If you've seen a pictogram showing a gas cylinder on a chemical label or safety data sheet, you've encountered the gas under pressure symbol, one of nine standardized hazard pictograms used across GHS, OSHA, and WHMIS systems. It looks simple enough, but the hazards it represents are anything but. Compressed gases, liquefied gases, dissolved gases, and refrigerated liquefied gases each carry distinct risks, from explosive rupture to severe cold burns, and misidentifying them can have real consequences on the job.
At Safety Decals, we help businesses get safety labeling right, from custom hazard decals to regulatory compliance support. Proper hazard communication starts with understanding what each symbol actually means and when it applies. That's exactly what this article covers: the gas under pressure pictogram, the specific gas categories it represents, and how GHS, OSHA, and WHMIS each use it to keep workers informed and protected.
Why the gas under pressure symbol matters
The gas under pressure symbol isn't just a label requirement you check off a compliance list. It's a front-line communication tool that tells workers, emergency responders, and handlers exactly what kind of hazard they're dealing with before anyone opens a valve or moves a cylinder. When this pictogram appears on a container, it signals that the contents are stored under significant mechanical pressure, and a failure in containment, even a minor one, can cause serious injury or death.
Regulatory requirements under GHS, OSHA, and WHMIS
Across GHS-aligned frameworks, OSHA's Hazard Communication Standard (HazCom 2012) requires chemical manufacturers and importers to classify gases under pressure and place the correct pictogram on labels and safety data sheets (SDS). In Canada, WHMIS 2015 adopted the same GHS-based pictogram system, making the gas cylinder symbol a recognized requirement on both sides of the border. If your business handles, stores, or ships compressed gases, you're legally required to display this symbol correctly on every container that falls under these categories.
Failing to label compressed gas containers correctly under OSHA HazCom rules can result in citations, fines, and increased liability if a workplace incident occurs.
What's actually at stake for workers
Workers who don't recognize this symbol, or don't understand what it covers, face higher risk of mishandling containers in ways that appear routine but carry real consequences. A refrigerated liquefied gas cylinder, for example, looks nearly identical to a standard compressed gas cylinder, but the cold burn hazard from liquid nitrogen or liquid oxygen escaping under pressure is severe and immediate. Knowing the symbol means understanding the specific gas category on the label, and that distinction drives better decisions about storage conditions, transport procedures, and PPE requirements.
Beyond individual safety, your organization's overall hazard communication program depends on workers recognizing and responding to each pictogram correctly. Consistent, accurate labeling is what connects regulatory compliance to actual on-the-floor behavior where it matters most.
What the symbol looks like and where you see it
The gas under pressure symbol features a black gas cylinder silhouette centered inside a white square set on a red diamond border. This design follows the GHS pictogram format, which standardizes hazard symbols so workers recognize them instantly regardless of language or industry. The image is clean and direct: a single upright cylinder with a valve on top, no additional elements.
The visual design of the pictogram
You'll notice the cylinder icon looks deliberately straightforward. No flames, no skull - just the cylinder itself, which communicates physical pressure hazard rather than chemical toxicity or flammability. In black-and-white print (such as on some SDS documents), the red border appears as a black diamond outline, but the cylinder image stays the same. This consistency is intentional so the symbol remains immediately recognizable across formats and printing conditions.
The red diamond border is a required part of the GHS pictogram format and cannot be substituted or omitted on compliant labels.
Where you'll find it on labels and documents
This pictogram appears on the physical product label of any container holding a gas under pressure, including portable cylinders, aerosol cans, and bulk tanks. You'll also find it in Section 2 of the Safety Data Sheet, where all applicable hazard pictograms are listed alongside signal words and hazard statements. Warehouses, transport vehicles, and any storage area holding compressed gas containers should display it clearly on each individual container.
What hazards it covers in GHS, OSHA, and WHMIS
The gas under pressure symbol covers four distinct gas categories under GHS, OSHA HazCom, and WHMIS 2015. Each category carries different physical hazards, so understanding which one applies to your container directly affects how you store, handle, and respond to incidents.
