Compressed gases are a vital part of many industrial processes and must be handled with extreme caution. Ensuring the safety and proper handling of compressed gases is essential for preventing potentially catastrophic accidents. The Compressed Gas Association; CGA,offers a series of free safety posters to help new industry employees and end users safely interact with compressed gas products.

Download the posters above and with this information in hand, you’ll be able to create a safer work environment for your employees and prevent accidents from happening.

Throughout history, humans have used containers to store, transport, and dispense items. Regardless of the era, it is generally the case that what’s inside a container is more important than the container itself. However, when it comes to cryogens, the considerations and specifications behind their storage cylinders give these containers special notoriety.

In order to properly choose and use liquid cylinders, it is important to understand their make up as well as any considerations for their care and storage.


What are Liquid Cylinders and What are They Used For?

A liquid cylinder, sometimes called a “liquid flask” and most commonly known as a “dewar” is a double-walled, vacuum-installed container used for storing cryogens. A dewar acts like a thermos in that it keeps atmospheric gases well below ambient temperatures (sometimes as low as -400 degrees F) so that they are stored in their liquid states. 

Commonly stored cryogens include liquid nitrogen, liquid argon, liquid oxygen, and liquid helium. Depending on the design and features, dewars can dispense the elements as gas, liquid, or both. Although dewars used for temporary storage may be made out of foam insulation, most are made from metals such as aluminum or steel.

Cryogens themselves are used in many applications, such storing food, cooling superconductors, and freezing lab samples. They are also used in MRI machine functioning, producing cryogenic fields for rockets, and performing cryosurgeries. 

The benefit of dewars is that just one of them can function like many gas cylinders. This superpower is achieved by the dewar’s ability to house pressure far larger than its natural productive capacity. Because their functionalities can be equivalent to 20 high pressure cylinders, it is easy to surmise that even a single dewar can save precious storage space while significantly cutting back on costs.
​

If you’ve ever used a compressed gas cylinder, you’ve likely noticed the markings on the shoulder of the tank. Cylinders are stamped to denote the specifications of how the cylinder was made, a unique serial number, the date the cylinder was made, the owner of the cylinder, when the cylinder will need to be retested and more. We’ve made a quick guide to show you around these markings.​

1. Cylinder Specification

• The first series of letters is the specification that was used in manufacturing the cylinder itself. This is most commonly DOT–Department of Transportation, but could also be ICC for older US tanks, or CTC for Canadian tanks.
• The set of numbers specificities the type of material of construction (e.g., 3AA or 3A for steel, or 3AL for aluminum).
• Next you’ll find the rated pressure in pounds per square inch (e.g., 2,265 psi).
  
  

2. Cylinder Serial Number

3. Date of Manufacture - This date (month-year) indicates the original hydrostatic test.

4. Neck Ring Identification - Displays the name of the current owner of the cylinder.

5. Retest Markings

• The format for a retest marking is: Month-Facility-Year-Plus Rating-Star Stamp
• The + Symbol (Plus Rating) indicates the cylinder qualifies for 10% overfill.
• The ★ Symbol (Star Stamp) indicates that the cylinder meets the requirements for 10-year retest.
  
  

6. Cylinder Manufacturer’s Inspection Marking

7. Cylinder Tare (Empty) Weight

8. Gas Cylinder Label – This sticker indicates the type of gas in a cylinder, as well as its properties and hazards.
​

Cylinder Differentiation

Gas service for the cylinder can be differentiated by

1. the valve installed (which is gas specific and stamped with the CGA number) and
2. the label on the cylinder. (Label must be present or cylinder must not be used)
   
   

No compressed gas cylinder should be accepted for use that does not legibly identify its contents by name. If the labeling on a cylinder becomes unclear or an attached tag is defaced to the point the contents cannot be identified, the cylinder should be marked "contents unknown" and returned directly to the manufacturer.
​
Do not use cylinder color in order to determine cylinder content. Gas cylinders are often color coded but because the codes are not standardized between different vendors, cylinder color cannot be safely used for gas content identification. Even though medical gas cylinders do use industry standard color coding, the paint color may change over time and with weathering, so it is only safe to identify a cylinder’s contents by its label.

