I need to detect the flow of water inside a pipe, as sensitively as possible. I initially considered either a small turbine or a paddle wheel, with magnets attached so that a hall sensor could detect their rotation. But I'd like the device to be long lived, and a rotating shaft might wear its bushings prematurely. I only need to detect the presence of flow. Precision measurement is not necessary.
The pipe I'm using is 1-1/4" Schedule #40 PVC. A reasonable lower limit for flow detection would be 0.1 lt/min. That would yield a flow linear speed of approximately 1 mm/sec.
If I were to use a turbine, then a small jewel acting as a bearing would be needed at the downstream end of its shaft, and that's a little too complicated for what I want. And if I were to use a paddle wheel, the device would be limited in that the pipe would have to be installed in such way that the wheel's shaft would have to be horizontal, otherwise the wheel would lean its weight on one of its sides and grind against the bushing.
I own a 3D printer, so fabricating a complex part in ABS is not a problem for me.
A sort of astable vibrating mechanism... something like a wiggling snake comes to mind. But I haven't seen anything like it out there ... any thoughts?
The pipe I'm using is 1-1/4" Schedule #40 PVC. A reasonable lower limit for flow detection would be 0.1 lt/min. That would yield a flow linear speed of approximately 1 mm/sec.
If I were to use a turbine, then a small jewel acting as a bearing would be needed at the downstream end of its shaft, and that's a little too complicated for what I want. And if I were to use a paddle wheel, the device would be limited in that the pipe would have to be installed in such way that the wheel's shaft would have to be horizontal, otherwise the wheel would lean its weight on one of its sides and grind against the bushing.
I own a 3D printer, so fabricating a complex part in ABS is not a problem for me.
A sort of astable vibrating mechanism... something like a wiggling snake comes to mind. But I haven't seen anything like it out there ... any thoughts?