A small flow sensor for flowrates up to 1 L/min
The SLF3S-4000B liquid flow sensor (photo) accurately measures flowrates up to 1 L/min with the usual quality, while measuring just 5 cm in length and weighing 7 g. Normally, either higher flow velocities or larger channel cross-sections are required to accurately measure high flowrates; both factors, however, increase the likelihood of turbulence. To overcome this hydrodynamic limitation, this company employs a design trick — the new channel profile has a W shape. This allows the micro-electromechanical system (MEMS) chip to be positioned along the narrower side stream (with laminar flow), where it can really demonstrate its measurement performance. The new sensor covers flowrates from microliters per minute to 1 L/min. Initial field trials are also being planned for a device handling flowrates up to 20 L/min. — Sensirion AG, Stäfa, Switzerland