Gas-flow Silencers Or Exhaust Apparatus For Machines Or Engines In General; Gas-flow Silencers Or Exhaust Apparatus For Internal Combustion Engines
C04B
Lime, Magnesia; Slag; Cements; Compositions Thereof, E.g. Mortars, Concrete Or Like Building Materials; Artificial Stone ; Ceramics ; Refractories; Treatment Of Natural Stone
B01J
Chemical Or Physical Processes, E.g. Catalysis Or Colloid Chemistry; Their Relevant Apparatus
G01N
Investigating Or Analysing Materials By Determining Their Chemical Or Physical Properties
