tracer gas basic knowledge
Please use 5% H2 mix with 95% N2 exclusively.
Smartly trap escaping hydrogen gas in the field ,
460 model Bell probe is a good solution, for example,or similar.
Gas reaction have response time which is slower than huiman touch hot surface, especially when in low hydrogen concentration point and you get 0.0 ppm reading, you need wait at that point more than 5 seconds, in case use Variotec 460 instrument.