### 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.

$$e = 6.1094 \exp{\frac{17.623 \cdot T_d}{T_d + 243.04}}$$

### Cylindrical Volume Calculator

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

$$V = \pi r^2 \cdot L$$

### Tank Dilution Calculator

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

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

### 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.