Products featured include the FMG600 Series of electromagnetic flowmeters,the FDT-40E Series of clamp-on ultrasonic energy flowmeters, and the FMA-LP2600A low pressure drop gas mass flow controllers for clean gases.

In addition, there is an article called Applying ultrasonic level sensors in ultrapure water tanks: https://www.omega.co.uk/about/register/UK_Flow_Register.html

https://www.omega.com/technical-learning/ultrasonic-level-sensors-in-ultrapure-water-tanks.html