Steam flowmeters

An ultrasonic mass flowmeter for steam generally must achieve high accuracy, /spl sim/1% of reading or better, despite application problems such as a hot medium, very low acoustic impedance compared to liquids, usually but not always turbulent, and potentially liquid-bearing. Flow is sometimes bidirectional. Flow velocity V can range from 30 cm/s to >Mach 0.1. Solutions for measuring the flow of dry or saturated steam are presented, which have operated (a) in the USA and in Holland for three years, without maintenance and (b) in about 100 locations in an auto manufacturing plant in Japan, without a significant pressure loss in the flowcell. T/sub MAX/ was 340/spl deg/C in the work in Holland.