Average flow loss

Discussion on general flowbench design
ronm
Posts: 78
Joined: Fri Aug 26, 2016 7:08 pm

Average flow loss

Post by ronm »

Is there a formula for how much cfm loss when adding more motors. 1 motor = 100 com. How much cfm loss for adding another 100 cfm motor. Building a 100" bench with 12 motors (LH2093-240).
Tony
Posts: 1438
Joined: Wed Mar 03, 2010 3:40 pm
Location: Melbourne, Australia

Re: Average flow loss

Post by Tony »

Welcome to the forum Ron.

I doubt if you can assume a fixed amount of flow loss for each additional motor added, there are too many factors that can influence the final maximum flow number. The size of each motor is one obvious factor. Adding one extra small motor will not make as much difference as adding one extra monster motor.

But whatever you end up with, trying to force more total air through the bench will inevitably increase internal bench turbulence and internal pressure drops, leading to a slightly lower total available flow.

A one hundred inch bench is a pretty serious ambition.
Just realise that is 520 Lbs of force per square foot, and a square foot of surface is not that large.
Its probably getting rather high for just a bit of glue and a few wood screws, so something totally different will probably be required.
Also known as the infamous "Warpspeed" on some other Forums.
ronm
Posts: 78
Joined: Fri Aug 26, 2016 7:08 pm

Re: Average flow loss

Post by ronm »

Is the 3/4" MDF not enough for a 100" bench with extra bracing? Thanks for the welcome!
Tony
Posts: 1438
Joined: Wed Mar 03, 2010 3:40 pm
Location: Melbourne, Australia

Re: Average flow loss

Post by Tony »

Try cutting a two foot square piece of 3/4 MDF, support the opposite edges between two bricks and drive one wheel your car up onto it.
Decide for yourself if its strong enough.
Also known as the infamous "Warpspeed" on some other Forums.
ronm
Posts: 78
Joined: Fri Aug 26, 2016 7:08 pm

Re: Average flow loss

Post by ronm »

MSG is expensive. Is that a yes or no? Thanks Ron.
ronm
Posts: 78
Joined: Fri Aug 26, 2016 7:08 pm

Re: Average flow loss

Post by ronm »

I mean MDF. Phone has spell check and a mind of its own sorry.
Tony
Posts: 1438
Joined: Wed Mar 03, 2010 3:40 pm
Location: Melbourne, Australia

Re: Average flow loss

Post by Tony »

The maths is easy.

How brave are you ?
Also known as the infamous "Warpspeed" on some other Forums.
Malvin
Posts: 451
Joined: Sat Feb 27, 2010 12:50 am
Location: Pennsylvania

Re: Average flow loss

Post by Malvin »

MDF is stronger then most people please do check it out in this link
http://www.ewp.asn.au/node/6 For got to add this link to

https://www.google.com/webhp?ei=28WyVdO ... elasticity

You can see my flow bench build here http://www.flowbenchtech.com/forum/view ... f=19&t=588
ronm
Posts: 78
Joined: Fri Aug 26, 2016 7:08 pm

Re: Average flow loss

Post by ronm »

Thanks for the info on the MDF. Your bench is fantastic, what are your limitations. With all those motors you could stop the earth from rotating. Lol. Bruce was kind enough to share some bracing info for the large bench. It was the same direction as I was going. Love this site. When I get my computer online I will be able to download some pics from the site. This phone runs out of data plan really fast. Thanks again, Ron!
RACEPUMPER
Posts: 447
Joined: Wed Aug 25, 2010 7:54 am
Location: Riverina Australia

Re: Average flow loss

Post by RACEPUMPER »

Tony wrote:Try cutting a two foot square piece of 3/4 MDF, support the opposite edges between two bricks and drive one wheel your car up onto it.
Decide for yourself if its strong enough.
Not just once either, test as many times as you plan to use the bench over 10 or so years.

Don't forget to place your testicles under the board each time too Ron, because that's how close they'll be when your running the bench.
ronm wrote:MSG is expensive. Is that a yes or no? Thanks Ron.
Don't even think about 100" if you think MDF is expensive, it's the least of your worries

Don't even think about 3/4. 100" is some serious pressure on that front area of a bench. I used 24mm MDF for a 60" bench after testing the MDF in a press and measuring the deflection. For 100" daily usage I would probably double the 24mm or use steel.

Jim
I really love making stuff but don't finish much
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