portable gas detector 1.detect various of toxic gases ... made. 1.We are one of the leading gas detecting tube and instruments supplier in China mainland. ... China. 2.Our company specializes in producing colorimetric gas detection tube. All kinds of tubes have been ... Ammonia, Hydrogen Sulfide, Nitrogen Dioxide, Sulfur Dioxide, Chlorine, Benzene, Toluene, Xylene, Hydrogen, Ethylene, Phosphine etc. They can ...