​​Shielding gases are used while TIG and MIG welding to protect your weld puddle from being exposed to oxygen, nitrogen, and hydrogen in the atmosphere. These elements can interact with the molten metal and cause defects in your weld. Shielding gases can also help with arc starting, cleaning, penetration, and arc stability. These gases play an important role on your finished product as well as your welding experience.

Here are important tips on keeping employees, as well as equipment, safe in the workplace.
Think safety, leave safely!
 
Potential Compressed Gas Cylinder Hazards
Compressed gas cylinders can be dangerous, and you need to be aware of the potential hazards and how to stay safe when handling, transporting, and using them.
​
The contents within the cylinder can be toxic, flammable, oxidizing, corrosive, or inert; and can cause physical harm, if not handled and stored properly. According to the Occupational Safety and Health Administration (OSHA), A compressed gas is a gas or mixture within a container. Pressure requirements have an absolute pressure of 40 psi at 70 degrees Fahrenheit or an absolute pressure of exceeding 104 psi at 130 degrees Fahrenheit, or a liquid having a vapor pressure exceeding 40 psi at 100 degrees Fahrenheit.

Here are some things to keep in mind when handling cylinders:
The cylinder can become something very similar to a missile. The valve controls the flow of gas; and if broken, you have lost the ability to manage a safe working environment. If this is not corrected, the potential mishap could be detrimental to employees and your business.
​Have you seen that MythBusters episode? (…It’s fact)  
Click here to check out their experiment.

Compressed gas cylinders can cause explosions, fires, or even deplete a working area of oxygen, if you have a faulty valve or not handling the vessel properly. Always contact your supplier whenever you have concerns about your gas cylinder!

Don’t worry, you do have control over this situation at your facility!
​
Always store cylinders upright with a chain or strap to prevent them from falling. Never store cylinders in a cabinet or closed-in area with little ventilation, this promotes a dangerous gas build up if a leak occurs.
If you store cylinders outside, you want to protect them from any extreme heat elements. When storing your cylinders inside, keep Oxygen and Nitrous Oxide at least 20 feet away from flammable gases. If you are tight on space, a high-pressure storage cabinet, with firewall, may be a good option for your company. These types of storage cabinets are engineered to be OSHA and NFPA compliant; and allow you to store oxygen and flammable gases together. Also, use the proper signage over the area where the cylinders are being stored, i.e. Flammable over the acetylene cylinders. Finally, all cylinders that are empty should be tagged and kept separate from ones that are full.

Keep the valves closed when not in use, this is especially important because some gases are inert, such as Helium and Argon (to a welding perspective). If your valve is left open, it will deplete the oxygen within your facility. It can also cause respiratory, eye, and even skin problems without the proper safety gear or plan in place. If you have a leaking valve, you will need to transport the cylinder to a well-ventilated area and call your gas supplier immediately! 

As your gas supplier (or prospective), we have included CGA Cylinder Safety Poster for download on our Resources page, check it out! 

Most accidents occur while a cylinder is being transported or moved.
Proper safety, when transporting cylinders, includes employees being fitted with safety glasses, gloves, and protective footwear. Safety wear should always be a requirement; and be worn whenever handling a cylinder. Use of a cylinder cart, with a chain or strap, instead of rolling or dragging a cylinder to the desired location, is the safest way to relocate a cylinder.  Also, make sure that the person handling the cylinder is physically capable and knowledgeable in cylinder handling. Always remember to close the valve and put the safety cap on when moving the cylinder, even if it is just a small distance away! These tips can help minimize the risks of physical injury, that can be caused by dropping or mishandling a cylinder.
When you need to transport a cylinder by vehicle, you will always want to keep the cylinders upright and strapped in securely during transport. Never ever lay a cylinder on its side, as it can lead to catastrophic damages to your vehicle and major injuries to the driver.

Safety during the use of the cylinders.
Always open the valve by hand if the cylinder is fitted with a hand wheel. If you are unable to open the valve, using a hand wheel, notify your gas supplier to request a replacement. If a tool is needed, leave it in position so the valve can be cut quickly in case of emergency. When releasing the valve, do so slowly. While in use, always keep the cylinder upright and away from sparks, high heat, fire and electrical circuit, as this will help prevent a disaster. Employees must also keep oil and grease away from oxygen cylinders, if the two mix it has the potential of violent reaction.

