Utah Atmospheric Trace gas & Air Quality Lab

This site houses technical utilities for the University of Utah’s Atmospheric Trace gas & Air Quality Lab (UATAQ). If you’re interested in publically accessible data, visit air.utah.edu.

This site is still under active development. Feedback is welcome and can be sent to Ben Fasoli.

Tank Spike Calculation

Estimate the required spike pressure when filling tanks. Ambient concentration is filled with most recent WBB observation within the last hour.



Dewpoint to Mole Fraction Converter

Applies the August-Roche-Magnus approximation of the Clausius-Clapeyron equation to estimate the mole fraction of water vapor using dewpoint temperature and ambient atmospheric pressure.

$$e = 6.1094 \exp{\frac{17.623 \cdot T_d}{T_d + 243.04}}$$
Td : Dewpoint temperature
P : Ambient pressure


Cylindrical Volume Calculator

Calculate the volume of a cylinder given the length and diameter.

$$V = \pi r^2 \cdot L$$
D : Inner diameter of tubing
L : Length of tubing


Tank Dilution Calculator

Calculate mole fraction given a tank of known concentration, a zero air dilution and two flow rates.

$$ppm = S \frac{S_{flow}}{S_{flow} + D_{flow}}$$


MiniVol Rotameter Setpoint Calculator

T : Average temperature
P : Average ambient pressure


Site checklist

Update reference tank pressures and locations.

Current tanks

Site notes (displayed in local time)

Filling of compressed gas cylinders

  • An online form must be submitted with your request and mole fraction per tank request.
  • CO2 tanks can be filled and calibrated in the range of 300 to 800 ppm.
  • The number of cylinders requested must be equivalent to those returned empty.
  • The target CO2 is usually within 5 umol/mol near ambient concentration. Values will vary at either end of the range as well as with the addition of another gas like methane.
  • Turnaround time for CO2 cylinder fills and calibration is 4 to 6 weeks. Cylinders with CO2 and CH4 may require additional time for filling and calibration. Please consider this lead-time when making request for tank fills.
  • Questions can be sent to Maria Garcia.

Compressed cylinder fill request


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