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Standard for Medical Gas Markers


The standards for the labeling of medical gases were established through collaboration with the National Fire Protection Association (NFPA) and The Compressed Gas Association (CGA). The purpose of the standard is to ensure uniformity for the identification and marking of medical equipment intended for use with specific medical gases.

Medical Gas Pipe Marker Placement 

  • At intervals of not more than 20 feet
  • At least once in or above every room
  • On both sides of walls or partitions penetrated by the piping
  • At least once in every story height traversed by risers

What’s new to the 2021 update to NFPA 99C/CGA C-9 Standard for Medical Gas Markers? 

The most recent update to NFPA 99C/CGA C-9 is the addition of the Medical-Surgical Vacuum/WAGD Combination legend. Per NFPA 99C/CGA C-9 "Where vacuum systems are used to serve WAGD systems in accordance with, piping in the immediate area of the WAGD system shall be labeled to indicate both systems”. Medical-Surgical/WAGD combination legend can be abbreviated to read "Med-Surg/WAGD"

What color should the new Medical-Surgical/WAGD Combination Legend be? 

One half of the legend should read "Medical-Surgical” or the abbreviated "Med-Surg" and be white with black text, while the other half should read WAGD and be purple with white text. See image the below image for an example of both a Med-Surg/WAGD label and Medical Gas Valve Tag. 


Download our NFPA 99C/CGA C-9

Medical Gas Marker Standards Chart

Gas Service Abreviated Name Colors Text/Background Standard Gauge Pressure Sample
Carbon Dioxide CO2 White/Gray or Black/Gray 50-55 psi CARBON DIOXIDE CARBON DIOXIDE
Helium   White/Brown 50-55 psi HELIUM
Instrument Air   White/Red 160-185 psi INSTRUMENT AIR
Laboratory Air   Black/Yellow & White Checkerboard None LABORATORY AIR
Laboratory Vacuum Black Box With White Text/Black
& White Checkerboard
Medical Air Med Air Black/Yellow 50-55 psi MEDICAL AIR
Medical Surgical-Vacuum Med Vac Black/White 15 in to 30 in HGV MEDICAL SURGICAL VACUUM
Nitrogen N2 White/Black 160-185 psi NITROGEN
Nitrous Oxide N2O White/Blue 50-55 psi NITROUS OXIDE
Non-Medical Air
(level 3 Gas-Powered Device)
Black/Yellow & White
Diagonal Stripe
Non-Medical Vacuum
& Level 3 Vacuum
Black Box With White Text/Black
& White Diagonal Stripe
Oxygen O2 White/Green or Green/White 50-55 psi OXYGEN OXYGEN
Oxygen/Carbon Dioxide Mixtures O2, CO2 n% (n is % of CO2) White/Green 50-55 psi OXYGEN/CARBON DIOXIDE
Waste Anesthetic Gas Disposal WAGD White/Purple Varies with system type WAGD
Other Mixtures Gas A%/Gas B% Colors as above for major gas
background/minor gas for text