A control circuit (20) of a mass flow control device (1) retains the relation (Cd=f(ReTH)) between the Reynolds number and the actual discharge coefficient of a sonic nozzle (13) in the area where the Reynolds number is small. In such an area, the sonic nozzle can be used as a variable mass flow element...http://www.google.es/patents/US6012474?utm_source=gb-gplus-sharePatente US6012474 - Mass flow control method and device utilizing a sonic nozzle
Mass flow control method and device utilizing a sonic nozzle
