PTS Flowbench Forum

I have an 8 motor vacuum box using Ametek 116309 vacuum motors . I made check valves after something I saw online in an air mover link. I need to replace one motor which is now making noise so while I was there I was thinking, maybe I should upgrade the check valves to something better.

The air box it made out of 3/4" plywood and inside of my bench there are 2" openings. There is a 3" PVC pipe to and from my vacuum source.

I can pull 28" of depression up to around 415 cfm. I suspect the check valves I am using are part of the problem but not sure.

I thought I would be able to pull 28" to 550 CFM with this set up. I am also thinking about adding 4 more motors.

Any ideas on good sealing check valves or ways to make improvements?

Any pics of what you are using now for check valves?

I could not upload pictures because the files were too big. I found a PTS post on scupper valves and I ordered 8 of them to replace the ones I have.

What I have now is a round piece of PVC with a 45 degree angle or so and a flat piece of plexi with a hinged door. Gravity holds the door closed normally and the air out opens it.

I will post the difference they make, if any.

3" PVC caps is what I use with the scupper valves I use

I installed a new motor to replace the one that was making noise and changed to scupper valves for check valves.

The scupper valves seal better because I pull more depression per vacuum motor but I am still disappointed that the 8 120V, 122 CFM Ametek motors will not pull more depression on large runner high flowing heads.

I have a BBC 360 cc intake runner that flows 395 CFM as of now and with all 8 motors on it pulls just under 28" depression at .900 lift.

I would measure the static pressure on either side of your 3" pvc pipe and see if you have any differential pressure causing a restriction?

Thank you, I will check it

What is the best way to check the pressure differential?

I do not have a manometer I have digital measuring

Can I add a fitting to both sides of the 3" pipe and attach my depresson hose there to see if the depression reads the same on both sides?

in the intake mode if you put a pressure tap on the suction side of the motor box and pull your max lift flow i am pretty sure you will see a fairly high number in comparison to the lower chamber side of your test fixture box I/e as Bruce said measure across the 3" pipe. 3" id PVC is not sufficient to flow the air needed at that level. In other words you 3" pipe is acting like a restriction. Use two and the problem will go away.


Rick

I regulate depression with an air bleed off valve between the vacuum box and the 3" pipe coming form my plenum box. I would not be able to use two 3" pipes because the air flow sensor is in the 3" pipe

I considered going to a 4" PVC pipe and swapping out the air sensor from the 3" to it

I do have honeycolmb air striaghteners in the 3" pipe, do you think I should try taking them out?