which bench to build

[DaveW]

This will stir things up a little.

I'm reading back and forth between the orfice bench and the pilot bench and can't figure which way to go. I know more about the orfice bench construction and how it's supposed to work. Question I have is what is the problem's with the pilot bench?

Can you get accurate results when flowing exhaust ports?

Do you have to change orfices if you were to flow 50cfm vs 200cfm?

Do you have orfices?

Just seems so much easier to build. (I will be going digital either way)

[Mouse]

Dave,

Both methods have about the same accuracy potential, typically 1% in a good setup. However, both require good construction and layout. You have to know a little bit about the methods for a good return on accuracy and repeatability.

I happen to prefer Pitot tube. There are no orifices used in a Pitot tube system, except maybe to calibrate.

John

[84-1074663779]

Either type of bench is capable of excellent results, I am a heretic and prefer the orifice type bench.

My reasons are that I can build and calibrate a complete orifice bench myself at practically zero cost. It is simple to understand what is actually happening.

To build an electronic pitot bench means purchasing the flow measurement computer and trusting what it tells me. Nothing at all wrong with that, I am a retired electronic engineer too !

It really comes down to personal preference and what you are used to.

[DaveMcLain]

I've got a Superflow 110 bench that I use at our shop, it's obviously an orfice plate type bench. From my understanding the orfice plate benches are used a lot for several reasons. They are inexpensive to build, they are easy to calibrate accurately and they are ratiometric meaning they don't require a lot of complex atmospheric correction calculations. What condidtions effect the part being tested also effect the orfice plate an equal amount and thus cancel out.

So the choice is up to you. When I use my Superflow I generally will use about 3 or 4 different ranges throughout the test so that I'm always flowing above about 75% on the inclinded manometer for the most accuracy. Changing the ranges with rubber stoppers along the way is not a big deal to me.

[Mouse]

[84-1074663779]

I doubt if anyone can successfully argue that either type of flow bench is actually superior to the other, it really comes down to personal preference.

Either type will work fine if it is well built and used with care.