precision measuring apparatus, namely apparatus for measuring physical properties of gases and liquids; air analysis apparatus; gas testing instruments; measuring instruments, namely, instruments for measuring physical properties of gases and liquids; electric monitoring apparatus, namely, electronic, optical, thermal, accoustic and chemical sensors for measuring physical properties of gases and liquids measuring instruments, namely, gasometers; aerometers; testing apparatus not for medical purposes, namely, apparatus for testing physical properties of gases and liquids including respiratory gases, process feed-stock gas and liquids, in process gas and liquid sampling, inerting/combustion control process gases, infrared detectors; downloadable electronic publications in the nature of application notes, technical bulletins, operation manuals, service manuals in the field of measuring physical properties of gases and liquids