A sad day in pitot land . . .

[bruce]

I spent this morning dismantling my old pitot style flowbench. With the new PTS orifice bench up and running with PTS digital gauges my old flowbench was just outdated and taking up valuable floor space in my shop.

[msj442]

all the more reason to think i made the right choice on my build. sorry for a sad day bruce, but like they say "keep moving forward".

max

[jfholm]

I have my black arm band on for you and will think of you when I see my Flowquik and orifice in a tube. :;):

John

[larrycavan]

One small step for man.....One giant leap.....Well, you know how the rest of that goes..... :;):



Edited By larrycavan on 1234511522

[49-1183904562]

Bruce?

Now how are we going to test the DM and FlowSoft for the Pitot Guy's!

:p

Rick

[bruce]

We got Doug, he's a good "guinea pig" . . . . . . I didn't say I threw the parts away, just got rid of the big ole box in the shop. When you see my shop you'll know why I took it apart for the room.

I can put the parts back together if/when the time comes for that.

[slracer]

Hey Bruce, That's an insult! I have some very nice guinea pigs for friends! -- Doug

[Tony]

Ah Bruce, this is like a religious conversion.
Away from the pitot sect, and being baptised as an orifice bench true believer.
May the force be with you.

Moving your pitot bench is highly symbolic.
A great many of the orifice followers were concerned that you had been seduced by the dark side..
All hail the mighty orifice.

[GordonE]

Bruce, can you explain why you think is better with orifice benches?
I am now running my pitot with a 2.5" mesuring pipe. And it seems that I can get good accuracy without switching measuring elements.

I understand that its more comparable with superflow benches, but for me it seems better to strive towards accuracy than a flowbench standard.

Regards Gordon

[Tony]

Absolute accuracy is far less important than repeatability (for what we are doing).

A constant fixed unvarying error can be lived with.
Something that has a changing error from hour to hour and day to day can drive you nuts, because nothing ever repeats.

What you really want to know is, has a certain subtle modification gained or lost a very small increment of airflow since the last time it was tested. And that could be one hour ago, or two years ago.

The beauty of an orifice bench is that no corrections are necessary to make very repeatable measurements. You just measure the percentage flow on your sloping manometer, and that never changes, day, night, summer or winter.

The trick here is that the exact same mass of air flows through first the test piece, then the reference orifice. The "quality" of that air makes no difference to the readings. The relationship between the two resulting pressure drops always stays the same.

A pitot bench on the other hand, will read differently every day, and you need to precisely compensate for the temperature and barometric pressure every single reading you take. That is laborious and prone to errors creeping in, even if it is all done with a computer.

[bruce]

Tony summed it up but let me add . . . simplicity of design. Simple plate change if I need to change ranges as apposed to different size flow elements. Reverse flow is also a dream to do, flip a plate and slider, throw two toggle switches and change a Cd if required in the software. Maybe 1-2 minutes total and you are flowing exhaust.

Plus, I'm using my PTS bench design with my PTS digital manometer and not someone else's product anymore. That in itself was a symbolic event!!



Edited By bruce on 1234616330

[jfholm]

[larrycavan]

Why I can remember the days when I was attacked for making statements like some of the ones in this thread.....Ohhhhhh how times have changed :;):

[Tony]

Larry, I believe the level of knowledge and understanding here has increased hugely, because we each share our ideas, experiences, and knowledge freely and openly.

Some other Forums are unfortunately infested with egos, and aggressive commercial marketing.

[bruce]

What can I say Larry, you had a big influence on my "change"

Tony's post hits it on the head as to what this forum represents to those wanting to build a flowbench, a non-hostile place to go and find the info and the people to help them along no matter what style they choose . . .

Larry, you've been in my shop and know I lack floor space so something had to go.