Tractorsport Flowbench Forum Archive

Posted: **Mon Feb 25, 2008 6:33 pm**

I have 12 of the ametek motors on my bench but at 300 cfm it will only pull 32 inches/h2o.The motors are the 2 stage that most people use but I will get the part number later.

It is a pitot tube and I have it sealed up pretty good.
The holes in my blower box are 3.25 inches.
The blower box has a circular switching device that switches between the 2 sides of the box.
I have good voltage to the motors.

Any ideas.

Posted: **Mon Feb 25, 2008 6:42 pm**

All 12 blowers running at the same time?

Sealed up "pretty" good?

Did you paint the inside/outside of your blower box?

Posted: **Mon Feb 25, 2008 6:47 pm**

The "valving for your bench (3.25" holes" seems WAY TOO SMALL!). THE SF 600 bench will pull 20" at 600 cfm with 8 motors. The SF 300 bench with 6 motors used to pull about 400 cfm at 20". You either are choking the flow severely with your passage size or you do not have the "Good" ametek 115923 motors.

Tom V.

Posted: **Mon Feb 25, 2008 7:47 pm**

Posted: **Mon Feb 25, 2008 10:31 pm**

Were you flowing a 300cfm plate at 30" or was the bench just the open hole on the top with 300cfm going through your flow element?

I know it sounds like a dumb question on my part, but just trying to get more info . . .

Water or Digital gages ?

Edited By bruce on 1203993121

Posted: **Mon Feb 25, 2008 11:31 pm**

It was with a plate that was calibrated at 300 cfm at 28 inches.
I tried it with your plate and some I had made and checked on a SF 600.

I did some checking and inside the vac motor box there is around 8 to 12 inches of pressure with the 300 cfm plate on the bench.Thats on the side opposite of what is feeding the flow sensor.
I have a digital manometer with 2 ports for the pitot tube readings and from what I understand you just use one port too determine the actual bench depression.

I am actually wanting too flow at least 400cfm at 50 to 60 inches.

Thanks Bruce for the parts you sent me.
I wanted too frame the pitot tube rather than use it.LOL
It was a work of art.

Posted: **Tue Feb 26, 2008 1:06 am**

Maybe I'm missing something here, but if your plate will flow 300CFM at 28 inches, it should flow 320 CFM at 32 inches. If you are not sealed, that 20 CFM could go away. If I am testing right, try this. If this is not right, somebody jump in here! Seal the opening completely then SLOWLY add vacuum to your 28-32 inches. If you are getting flow readings from the pitot, you are leaking. I ran my bench to 44 inches (max for my manometer) and got no flow so I believe that I am sealed.

This may seem silly, but most problems are when you find them! Another thing that popped into my head is the size of the flow element. Are you using 3" PVC, and if so, did you measure the ID? My 1-1/2" is actually 1.57" and the 1-1/4" measures 1.37". A small change at 3" will make a big change in flow (0.1 inch ~ 20 CFM).

Good Luck! -- Doug

Posted: **Tue Feb 26, 2008 8:03 am**

I think we need to know more about the setup of your bench any chance of getting a few pics?

Where are you taking your flow depression (static pressure), flow element static and impact pressure (pitot readings) at?

I'm with Doug you have to verify you have 0 flow through your flow element. A small leak will kill your static pressure.

Posted: **Tue Feb 26, 2008 10:21 am**

I built a very pretty bench the first go round.
It would not meet my needs so I have been building prototypes ever since till I get my design right.
Currently I have a cabinent with a chamber under the flow plates.I am taking the depression reading there.
Then it is piped out the side through the flow element too the air chamber.

I am using the Audie flow quick and I forgot too mention that the 300 cfm was a converted too 28 inch number.
I will get an actual reading at max with the 300 cfm plate.
But with a 300(Calibrated at 28 in/h20) cfm plate it will max out at 32 inches

It is a Pitot tube bench with a 3 inch element.
I used 3 inch pcv white pipe.

I guess as well my main goal is too get as much airflow as possible and get the blower side of it sorted out before I build a nice cabinent and decide on actual flow electronics.
I will post some picks later but it follows the plans Audie sales.

Posted: **Tue Feb 26, 2008 12:08 pm**

Posted: **Tue Feb 26, 2008 12:41 pm**

Posted: **Tue Feb 26, 2008 1:45 pm**

Do have the button on the front of the FlowQuik set to Hi-Depression? It is a known issue that you can only have so much depression with the FlowQuik. Do you get funny lines on your FlowQuik readout when flowing? If you do that means you are overpressuring. That may be the issue with your readings, but not positive.

John

Posted: **Tue Feb 26, 2008 3:06 pm**

John

Yes I do .
You are correct in what you said.

Posted: **Tue Feb 26, 2008 3:09 pm**

I have The 115923 motors.

Posted: **Tue Feb 26, 2008 6:43 pm**

Well you have the "GOOD" Ametek motors.

I think you will get it figured out quickly with some input from the board members. Lot of knowledge here.

Tom V.

Tractorsport Flowbench Forum Archive

Bench Depression low