▁inject ed ▁inside ▁the ▁product ▁while ▁the ▁product ▁itself ▁is ▁en closed ▁in ▁a ▁vac u um ▁chamber ▁connected ▁to ▁the ▁instrument . ▁In ▁this ▁case , ▁burst ▁and ▁leak age ▁tests ▁can ▁be ▁combined ▁in ▁one ▁operation . ▁ ▁H ydro gen ▁sensor ▁test ▁ ▁During ▁the ▁hydro gen ▁sensor ▁test , ▁the ▁object ▁is ▁filled ▁with ▁a ▁mixture ▁of ▁▁ 5 % ▁hydro gen / ▁ 9 5 % ▁nit ro gen , ▁( below ▁ 5 . 7 % ▁hydro gen ) ▁is ▁non - fl amm able ▁( ISO - 1 0 1 5 6 ). ▁This ▁is ▁called ▁typically ▁a ▁sn iff ing ▁test . ▁The ▁hand pro be ▁connected ▁to ▁the ▁micro elect ron ic ▁hydro gen ▁sens ors ▁is ▁used ▁to ▁check ▁the ▁object . ▁An ▁aud ios ign al ▁increases ▁in ▁proxim ity ▁of ▁a ▁leak . ▁D ete ction ▁of ▁le aks ▁go ▁down ▁to ▁ 5 x 1 0 − 7 ▁cub ic ▁cent im eters ▁per ▁second . ▁Comp ared ▁to ▁the ▁hel ium ▁test , ▁hydro gen ▁is ▁che aper ▁than ▁hel ium , ▁no ▁need ▁for ▁a ▁vac u um , ▁the ▁instrument ▁could ▁be ▁che aper ▁but ▁is ▁not ▁as ▁sensitive ▁as ▁a ▁hel ium ▁leak ▁det ector ▁so ▁will ▁not ▁find ▁smaller ▁le aks . ▁ ▁Chem o - chrom ic ▁hydro gen ▁leak ▁detect ors ▁are ▁materials ▁that ▁can ▁be ▁pro act ively ▁applied ▁to ▁a ▁connection ▁or ▁fitting . ▁In ▁the ▁event ▁of ▁a ▁hydro gen