DIGITEN 1/4 Quick Connect 0.3-10L/min Water Hall Effect Flow Sensor Meter

The results at various rates appear to correlate quite linearly with a r^2 value of 0.9998. Although if you want more precise results than the "38 * Q" figure given by the manufacturer you will have to calibrate the readings yourself.

To address the previous review-- the meter does not report volumetric flow directly. Instead the counts reported represent the speed of flow. Which is exactly why the number changes with flow rate. Volume is then determined by multiplying the cross sectional area with number of pulses and a speed constant while correcting for liquid density, temperature, etc. Certain properties can be disregarded such a temperature, density, etc. and replaced with constants if absolute precision is not required.

Short version-- once you boiling it all down to the basic formula what you need in order to determine volume is number of pulses and time. If flow rate changes over time you will need to slice the readings into smaller intervals and integrate the values.

I'm getting total pulses per gallon all over the map, it sensitive to the flow rate. Does anyone have a schematic of the device?
I also checked the Liters count and measured 331, 515 and 792 pulses per Liter.

Awesome product works as expected. met my needs and Expectations

Thank you

The FL-S402B flow meter is pretty amazing! The quick connects snap right onto 1/4" ID plastic tubing for easy setup. I connected this to my Raspberry Pi and my Reverse Osmosis system with ease. This unit appears to be much more sensitive than FS200A G1/2 meter I had been using, but I will have to do more testing to see how accurate it is. It should deliver 1,380 pulses per Liter, according to data I found online. I'll try to update this review when I learn more about the accuracy.

The plastic locking clips are very difficult to remove, I'm guessing because of the extra sturdy plastic. When I tried to remove them by the tab I just broke the tab right off. I suggest pressing needle nose pliers against the two ends of the clip firmly to pop them off (they will go flying). I have a couple locking clips that are much thinner from some other quick connect fittings, and they are somewhat easier to remove from this meter. Also, the quick connect fitting requires a very clean plastic pipe to prevent drips at high pressure. This is typical of various quick connect products (even some high end ones like this meter), though some are more forgiving that others. Just use a razor blade and make a fresh, vertical, clean cut on your 1/4" ID tubing to make your connection leak free.