Low volume flow meter
A system for monitoring the flow rate of a fluid stream to determine if the flow rate meets a predetermined threshold value is described comprising: a light source physically separate from the fluid stream and capable of projecting a focused beam of light through a gaseous and liquid medium; a flow detection device optically coupled to said light source where said flow detection device is capable of interrupting transmission of said focused light beam through said flow detection device at a frequency dependent on the flow rate of the fluid stream to create a pulsed light signal having a periodicity based on the flow rate; a photo detection device which is optically coupled to said flow detection device and which receives said pulsed light signal and converts it to a pulsed electrical signal having a periodicity dependent on said periodicity of said light signal and where said light source and said photo detection device are external to said flow detection device; first retriggerable monostable multivibrator system means coupled and responsive to said pulsed electric signal from said photo detection device and capable of a variable logic output where said output is based on the condition of whether or not said periodicity of said pulsed electric signal exceeds a predetermine periodicity for said pulsed electric signal; second retriggerable monostable multivibrator system means responsive to said first multivibrator system means and capable of a variable logic output; logic means coupled to said first multivibrator means and said second multivibrator means and responsive to a first logic signal from said first multivibrator system means and a simultaneous second logic signal from said second multivibrator system means and capable of outputting a logic function based on said first logic signal and said second logic signal.
- Assignee:
- Dept. of Energy, Washington, DC (United States)
- Patent Number(s):
- A; US 5218346
- Application Number:
- PPN: US 7-694176
- OSTI ID:
- 6453597
- Country of Publication:
- United States
- Language:
- English
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