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Octafluorocyclobutane is a colorless, odorless, non-flammable liquefied gas. It is shipped as a liquefied gas under its own vapor pressure.

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Formula: C4F8, R318, HC-318

What is Octafluorocyclobutane Gas?

Octafluorocyclobutane is a colorless, odorless, non-flammable liquefied gas. It is shipped as a liquefied gas under its own vapor pressure (25 psig @ 70º F). C4F8, also identified as Refrigerant-C318, is used in some specialty refrigeration applications.

Common Uses of Octafluorocyclobutane Gas

Octafluorocyclobutane can be used as an extinguishing agent in fire suppression systems. This is due to the large total heat absorbed in going from the fluid at room temperature up to a temperature of 1400 K. 

Also, C4F8 is used in the semiconductor industry for plasma etching.  In the RF field, C4F8 generates reactive species that selectively etch silicon. In the etching process, the C4F8 plasma free radicals can form a protective polymer that blocks chemical attacks on features and can provide sidewall protection.

We offer Octafluorocyclobutane gas in a variety of purities and concentrations. See the chart below and download the spec sheets and safety data sheets for more information on purchasing C4F8 tanks and cylinders from EFC.




Further Specifications

Cylinder Sizes

  • Plasma Etching
  • Making other chemicals
  • Refrigerant (in specialized applications)
  • "Modify" the properties of homofluoropolymers
  • Production and processing of semiconductor materials and devices
  • Deposition gas
  • Replacement of Ozone for depleting chlorofluorocarbon refrigerants
  • Extinguishing agent in fire suppression systems
Grade 3 Grade 3.8 Grade 4.5 Grade 5
Purity 99.9% 99.98% 99.995% 99.999%
Nitrogen < 80 ppmv < 8 ppmv < 3 ppmv
Oxygen < 20 ppmv < 2 ppmv < 1 ppmv
Air (N2+O2+CO+CO2) < 300 ppmv
Moisture < 10 ppmv < 10 ppmw < 3 ppmw < 1 ppmw
Tetrafluorocarbons < 50 ppmv
Other Fluorocarbons < 50 ppmv < 10 ppmv < 4 ppmv
Other Organics < 1000 ppmv
Acidity < 0.1 ppmv/w < 0.1 ppmv/w < 0.1 ppmv/w
Chemical & Physical Properties
Molecular Weight 200.03
Specific Volume 1.85 cu.ft/lb
Pressure @ 70º F 23.5 psig
Valve Outlet CGA 660 DISS 716
Shipping Data
DOT Name Octafluorocyclobutane
Hazard Class 2.2
DOT No. UN 1976
DOT Label Green, Non-flammable gas
CAS No. 115-25-3
Cylinder Size Fill Weight (lb)
49L/Size 300 118
44L/Size 200 100
16L/Size 80 35
7L/Size 35 15

FAQs about Octafluorocyclobutane

How do you handle Octafluorocyclobutane gas safely?

We recommend handling Octafluorocyclobutane in a well-ventilated place while wearing suitable protective clothing. Make sure to avoid contact with skin and eyes and avoid the formation of dust and aerosols. Also, it’s important to use non-sparking tools and prevent fire caused by electrostatic discharge steam.  

Before Use: Move cylinders with a suitable hand truck. Do not drag, slide, drop or roll Octafluorocyclobutane cylinders and secure them firmly. Leave the valve protection cap in place (if provided) until the cylinder is ready for use.

During Use: Use designated CGA fittings and other support equipment. Do not use adapters. Do not heat the cylinder by any means to increase the discharge rate of the product from the cylinder. Use a check valve or trap in the discharge line to prevent hazardous backflow into the cylinder. Do not use oils or grease on gas-handling fittings or equipment.

After Use: Close the main cylinder valve. Replace valve protection cap (if provided), then mark empty cylinders “EMPTY.”

How should you store octafluorocyclobutane cylinders?

Octafluorocyclobutane cylinders should be stored in dry, well-ventilated areas away from heat sources. Compressed gases can present significant safety hazards. Store containers away from heavily trafficked areas and emergency exits. Store the container tightly closed in a dry, cool, and well-ventilated place. Store apart from foodstuff containers or incompatible materials.

How is octafluorocyclobutane used in fire suppression?

Octafluorocyclobutane is ideal for fire suppression because it is non-flammable. The gas is stored in liquid form for the fire suppression system and, when released, it physically changes to a gas, a process during which heat is absorbed and flame can be extinguished.

How is octafluorocyclobutane used in plasma etching?

The plasma etching process utilizes a high-speed stream of plasma comprised of a gas mixture and shoots it in pulses at the circuit or chip. The plasma creates a volatile chemical reaction, during which the atoms of the plasma embed themselves at the surface of the circuit or chip, which modifies its physical properties, which is etching. Octafluorocyclobutane is an ideal gas for the plasma mixture because it chemically combines with the other gases, is non-flammable, and produces the proper volatile chemical reaction. 

What industries is octafluorocyclobutane used in?

In addition to fire suppression systems and plasma etching, octafluorocyclobutane is used as a gas in refrigeration systems, and in some aerosolized food products, as it is non-toxic, non-flammable, and chemically inert. 

**Moisture level guaranteed only when Electronic Fluorocarbons prepares the cylinders.
All concentrations are on a mol/mol basis unless otherwise stated.
Product sold on the basis of total impurities. Individual impurities may vary slightly.

*This gas not available for purchase online.