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Automotive Air Mass flow meters
http://byap.backyardmagazines.com/forum/viewtopic.php?f=8&t=22697		 Page 1 of 2
Author:  Stuart Chignell [ Aug 18th, '14, 12:19 ]
Post subject:  Automotive Air Mass flow meters
Does anyone on the forum know much about these and what they do?

Can they be adapted to measure air flow in an AP aeration system or for airlifts?
Author:  Colum Black-Byron [ Aug 20th, '14, 12:19 ]
Post subject:  Re: Automotive Air Mass flow meters
I've changed them out before.

But it shouldn't be too hard to hack into to make work if it'll fit, and the flow is enough to set them off. A flow meter from a turbo would probably be too slow for most air pumps to match up with. Most automotive sensors (older ones, I don't know much about the newer ones), work on a current that can be detected to tell what the value is. Usually power, signal & ground.

Signal can be hooked into an arduino, and the results can be pulled up on a computer, or set to do different things. So if X is below X, set alarm off.
Author:  Stuart Chignell [ Aug 20th, '14, 12:35 ]
Post subject:  Re: Automotive Air Mass flow meters
Thanks C. Well that is a start.

I ask because mass flow meters as a process fitting are expensive (~$3000) so less than $100 for an automotive one if it could be persuaded would be cool.
Author:  Colum Black-Byron [ Aug 20th, '14, 12:40 ]
Post subject:  Re: Automotive Air Mass flow meters
What are you planning on using it for? Just to detect if the air pump is working?

It'd be fiddly to calibrate.
Author:  Stuart Chignell [ Aug 20th, '14, 12:44 ]
Post subject:  Re: Automotive Air Mass flow meters
Well if it really is a mass flow air meter it should be able to tell you the mass of air flow. To do that it would need a pressure sensor, temperature sensor and an air operated velocity sensor.

Getting all of those would be cool as well as the combined value of air mass flow.
Author:  Colum Black-Byron [ Aug 20th, '14, 12:47 ]
Post subject:  Re: Automotive Air Mass flow meters
But what would you do with the information once you've got it?
Author:  Stuart Chignell [ Aug 20th, '14, 12:53 ]
Post subject:  Re: Automotive Air Mass flow meters
Temp would be useful just cause.

Pressure and air flow would be good to monitor air pump performance and to keep a log or air delivered to a system.

Would give really good input data for aeration trials and experiments.

Lots o uses.
Author:  bunson [ Aug 20th, '14, 13:26 ]
Post subject:  Re: Automotive Air Mass flow meters
Cheap (possible) option: grab a PC fan and an arduino/raspberry pi. Put the fan in the air-flow and hook up the wiring, measure the interval between the pulses generated in the fan and equate this to some calibrated volumetric flow. (the fans have minimum velocity for this to work so may need some more reading).
Author:  Bodgy [ Aug 20th, '14, 13:34 ]
Post subject:  Re: Automotive Air Mass flow meters
I'm not up to speed these days but I think most air flow meters are "hot wire" type.
They don't have multiple sensors but use a heated wire (heated by electrical resistance), as the air cools the wire the current or voltage changes (depending on design). The mass of air is calibrated off the change in V or A.
There are actually two wires in the spare one I have and just looked at, not really sure what the go is but from reading your posts I'm sure you guys could work it out faster than I could. :shifty:
Author:  Sleepe [ Aug 20th, '14, 14:33 ]
Post subject:  Re: Automotive Air Mass flow meters
As Bodgy said there are either hot wire or vane.
Air flow into an engine is complex there are many variables to get the correct fuel air mix.
You would probably better off with a vane as its a potentiometer and quite simple(? spelling, bugger that was the pot).
All they measure is the angle the vane is pushed to by the airflow the don't really measure air mass.
As with Bodgy my go faster days are over but IC engines pull a lot of air or ram it as in a turbo or supercharger.
You could always bodgy the spring on the vane and the calibrate it with some known airflow but its not air mass. :)
Author:  Charlie [ Aug 20th, '14, 18:13 ]
Post subject:  Re: Automotive Air Mass flow meters
Missed this one. Sleepe is spot on, but additionally MAF (mass air flow) sensors are specifically designed per each model and brand of engine taking into account induction and exhaust flows and pipe sizing as well as a bunch of other things. In other words if you removed a MAF sensor from a Nissan 3L turbo and fitted it to a Prado the information wouldn't make sense to the engine control. Similar if you had the know how and hardware to hook it up to a compressor the outputs from the sensor wouldn't be worth anything because it is trailered for a particular engine design. You would need manufacturers resistance values etc which may prove to be difficult.

Older sensors may be of more value but I think you may be looking at a brain ache with minimal advantages. Someone with electronics knowledge may be better to assist as I can only offer my heavy machinery and diesel car experience.
Author:  Stuart Chignell [ Aug 20th, '14, 18:21 ]
Post subject:  Re: Automotive Air Mass flow meters
I don't want to fit one to a CAR.

:upset:

Its to use to measure air flow in a aeration system.
Author:  Charlie [ Aug 20th, '14, 18:33 ]
Post subject:  Re: Automotive Air Mass flow meters
Huh, but your trying to use an automotive air flow sensor with an air compressor. Are we not on the same page here?
Author:  Stuart Chignell [ Aug 20th, '14, 19:03 ]
Post subject:  Re: Automotive Air Mass flow meters
Sorry Charlie my eyes glazed over and I didn't read the last two sentences of your first paragraph :oops:
Author:  Stuart Chignell [ Aug 20th, '14, 19:03 ]
Post subject:  Re: Automotive Air Mass flow meters
Sorry Charlie my eyes glazed over and I didn't read the last two sentences of your first paragraph :oops:
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