The Pro series is suitable for liquids and most gases. They take weight measurements immediately (mass). If you want to measure volume, you’ll need to do a density correction at fluid base conditions. The majority of meter devices combine mass rate and density for liquids into one instrument. Because these meters react to mass, they may be used to measure some liquid and gas mixes (within limitations). They do not correctly measure gas density. Because such an application poses unique challenges, the manufacturer should be contacted for recommendations on a meter’s limitations with mixes. To reduce difficulties with hostile fluids, special building materials are given.