Pressure Sensors & ION Eyes

[garfield at pilgrimhouse.com]

On Mon, 11 May 1998 13:15:49 -0700, goflo at pacbell.net wrote:

>MPX5006  0 -.87 psi, 3% accuracy

Yeah, I saw that one too. Might do to have two of them, 5010 & 5006, to
switch between, depending on where in the larger range of pressure, you
were operating in. At the cost of these gizmo's, it's not wasteful to
use BOTH together, one at the high end, the other at the low.

Since it's common for eXperimenters like ourselves to work around either
10, 15, 20, or 25" H2O, having both sensors available seems like a nice
fit of ranges.

>This could be useful for measuring dP across a sharp-edged orifice, 
>which I think somebody on the list is doing. Also Pitot tube sensor 
>apps.

Yeah, I think you're right. I thot SteveG (or someone!; I'm losing it
here), was gonna use these instead of fluid manometers in their
otherwise std orifice-based FB.

That's a good point about Pitot tube apps too, I hadn't actually
considered that until you mentioned it. Hmm, airspeed indicators!!
Angle-of-attack indicators. Lot's of possibilities.

>Thanks for the motor controller stuff - Think I'm gonna take a shot 
>at it. Roger the tedium of flow testing! I do a lot of it. Am very
>interested in automating these things.

Lemme know if I can help on your "thyristor" controller end. I'm gonna
be driftin over to speed-controlling this whopper 3-phase AC Paxton
blower I just ordered, but I'd like to help out to cover BOTH bases, if
you need a hand. I'm at your service in the cause of FB science. B)

>> If any of yous guys can find a MAF sensor that's
>> available CALIBRATED, and within +-1%FS accuracy over say 300cfm 
>
>Concur with your observation that repeatability is the main thing with
>flow testing, so I'm missing something here. Linearity perhaps?
>Please elaborate.

Nah, yer not missin a thang; the ONLY reason I was interested in
ACCURACY rather than simple repeatability, is that sometimes you're
dealing with devices like manifolds, carbs, etc. that are supposedly
rated for a particular cfm & water-drop. And so I'd like to be able to
check these ratings out, as well as maybe spec to precise numbers my own
stuff, so they can be compared to OTHER people's results. Repeatability
is fine as long as you're working on that very same bench all the time,
but if you wanna exchange stuff with other people, and compare notes,
you also need ACCURACY. I agree, it's right to consider it a
second-order effect, but it's a nice "second".

But to be honest, I'd think that still the 3-5% accuracy of these
present devices is adequate for my needs, so I'll settle for 3-5% if I
can't get 1% at the moment. Just wait a year or so, and they'll be at 1%
accuracy anyway! B)

Cheers,
Gar