Blending Trimix by adding pure Helium and Oxygen and topping with air provides great flexibility in what final mixes you can make. This calculator allows you to take advantage of banked mixes to top with as well. Using a banked mix might reduce the amount of pure O2 or even pure He you need to add in the earlier stages.
You can fill a cylinder that has an existing volume of gas by entering the starting mix and starting pressure. Remember to analyze the tank for both O2 and He prior to using this approach if you can not otherwise be sure of it’s exact contents.
The target pressure after adding the He, O2 and topping mix is shown so that you know your target cylinder's required pressure at each step of the filling process. You can also easily change the fill order to match your situation. The target pressures are “ideal gas law” values so you can account for He compressibility in the way that you find works best for you.
Tap on the bookmark icon to recall a previously saved calculation or to save this calculation for future use.
You can easily make the calculations using Metric or Imperial/US by selecting the “Settings” tab (if it is not visible on the current screen select “More”) and changing the system to the one desired.
