Glass tube variable area meters give the most cost-effective method of accurate fluid flow measurement in both gases and liquids.
Now Influx Measurements, of Duff & MacIntoshP/L has taken this technique further by monitoring the float position in the glass tube using a field sensor.
The new Reflux two wire 4-20mA loop powered output allows remote transmission and recording of the flow rate, plus a totaliser option, and also brings the advantages and low cost of variable area technology into modern electronic control systems.
Frequently used in laboratories, and for monitoring cooling and purge gas flows, Reflux flowmeters are available for flowrates of air (FSD at ATP) from 3.5 to 2000l/min, and water from 0.5 to 100l/min.
Calibration for other process fluids and conditions are available, as are specific models for OEMs.
The operational turndown is typically 10:1, for an analogue output accuracy of 2%.
The loop-powered transmitter is also available with EEXia certification for use in hazardous areas, and is supplied with the glass tube in safety housing suitable for use on process pressures up to 20bar.
The float is still visible through the window in the Reflux housing, retaining the normal flow indication often preferred by operators on site.
Metal tubed flowmeters are also available for higher temperatures and pressures, with external scales to indicate flow rate.
Influx manufactures a range of flow measurement systems, many based on the variable area meter concept, with both glass, plastic and metal flow tubes.
Simple visual flow indicator units are also supplied, as well as units with high or low flow alarm trips.