The four gas categories it identifies
GHS classifies gases under pressure into four specific categories, each with its own hazard statement printed on the label and listed in Section 2 of the SDS:
- Compressed gas: Stored entirely in gas phase at -50°C or above under high pressure.
- Liquefied gas: Partially liquid at packaging temperature due to high internal pressure.
- Refrigerated liquefied gas: Kept liquid by low temperature rather than pressure, posing serious cryogenic burn risks.
- Dissolved gas: Dissolved in a liquid solvent under pressure, such as acetylene stored in acetone.
Signal words and hazard statements
Each category uses "Warning" as the signal word rather than "Danger," which places these hazards at a serious but not maximum severity level. The hazard statements differ by type: compressed gases carry "Contains gas under pressure; may explode if heated," while refrigerated liquefied gases add warnings about cryogenic burns and frostbite from liquid release.
Reading the specific hazard statement on your label tells you whether your primary risk is heat-driven explosion, cold burns from escaping liquid, or pressure buildup from a dissolved gas.
How to handle and store gases under pressure safely
When you see the gas under pressure symbol on a container, it tells you to apply specific precautions before you move or store it. Improper handling of pressurized containers is one of the leading causes of preventable workplace injuries involving gases, and following the right practices cuts that risk significantly.
Storage conditions that reduce risk
Store all gas cylinders upright and secured to a wall or fixed structure using chains or brackets to prevent tipping. Keep cylinders away from heat sources, open flames, and direct sunlight, since rising temperatures increase internal pressure in both compressed and liquefied gas containers.
Refrigerated liquefied gas containers have specific temperature requirements that differ from standard compressed gas storage; always check the SDS before choosing a storage location.
Separate full and empty cylinders and store incompatible gases, such as oxidizers and flammables, in distinct, ventilated areas clearly marked for each gas type.
Safe handling practices for pressurized containers
When moving cylinders, always use a hand truck or cylinder cart designed for that purpose. Never drag, roll, or drop a cylinder, and always replace the valve protection cap when the container is not connected to equipment. Check your valve and regulator connections for leaks before putting any cylinder into service, using an approved leak detection solution rather than an open flame.
Train all workers who handle these containers on the specific hazard category listed on each label and the correct PPE requirements for each gas type before they start work.
Common examples and related pictograms
The gas under pressure symbol appears on a wide range of containers you encounter across industrial, medical, and commercial settings. Understanding which specific gases trigger this pictogram helps you apply the right handling procedures without having to pull up an SDS every time you see a new container on the floor.
Common gases that carry this pictogram
Propane, compressed air, and nitrogen are among the most frequently handled compressed gases that display this symbol in manufacturing and construction environments. Liquid nitrogen and liquid oxygen fall under the refrigerated liquefied gas category, making them standard in medical facilities and laboratories. Acetylene, used widely in welding operations, qualifies as a dissolved gas stored in acetone under pressure and carries the same pictogram on every cylinder.
Aerosol cans, including common workshop spray lubricants and refrigerants, also fall under the gases under pressure classification and must display this pictogram on their product labels.
Related GHS pictograms you should recognize
Several other GHS pictograms often appear alongside the gas under pressure symbol on the same label, depending on the specific gas involved. Flammable gases like propane and hydrogen also display the flame pictogram, signaling a combined physical and fire hazard. Oxidizing gases such as oxygen carry the flame-over-circle pictogram instead. Recognizing these combinations gives you a complete picture of every hazard on a container before you handle it, rather than acting on a single symbol alone.
Conclusion
The gas under pressure symbol tells you more than just "handle with care." It identifies a specific category of physical hazard, whether that's a compressed gas that can rupture under heat, a refrigerated liquefied gas that causes cryogenic burns, or a dissolved gas like acetylene stored under pressure. Understanding each category and the hazard statements that go with it is what separates basic regulatory compliance from a safety program that actually protects people on the floor every day.
Accurate, durable, and visible labeling is the foundation of that program. Every container your workers interact with needs a label they can read and act on quickly, without needing to cross-reference a document first. Whether you need custom compressed gas labels, replacement cylinder decals, or support building a complete hazard communication system, Safety Decals has the materials and expertise to deliver. Get the right safety decals for your compressed gas containers and make sure your team can identify every hazard before it becomes an incident.
