my latest bench design idea

[JRM]

wanted to get some input

[Nick]

There needs to be a settling chamber between the head adapter and the orifice plate. One of the problems with the MSD is the orifice sees turbulent air because the test piece is directly above the orifice. I agree with Tony who said, the settling chamber cannot be to big. (keeping it together is the hard part) An orifice will flow more if it is being "blasted" vs being open to undisturbed air.

These are just my opinions, derived from reading on this board, and what comen sense tells me. It may work I just don't see how it could be accurate.

Nick

[JRM]

thanks for the input nick.
Part of my reasoning behind this idea is if you look at some of the pilot style set ups they are using an oirfice in a tube. For lack of a better word a pipe then ori/restrictor then back to a pipe then the head fixture. Hope that makes sence.

[bruce]

A pitot style flow bench does not use an orifice plate in the tube. Its either a single pitot tube, multiple pitot tube or an averaging tube that does the "work".

You can build an orifice style bench with an orifice plate in a tube but as discussed on this forum in past posts your readings are going to be off due to the way the air will flow thorough the orifice disk. More reading on this can be had in past postings on the orifice area on the forum.

[JRM]

Thankyou for correcting me. I misunderstood the pitot setup

[84-1074663779]

What you have there would work pretty well I would expect, if it used a pitot tube flow measurement system in one or both of the PVC tubes.

For an orifice bench, I would place the orifice in the vertical bulkhead where you have shown the vacuum motors drawn. The vacuum motors could then be located just behind the orifice on a second bulkhead. A large settling chamber ahead of the measurement orifice is absolutely vital.

That would then look pretty much like my bench. I just have two large chambers with two test holes and a central orifice turret located vertically on the dividing bulkhead.

My blower is located in the left hand chamber and blows straight up into the outlet discharge test hole.

Keeping the flow always in one direction, and varying motor speed to adjust the flow vastly simplifies everything.

[bruce]

[larrycavan]