system of these vehicles.
Tips for Safe Storage of Compressed Acetylene Gas Cylinders
Owing to the above discussed hazards, it has become important to take special care while storing and handling compressed gas cylinders of acetylene.
- Acetylene cylinders must be always stored in the upright position with valve caps on.
- Take care to store small cylinders properly as they don’t have protection caps on them.
- Acetylene cylinders are not designed for use in environments where the temperatures may exceed 52ºC (125ºF). Above this temperature if it is filled to maximum capacity there is not enough room for the acetone and acetylene to expand inside of the cylinder.
- Always ensure that the manifold containing acetylene and oxygen cylinders are separated by a 5-foot-high-fire rated wall or at least 20-feet distance unless on a torch cart used for cutting and welding.
- Always store compressed acetylene gas cylinders in areas that are:
- Dry and well ventilated
- Equipped with firefighting equipment such as sprinklers
- Free from sources of ignition and heat
- Easily accessible, yet away from main traffic zones, elevators, or staircases
- Labeled with warning signs
- Avoid storing acetylene cylinders in any subsurface storage areas.
- All acetylene gas cylinders in storage or service must be secured to rigid structures or securely stored in racks, so that they do not fall under any circumstances.
- The valve of the compressed acetylene gas cylinder should be opened only one and a half turns. If you find it difficult to open the valve using a small wrench or the wheel then return the cylinder to where purchased.
- Always open the cylinder slowly to avoid any mishaps.
- Avoid storing the cylinder in below-freezing point temperature zones, because in such environments, acetone will be removed from the cylinders with the acetylene gas resulting in damage to equipment.
- Never attempt to transfer gas between two cylinders or refill them on your own. Always approach an authorized gas distributor to refill your acetylene gas cylinder.
- Avoid jarring or bouncing cylinders when in storage or use.
- Use only components and fittings approved by the Compressed Gas Association (CGA).
In addition to the above-mentioned safety storage guidelines, it is important that you source these cylinders from a reliable acetylene cylinder manufacturer. Acetylene gas cylinders are built in adherence to established standards such as CGA – G-1; G-1.2; G-1.6; G-1.9; G1.10, European Industrial Gases Association (EIGA) – IGC Doc 123/13/E, and National Fire Protection Association (NFPA) – NFPA Section 55 Chapter 15, 2016.