PTS Flowbench Forum

Stuart, thanks for looking. There is no housing. It is as you see it. The circuit board was made up by the mfgr. of the flowbench who went out of business around 2000. Don't know where the sensor came from but someone here on the forum suggested that it looked like an automotive maf sensor. It's very sensitive to changes in humidity. I'm wondering if it can be replaced with something similar without the sensetivity. Don't know how to check the value. I would assume checking voltage with the unit running ? Just thought it may have been farmiliar to you or someone else on the forum. Thanks again, Jim

This is not an automotive application sensor but most likely a scientific one, start your research here.

http://en.wikipedia.org/wiki/Anemometer

Without having sensor wire numbers it will be hard to determine what it actually is and what the calibration is, i am pretty sure it is not a standard that all are the same.

And everything you wanted to know about Hot wire anemometers.

http://www.dept.aoe.vt.edu/~simpson/aoe ... irelab.pdf

Rick

Thanks for the info Rick. I'll look. Do you still have the 1960 FL? Believe me, I worked on many of them. Cut my teeth with Knuckleheads though. The heads didn't flow very well in those old dogs. Jim

Jim, No i keep loking for another set of 1960 cases so i can build another little something, you know like most i don't have enought projects

Rick

Rick, thanks for the reply. I used to have a ton of that old HD stuff but got rid of it all. Good luck but sounds like your too busy like you said. I looked around for people who sell anemometers. Checked Digikey and tried to look into Boston Scientific with no luck. Any suggestions? Jim

Try searching on "thermal mass flow sensors"

lots out there.

Rick

Hey all,
I ordered some time ago 6 Lamb By-Pass Two Stage Ball Bearing Vacuum motors, which came in yesterday!!!!
The specs say these motors are able to produce 98 cfm each @ 100"wc.
Down to Lowes I went and picked up a sheet of 3/4" plywood.
I built a 12" x 12" x 48" plenum and cut (so far) 3 5.75" holes to mount the motors.
I spaced them starting 5" from the bottom at 10" on the front, 3 additional holes willbe spaced starting at 10" from the bottom on the RH end at 10".
On the LH side, I cut a 4.0" hole and radiused the edge with a 3/8" round off router bit centered on the bench plenum.
On the cabinet (flow bench), I removed the RH side cover and plenum end, Once I finish the plenum, it will attach and become the RH closure for the flow bench plenum.
I had previously built my own vacuum source, supplemented by 3 shop vacs, but quite frankly, it scared the hell out me whenever I used it! Although it was enclosed within a steel housing, a 13" diameter nylon prop turning at 40,000 rpm... I think you get my point!
Beside the inherent danger with running that beast, it was also extremely loud- my gf called it a screaming banshee!


So the bottom line is that I just wouldn't use it, and only use the 3 shop vacs, which regulated me down to only 12" - 14" max water column.


Hopefully, these Lamb motors will be able to produce enough cfms at 28" wc to give me standardized results.


The design goals for my bench are:
1. Self Contained
2. Portable
3. Easily modifyable / convertable (to orifice style if the design limits are reached or exceeded or ???)


OK, now for the questions:
Can I control all 6 motors with one of the Harbor Freight Router Speed controllers (without burning up the controller?)???
(Specs are 1050 Watts Each, i.e. 9 Amps)
Is the spacing or orientation of the motors critical or affect the performance?
Should I install a 4" 90 degree elbow inside the source plenum to help direct the flow towards the motors? (any gains to be had here?)
Has anyone used these motors? Do I have enough yet?
I did leave enough room for additional motors to increase capacity in the future if needed...
I'm a bit concerned about having enough electrical power (I'm limited here)...

Just a quick note on the Harbor Freight controller. I use one and tried it on just 2 motors and it would get uncomfortably warm. I think 6 motors would kill it.

John

Why not just have one variably controlled motor?

SSR wrote:Why not just have one variably controlled motor?

That is exactly what I do now, until I get the big bench built. I run it up as high as it can go with the controlled motor and then turn it down and turn on the next motor and take it back up to the test pressure.