GasTag for iOS
- View live gas readings from your DiveSoft Analyzer and print professional tank labels wirelessly
- Save a history of your analyzed tanks directly on your iPhone
Requires iOS 17.0 or later. Compatible with iPhone.
App Features
Everything you need for efficient gas analysis
Live Gas Readings
See Helium, Oxygen, temperature, and pressure in real-time as you analyze.
MOD Calculation
Automatic Maximum Operating Depth calculation at user selectable PPO₂, for fresh or salt water.
Gas Density Limit
Optionally print the depth where your mix reaches your preferred gas density (5.2 g/L by default).
Equivalent Narcotic Depth
Optionally print the END of your mix, with a setting for whether O₂ counts as narcotic.
Label Preview
See exactly what your printed label will look like before printing, with the option to include a narrow label with just the analysis for placing on top of the valve.
One-Tap Printing
Print professional, color tank labels wirelessly to your Brother printer.
Label Sharing
No printer? No Problem! You can still save history of your analysis in the app log or save an image to your files.
Mix Notation
Standard gas mix notation (e.g., 16/40) calculated automatically.
Analysis History
Review past readings and reprint labels when needed.
Gas Density & END on Your Labels
Plan trimix dives with the limits that matter printed right on the tank
Turn on Show Max Depth and Show END in Settings to add a row under the MOD on every label.
- MAX @ g/L is the depth where the mix reaches your preferred gas density. The default is 5.2 g/L, the commonly recommended limit; 6.2 g/L is the usual maximum.
- END is the Equivalent Narcotic Depth at the shallower of the MOD and the density limit, so it is never shown for a depth the gas can't be used at. O₂ is counted as narcotic by default, and you can switch to nitrogen only.
- Fresh or salt water. Depths for MOD, density and END follow your water setting. Salt water uses the EN 13319 standard of 10 m of seawater per bar; fresh water uses a density of 1000 kg/m³.
Depth limits are rounded down and END is rounded up, so the label always errs on the conservative side. Always verify your gas and follow your training.
Printer Setup
Connect your Brother QL-820NWB for label printing
Required Printer
GasTag works with the Brother QL-820NWB label printer using DK-2251 continuous length labels (red/black on white) or for longer lasting labels in the water we recommend DK-2212 continuous length labels (black and white only). The DK2251's will last for a few dives but are available in red/black on white while the DK-2212's last longer, they are great for stage or bailout bottles but only available in black and white.
Pairing Steps
- 1 Turn on your Brother QL-820NWB printer
- 2 On the printer, hold the Bluetooth button until the light blinks
- 3 On your iPhone, go to Settings → Bluetooth
- 4 Find and pair with "QL-820NWB"
- 5 Open the GasTag app and tap the printer icon to connect
Compatibility
iPhone 15 or later
USB-C port can power the GasTag bridge directly. Connect your iPhone to the ESP32 with a USB-C cable.
Older iPhones
Use a USB power bank to power the GasTag bridge. The app connects via Bluetooth regardless of how the bridge is powered.