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Re: Fertilizer pump fix...

>I've picked up a cheap used IV pump that I want to convert for use as a
>fertilizer pump.  Everything seems great, except it keeps thinking the >fluid
>isn't flowing.  Somehow I need to fool or disconnect the flow meter.  It
>seems that the flow meter is an optical sensor next to the pump head.  Can >I
>just open it up and disconnect it?  Can I somehow fool it into seeing the
>flow?  Any ideas how this thing works?  Any ideas how to make it work?

Hmm. Does the flow sensor detect the SHAFT ROTATION or the FLUID'S MOTION?
There are basically three ways the sensor could be detecting motion of
either the fluid itself or the shaft of the motor:

1 - The fluid BLOCKS light from the detector, thus no light = flow
2 - The fluid TRANSMITS light to the detector, thus light = flow
3 - The fluid motion or shaft PULSES the light going to the sensor, thus
BLINKING light = flow

1 and 2 are easy to "fool". Use some black paper (or color some paper with
a sharpy (beefy black marker that bleeds badly on paper) marker) and block
the detector or emitter if (1), play with some aluminum foil acting as a
mirror if (2), but (3) is tricky. A simply circuit could be build around a
555 timer chip to fool a pulse-detector. You might also try shining an
infrared remote control at the detector since it will generate a pulsed IR
light output when active. Chances are that if you open up the unit you'll
find the sensor is connected to a relay or other switching circuitry/device
of some sort. If you bypass the switching part, you should be OK. Remember
that many metering pumps are NOT CONTINOUS DUTY though, so be sure to cycle


Waveform Technology
UNIX Systems Administrator