These instruments are designed for use in chemical and petrochemical processing industries, and in conventional power plants, to measure gaseous or liquid media which do not have high viscosity or do not cristalize. They are built to resist the most severe operating conditions created by the ambient environment and the process medium. For use on power units, pumps, hydro-cleaning machines, presses, engine compressors, turbines, diesel engines, chemical, petrochemical and refrigerating plants and on machines and equipment where pulsating pressures or mechanical vibrations are apparent, the liquid-filled version is recommended.