We have been specifying thermal mass flowmeters for 21+ years and Eldridge Products gives you innovative, high-performance gas flowmeters for gas mass flow measurement.  EPI was the originator of the first thermal mass flow meter to utilize patented  thermal Flow Averaging Tubes (FAT™) and introduced the first all microcontroller operated flow sensor design.  In addition to developing a high temperature stack flow meter capable of reaching temperatures of 900 F, EPI introduced the Epi-Val™ with LiveZero™ In-Situ or field validation Field-Val™ firmware with EPICom interface for the Master-Touch™ & ValuMass™ lines of flow ,metering solutions. The high contrast graphical display provides you flow rate, temperature, total flow and diagnostic information. The digitally-driven circuit eliminates the traditional drift-prone analog Wheatstone bridge, improving your stability, eliminating long term drift and provides a reproducible zero flow data point.  This enables you to perform a simple single-point in-situ calibration verification traceable back to the original NIST calibration certificate.  You can perform this check while the process is running with the EPI-Val™ with LiveZero™ , downloading the results into a PDF format.