another newbee - help

[plshd]

I'm new to this board and need some help to get in the right direction.
I help out the #1 pro-fuel bike (FBMracing.com)and want to build a NICE flowbench,and have been studying and reading up on the MSD style bench.Its simple but has a lot of downfalls,
What I'm looking for is any dwg.s (auto cad.dwg.s would be nice)of good bench design.
I'm thinking I want to pull about 28''of test psi.and have a max cfm around 970.
The plan is to use 10 vacuum motors.The part I don't like is the orifice disk and the location of its hole.
Another thing that has not been clear to me is the inclined manometer and its divisions,like- do the divisions get marked flat or do you mark it in line ( inclined)?seams to me that there should be an easy er way.
One thing I plan on doing after reading alot of posts about it,is to use pneumatic cylinders with a o-ringed plate to seal the side doors,one three-way solenoid,two cylinders and one switch should do the trick.Im working on the same thought for the motor openings,this can run off the motor power to a solenoid to be automatic each time a bank of motors is turned on.what do you think?
Thank you for any help you can pass on.
I hope to be able to do the same someday.
Paul

[Mouse]

Hi Paul,

Welcome to the forum.

One thing most everybody has done to an orifice style bench is loose the rotating disk of orifices in favor of a single sheet of orifices and plugging unused ones with corks, or making the orifices bolt-in. Not as convenient as a rotating disk, but the rotating disk is just too unreliable in sealing in home made benches.

One way to avoid the infamous inclined manometer is electronics. You can avoid a lot of design problems and complications with orifice ranges and calibrations by using electronics. You will also hear a lot of dissagreement on this issue too.

Hope this helps a bit.

John

[Tony]

Welcome to the Forum Paul.

As Mouse says, there are plenty of choices on how to construct an airflow bench. The MSD design has quite a few fairly serious inbuilt problems and is not a particularly good example to copy.

There are many choices. The first is, do you plan to reverse the flow through the whole bench when doing intake/exhaust measurements ? Or you can build a bench with two test holes on top, one sucks and one blows, and flow is always in the same direction. That can simplify things a great deal.

The next choice is the method of flow measurement, orifice plate, or pitot tube measurement ?

An orifice bench can either use a rotating turret to change flow ranges, or another way is a series of orifices in a large plate and rubber stoppers to block the unused holes. Both have advantages and disadvantages.

A pitot bench can either use a conventional sloping manometer to read flow, or electronic measurement using a computer to read out flow figures.

There are also some interesting alternatives to using multiple vacuum cleaner motors. How about using a supercharger or industrial high pressure blower driven by a single large electric motor ?

There is no "best" way to do it. Read through the previous threads here, we all have some very different ideas on how best to go about building an airflow bench. Adopt whatever ideas appeal to you, and suit your needs and budget.

My own bench uses two test holes, a single centrifugal blower driven by a three phase variable speed motor, and an eight position orifice turret (two feet in diameter), and water manometers.

[cboggs]

After using commercial benches for years with rotating orifice discs
and the problems that go with them , ..

I built my bench with a plate with three orifices to get a total number of
7 ranges, .. uses rubber stoppers, .. and I LOVE IT !!!!!

Now if I could just stop blowing the cabinet up I'd be OK

Curtis