Purchases of GML reference gas preparation and calibration services can only be initiated through a project contract.
Here is an example Memorandum of Understanding [MOU] Contract. Prices for the services are listed in the MOU.

For more information on calibration services, contact refgas@noaa.gov

Purchase and Filling of Compressed Gas Cylinders

The cost of a standard varies with the cylinder type and level of complexity. Cylinders are filled with natural air from Niwot Ridge, Colorado.

  • CO2 can be adjusted and calibrated between 250 and 3000 μmol/mol. The target CO2 value is usually within 5 μmol/mol for near ambient concentrations. Increasing the amount of CO2 over ambient levels requires adding CO2 which is isotopically lighter than ambient. The closer to ambient CO2 levels we target, the closer the air will be in regards to the stable isotopes of CO2. Lower than ambient standards usually have very close to ambient stable isotopes of CO2.
  • CH4, CO and N2O can be adjusted but with greater targeting variability.
  • Halocarbon concentrations can sometimes be adjusted to user requirements on an individual basis (contact Brad Hall for information).
  • Cylinder valve connection is CGA-590.
  • A standard gas cylinder requires 4-6 weeks to fill and 3 weeks for each trace gas species to calibrate. The normal turn-around time varies due to seasonal logistics and calibration queue
  • Note that for filling tanks to be used for halocompound reference gases, a different Rix compressor is used than for the filling of cylinders for CO2/CH4/CO/N2O, SF6. This compressor has been modified to reduce contaminants that can interfere with gas chromatography with electron capture detection.

Cylinder Types

Different types of cylinders are used depending on the molecule of interest.

  • Cylinders for CO2/CH4/CO/N2O/SF6 are bare aluminum N30, N60, N80, N150, N265 Luxfer (or equivalent) cylinders. The most common size we use is N150, 29.5 liter internal volume, pressurized to 130 bar, containing approximately 4000 liters of air. Cylinder valves are Ceodeux, brass packles, CGA590 port connection.
  • The majority of halocompound standards are prepared in Aculife-treated aluminum cylinders (size AL-150) purchased from Airgas.
You can also read a description about how standard reference gases are filled.

Calibrations of Compressed Gas Cylinders

NOAA GML is the World Meteorological Organization (WMO), Global Atmosphere Watch (GAW) Central Calibration Laboratory (CCL) for CO2, CH4, N2O, SF6, and CO. Calibrations results for these species are on official WMO scales. Calibrations for other gases are on internal NOAA scales.

Calibrations can be performed on the stable isotopes of CO2 (C13 and O18). The CO2 stable isotope calibration is based on a provisional scale maintained by INSTAAR at the University of Colorado. Values given for the stable isotopes of CO2 are informational values only.

One recalibration for CO2, CH4 or CO after use is included in the cost of the standard gas. This is HIGHLY RECOMMENDED every 3 years for precision work and should at least be performed at the end of the cylinder's use (20 atm pressure).

Pre-purchase Quotes

For more information and pre-purchase quotes, e-mail refgas@noaa.gov. A quote is necessary before accepting a purchase order. Inquiries can also be made through the following address, fax, or phone:

National Oceanic and Atmospheric Administration
Global Monitoring Laboratory
325 Broadway
Boulder, CO. 80305
E-Mail refgas@noaa.gov
Fax 303-497-6290