Hydrogen gas has a number of unique properties which make it an excellent
trace gas for use in leak detection and testing:

• The lightest of all molecules
• Lowest viscosity of all gases (easy to fill, evacuate and dissipate)
• Low background (0.5 ppm)
• Environmentally friendly and renewable
• Inexpensive
• Non flammable (when diluted 5% in Nitrogen)
• Non toxic - non corrosive

Pure hydrogen should never be used as trace gas. We recommend a standard industrial grade mix of 5%hydrogen in nitrogen. This mix is inexpensive, non- flammable, easily available and still holds the important features needed for using hydrogen as trace gas. Below you will find some facts about hydrogen and diluted hydrogen as trace gas.

• Hydrogen gas has the lowest viscosity, mainly because the Hydrogen
molecule only weighs half as much as a single Helium atom.
• Hydrogen spreads quicker in a given volume because of its high molecular velocity
• It finds and passes through a leak faster
• It is easier to flush out and vent away
• Hydrogen molecules do not stick to surfaces as easily as Helium atoms.
That is why you get less problems with background interference from gross
leaks and residual gas in tested objects.

The Hydrogen Method...

• can locate leaks
• is independent of variations in temperature
• is perfect for testing soft objects
• is independent of size of test objects’ internal volume
• has a high sensitivity (Pressure Decay from 10E-2 ml/s, Hydrogen Method
from 5x10E-7 ml/s)

more info...