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| Flow measuring device |
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| tomrux:
Farnell flog a transducer should get you close to what your after. http://au.element14.com/digmesa/932-9506-b/flowmeter-fhksc-arnite/dp/8544700 Tom |
| picclock:
@ yorkie Vaned rotor is the way to go, but no opto. Just fit small earing type magnets to the outside edge of the vane (in pairs so they balance), make the housing of plastic, then fit a magnetic sensor on the outside. That way the vane rotor and it's bearings are fully enclosed with no chance of leaks or fuel contamination. Integrated hall sensors are cheap, 5 for £5 on fleabay and should give good results. Best to get the ones with hysteresis. You will then need to display the info - but I assume you have something in mind for this. Best Regards picclock |
| yorkie_chris:
Seems that farnell one is Ok but flow range may be a bit narrow, seems that one works with the inertia of the fluid hitting the rotor. Also I can't see anywhere on sheet whether it is suitable with petrol. I may make a similar thing just with a close fitting rotor, more like constant volume pump to better measure at low flow rates. Why hall effect rather than opto? I've got some experience using them for speedo setups on the bikes (in fact will be one involved in same thing) but never at small scale like this. I was thinking if I went opto I could use an ally case and drill right through, LED one side, sensor the other and pot them both in there with some epoxy. Actually my first serious electronics project. Thinking of going with Atmega8 chip linked to a 2x16 lcd screen. I want to display current mpg, trip mpg, litres used and battery voltage. I think there should be enough capability in there for that. |
| picclock:
hi Yorkie That sounds like quite a project to undertake. With a magnetic sensor (hall effect) its easy to have a physical barrier between the fuel and the measuring electronics. If you use an opto sensor you either have to measure the interruption of a path of light or a reflection. This means that you will have to use glass or transparent plastic to monitor the rotor, unless you have the shaft come through the casing with some form of mechanical seal (never a good idea with flammable liquids). Also, magnetic sensors are immune to changes of ambient light which can cause issues. Most modern car speedo's now use hall effect sensors to replace the flexible spiral cable. Good luck with your project picclock |
| yorkie_chris:
So with a couple of powerful magnets embedded in the lobes, will that work a hall sensor even with a bit of ally in the way? Or does it have to be directly in the petrol? What is drawing me towards opto is the LED and sensor could be inside, no ambient light at all then, and just the lobes of the rotor to break the beam and trigger it. Nothing to try and stick in the rotor then. For a change the mechanical seems easy. What seems a little difficult is I know no C code, just a little MATLAB... how different can it be :lol: :bang: |
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