Flow measurement in gas drainage

This paper reviews the need for flow monitoring in gas drainage and the flowmeters that are available to do this. As suitable flowmeters that are capable of dealing with gas, water and particulate matter do not exist work has been done to adapt ball valves for this purpose. They have been found to fill the function admirably and with a combined manometer and pressure sensor can provide flow ranges in excess of 100:1. They can also be left wide open to avoid blockage when not being used for measurement.