Omega FLR 1000, Руководство пользователя

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2. Product Overview and Principle of Operation
The FLR 1000 series of flow meters and sensors for liquids from Omega
Engineering are capable of measuring flows as low as 13-100 ml/min or as
high as 1.0-10.0 l/min. Highly repeatable results are achieved using a
patented Pelton Turbine Wheel flow sensor design. This proven design
minimizes zero drift while maintaining fast response and linear outputs
with virtually no maintenance.
Flow is measured using a miniature turbine wheel similar in size to a U.S.
dime (16 mm diameter, 0.75 mm thick). The micro-turbine wheel is
supported on a very small sapphire shaft that is held in position by two
sapphire bearings. The micro-turbine assembly is so light that it virtually
floats in the liquid. This relieves force on the bearings and almost
eliminates wear.
As flow passes through the sensor, a precision machined nozzle directs the
fluid onto the very small teeth of the micro-turbine wheel. This causes the
wheel to spin at a speed proportional to the flow rate.
The micro-turbine wheel has alternating white and black sections evenly
spaced on one side of the wheel. An infrared light beam is directed onto
the wheel. As the wheel rotates the infrared beam is reflected off each
white section. The reflected beam is detected by a phototransistor that
converts the reflections into electrical pulses. As the wheel spins faster the
pulse rate increases. Processing circuitry provides analog and/or pulse
output that are linearly proportional to the flow rate
When the wheel stops (under zero flow conditions), no pulses are
generated. Consequently, zero drift is not possible and zero adjustments
are never required.
Every unit is supplied with a calibration certificate detailing the results
obtained during calibration. Units are calibrated using deionized water as
the reference media. Flowing liquids with different specific gravities or
viscosities may effect the calibration.