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Gas Flow Calibrations
18010C

NIST provides calibration services for gas flow meters using three pressure, volume, temperature, and time (PVTt) systems with collection tanks of 34 L, 677 L, and 26 m3. These primary standards cover flow ranges of (1) 0.03 L/min to 100 L/min, (2) 10 L/min to 2000 L/min, and (3) 200 L/min to 78,000 L/min respectively. The 34 L PVTt can calibrate flowmeters in any non-corrosive and non-hazardous gas that is available in pressurized cylinders, including nitrogen, argon, argon, helium, etc. The uncertainty of the 34 L and 677 L PVTt standards is between 0.02% and 0.05%, depending on the gas and flow that is tested. The 26 m3 standard has flow uncertainty of 0.13%.

The PVTt systems are best suited for calibrating critical flow venturis or critical nozzles since pressure at the inlet of the standard varies between vacuum and 100 kPa as the collection tank fills. The Working Gas Flow Standard (WGFS) is normally used for other flowmeter types, e.g. laminar flow elements, turbine meters, and positive displacement meters. The WGFS uses critical venturis and critical nozzles that have been calibrated in the PVTt standards as working standards or reference flowmeters to calibrate other flow devices. The uncertainty of the WGFS ranges from 0.1% to 0.3% depending on the flow being calibrated.

To read more about the principles of operation and uncertainties of our gas flow standards and see sample calibration reports, see our Technical Notes and Publications.

Fittings available include national pipe thread (NPT), Swagelok™, VCR, VCR, AN 37 degree flare, ASA 150 lb, ASA 300 lb, and ASA 600 lb and pipe diameters range from 3 mm to 203 mm.

A typical calibration costs $4500. We deliver a calibration report that includes an uncertainty analysis for the flowmeter calibration factor. This uncertainty included the uncertainty of the flow standards given above as well as uncertainties related to instrumentation associated with the meter under test and its reproducibility. A normal flow calibration includes five flow set points, with three or more averages of the meter readings and the flow standard made at each flow, with this entire sequence repeated on a second occasion to assess reproducibility. It is helpful if the customer specifies the flow set points and the instrumentation requirements of the meter (pressure, temperature, full scales required).

Turnaround time for a single flow meter is approximately 4 weeks:

  1. Allow 2 weeks for shipping;
  2. 1 week for report writing and review; and
  3. 1 week for set-up and data collection.
Please contact Gina Kline  to schedule the calibration of your instrument(s).

To have your gas flow meter(s) calibrated:

  1. Contact Gina Kline to schedule your calibration dates;
  2. fax or mail a purchase order to Gina Kline following purchase order guidelines and choosing a Service ID Number which can be found in the NIST Calibrations User’s Guide SP 250, and
  3. ship your flow meter(s) to Gina Kline following shipping procedures outlined in the "NIST Calibrations User’s Guide SP 250."
Gina Kline
National Institute of Standards and Technology
Fluid Flow Group
100 Bureau Drive, Stop 8361
Gaithersburg, MD  20899-8361
Phone:  301-975-4813
Fax:  301-258-9201
Email:  gkline@nist.gov


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