Nick's bench

[Nick]

It works. I finally got to test my bench today. It seams to work great. Heres how mine works. It is an orifice type, with the orifices in the middle of the bench. The large clear deck plate is removed to change orifices. I used rubber stoppers to plug the holes. So far they do not have to be moved from side to side when changing from intake to exhaust. They stayed in there under 36" of water with no problem. The most they will ever see in 12.5", (height of my incline scale) This setup works great. I thought it might be a pain to open the plate and change stoppers, but it only takes about 30 seconds. The flow direction is changed by opening the deck plate on the end, (by the monitor) Two more plates are in the bench, one for intake and one for exhaust. There are 2 blast gates on the other end of the bench to also control flow. The blast gates work ok, but a deck plate for the exhaust would work better. To bleed off pressure, I wanted to try different devises, so I did not put anything inside for now. I picked up a 1.5" gate valve to try. It works good. Very easy to control the depression. I need to get another one for the exhaust.

The manometers are very steady, I was worried they might jump around like some have said but they don't. I can get within an 1/8" of the depression I want

I made my own calibration plate, so I'm not to sure how accurate it is. All my orifices are 1/8 plate machined to within .001.

So here are some numbers. The CD seams to be in the .59 range to make the numbers come out right. That could be the calibration plate. I need to get one from someone and compare.

Calibration plate size 1.612 1/8 square machined edge.

All my numbers are corrected to 28" water

Orifice size 2.052 2.295 2.514
Depression
28" 187 188 186
25" 185 186 187
20" 185 186 185
15" 182 185 182
10" 182 183 184
5" 180 180 178

It is interesting to me that the numbers go down with the depresion. Any one know why?

I would like to say thank you for everyone who posts here. This is a great project. Without this board I would not have built this bench.

Hope I don't sound like I'm bragging, I am just happy it works!!!!!!!

I will post a few pics to show how I did it.

[Nick]

I wheeled it out side the test room to take the pic.

[Nick]

This one is my $10 manometers. Using water and food coloring for now. Anyone know the sg of antifreeze?
I would like to use FP1 but that's not in the budget for now. I also want to add overpressure protection. It took me all of about 20 minutes to make a mess. LOL

The pressure taps are 1/8" brass tube, about 3" long, drilled through the top of the bench.

[Nick]

This is of the orifice plate before it was painted and sealed.
I am using rubber stoppers to seal the unused orifices. It is installed in the middle of the top chamber, that is 17" deep 24" wide and 72" long.

I have lots of pics if anyone is interested.

[Nick]

Last pic, This shows how it works, should be self explanatory.
This is before the 2x2 bracing was added. (very important)

I wont post any more pics. might make Bruce mad.

[bruce]

No need to worry bout posting pics, everyone I am sure likes to see what others are doing.

I upgraded my hosting plan so I have plenty of room . . .

[Nick]

Well in that case, maybe a couple more. I am interested in what other members think. Thoughts, suggestions, hints, criticism, go easy its my first bench!

This pic shows the blast gates and the gate valve, used to bleed off pressure to set the desired depression. I will need to add another for the exhaust. I would like to try a few other things as well.

[Nick]

There is lots of room for motors. These are surplus center 2 stage. The wiring is a little "GETO" but it works. Each motor is on its own circuit. The connections should be in a box.

[Rick360]

[gofaster]

It looks like a good sturdy bench! You were smart to leave room for more motors later. Congratulations!

[larrycavan]

[Rick360]

The range correction factors I wrote about in my earlier post based on different test pressure are in the table below. These are from a manual for a 300cfm blue brand bench :;): which has ranges based on 25" test pressures.

Doing a little math with the numbers in this table would give you corrections based on cal pressures of 28" if that's what your calibration is based on.


Test *** Intake ****** Exhaust
Press*** Factor ****** Factor
-----------------------------------------------
36" *** 0.989 ****** 1.009
28" *** 0.997 ****** 1.003
25" *** 1.000 ****** 1.000
20" *** 1.005 ****** 0.996
15" *** 1.010 ****** 0.992
10" *** 1.014 ****** 0.988
5" **** 1.019 ****** 0.984

Hope this helps.

Rick

[Nick]

Thanks, Rick That puts the numbers within 1cfm. Close enough for me. The Mercdog spread sheets average to the next cfm anyways, so that formula could be right on. Also I have noticed when the pressure drops below the 30% line the numbers are not correct. I need to read up on how to make an accurate calibration plate before I get to carried away here.

I did not know that the numbers would change with pressure drop when I machined the orifices. I machined them without using the correction factor. (hope that makes since) So instead of my flows being exactly 50 100 150 200 250 300 they read a little higher. Hence the reason the cds are lower.


Also, is anyone else using the Mercdog spread sheets? I have found a few interesting things about how to make it work correctly. If your cd numbers are all over the place, you need to change the pressure drop in the first column in the first calibration sheet to 12.27, or whatever your inclined scales height is. I was told that it should be 28" but that cannot be correct. Set it at 28" and you cds will be all over the place.
I am not sure why they picked 12.27 for the height of the scale, its a little strange to me. If I knew the scale is the same for any height I would have made it a more convenient number.

Lot's more to learn. Learning this a week ago would have been nice!!! :angry:

It will still work great, just not the perfection I was after. Instead of doing the math in my head while testing I will have to use a calculator, or the spread sheets. :angry:

Nick

[Nick]

I had a chance to do some exhaust testing to night. Here are the numbers.

Range Intake Exhaust

4 186 185
5 183 186
6 185 187

I am impressed that the numbers are so close to the same. I did not change the cd. I was reading that on most benches, the exhaust flows more. Here's why I think mine is different. #1 The motor heat does not go into the bench. #2 the orifice plate is the exact same on both sides.


I found one more interesting thing tonight. I was looking for a 5cfm leak. (intake and exhaust) Check out the picture!!!! this explains why super flow paints the inside of there benches
Wheres my paint can?

I sprayed it with soap and water.

More work, lot's to learn

Nick

[larrycavan]

Nick,

A friend of my once worked for Gliden paints. He got me some kind of epoxy paint 13 years ago. It's held up well to water getting on the bench from the hose when the floor gets sprayed down. Not one bit of deterioration and easy to wipe down.

Larry