I don't know if anyone has anything specific in mind, but you could peruse GlobalSpec's collection of Gas Flow Switches. [shameless plug]

Is it possible to use two lines, each housing a check valve in opposite directions, so flow is forced through one line while going forward, and flow is forced through the second line while moving reverse? Then you can use a simple cost effective flow meter in each line, and determining direction of flow is foolproof.

just a thought...

Otherwise, I'm sure someone somewhere makes a device that you are after, as long as you have the to spend.

If you are still looking for one, then continue HERE

The google search just brought us back here, and the links underneath weren't very helpful. "C" for effort, "D" for usefulness, and "B" for relevance :p

That is a very bad score card indeed. Will think twice before putting a link.

Here are some manufacturer of air flow switch. Please search among their range of products. With some luck, you may locate a suitable one.

Thanks,

Been searching all day, will continue. Cannot yet accept the fact that this product does not exist.

Wish you good luck dear Ron Shorts

Does anybody make a 1/4, or less flapper valve arrangement to put at the top of the pipe at a joint? Then a position sensor on the output shaft to measure angle and convert that to velocity?

Should be able to sense direction and velocity with some contraption like that.

Simple enough. LynDoor™Ind. might have something.

Yes, SIEMENS makes an airflow sensor, that is directional sensitive. It is a spring loaded paddle connected to a microswitch. It is installed by screwing it into a cutout on the duct. Sensitivity is changed by the size of the paddle. It is working from low flow to what I consider medium flow environment. Very reliable, having used for decades. Sorry, no part numbers, as I did not need that for a long time.

It is so simple, that when you get my drift, you can build an adequate one in a day or two.

What the heck you mean with insertion style is nebulous: any sensing has to be in the inside anyhow, the switch may or may not be.

Thanks for the feedback, will investigate the Siemens solution that you've recommended. I probably should have indicated that my application is in 4", 6" and 8" pipe. When I referred to "insertion style", I meant inserted via a thread-o-let, versus a flanged or threaded "inline" version.

Many Thanks,

Post # 13 If you Google as suggested, sail switch you will get more leads.

I suspect you will have better luck searching for a "sail switch".

These are usually a polyester foil sail mounted to a microswitch. Honeywell does bidirectional ones.

Mark Bingham
Relativity PL

Have you tried Honeywell, Johnson Controls, KMC COntrols, Dwyer or Emerson Rosemount? -Dave