Even though compressed gas cylinders look sturdy, they are very dangerous! Good safety practices are vital to keeping you and your employees safe. Safety is our goal, why not take advantage of our Free Gas Application Analysis? You can click the "Learn More" button to the right of your screen and one of our gas experts will be there to assist! 
​
Here's a step-by-step tutorial on how to load your compressed gas cylinder onto a hand cart.
                              Special thanks to Matt Myers in Shipping and Receiving for the demonstration!
​

Do you think bulk gases are only for the major companies and you're too small to have a bulk tank? Maybe not. Let’s look at this topic a little closer.

​Bulk storage systems come in many different types and sizes. Bulk systems can also be tailored to fit your specific needs. The average size high pressure cylinders contain 250 standard cubic feet of gas. If you use 10, 20, 30 cylinders or more of the same gas in a month’s time, you might be a candidate for a bulk system.

Bulk systems come in several convenient sizes. They range from 40 gallons to 11,000 gallons, depending on the need. A 40-gallon tank is commonly referred to as a liquid can or dewar. They come with the same gas fitting that's on a high pressure cylinder. The liquid product in the dewar converts to 3724 standard cubic feet of product or almost 15 high pressure cylinders.

As the need increases, so can the size or number of the liquid containers. The conversion factor is 1 liquid liter of liquid Nitrogen converts to 695 liters of gaseous Nitrogen. It is common practice to take liquid Nitrogen and convert the liquid into a gas through a vaporizer, which is then used in a process. The demand of product dictates the size of the bulk system needed.

Some of the common sizes offered are:
40, 60, 250, 525, 750, 900, 1200, 1500, 3000, and up to 11,000 gallon tanks. Some systems are OK to be mounted indoors with the proper atmospheric protection, but most bulk systems are located outside and piped indoors to the related equipment. Wireless liquid level technology is available to monitor tank levels, triggering re-order of additional product to prevent service interruptions. 

​If you use 10 cylinders or more of the same gas in a month, contact us for your free evaluation. 
Learn more about the benefits of bulk gas. 

Do you need a gas regulator but aren't quite sure which type you need? This guide will outline the basic information you'll need to purchase the correct one for your application.
 
Single Stage vs. Dual Stage
Single stage regulators reduce pressure in a single step to deliver a pressure within a specific range. Regulators designed in this way will show a slight variation in delivery pressure as the cylinder pressure falls during use. For this reason, single stage regulators are best suited for applications where a constant outlet pressure is not critical, where an operator can monitor and readjust pressure, or where inlet pressure is constant. Dual stage regulators perform the same function as single stage regulators. However, delivery pressure remains constant as cylinder pressure decreases, and greater accuracy in pressure control is maintained because the pressure reduction is performed in two steps. Dual stage regulators are recommended for applications requiring a constant outlet pressure over the life of a gas cylinder.
 
Materials of Construction
The materials of construction for a regulator should be selected based on the properties and purity of the gas being used. Regulators are typically made from brass, aluminum, and 316L stainless steel. Brass is compatible with most of the non-reactive gases. A choice of forged body or barstock construction is available. Forged body regulators are economical; however, their internal surface finishes are relatively rough as compared to barstock body regulators. Barstock body regulators have all wetted surfaces machined to a smooth finish, which reduces the possibility of contamination. 316L stainless steel is highly corrosion resistant and is suitable for use with many of the highly corrosive gases in their anhydrous form. Aluminum is an economical lightweight alternative to stainless steel for many of the mildly corrosive gases. Consult Earlbeck Gases to determine suitable materials of construction.

Cylinder Connections
In the US, the Compressed Gas Association (CGA) has designated specific cylinder connections for each gas service and pressure rating. Refer to CGA publication V-1 for more information. Please note that a CGA connection limits the temperature range of a regulator to the guidelines of the connection.
Once you have determined your gas’s CGA number, you will use the corresponding CGA on your gas cylinder. CGA numbers are typically (but not always) stamped on the regulator just above the threads of the cylinder connection. Click here for our printable guide of the common outlet CGA numbers.
 
Specific Applications
While a single or dual stage regulator of the appropriate material will suffice in most gas services, some applications require specially designed regulators.  If you are unsure about your requirements, please contact Earlbeck Gases for assistance.