Vacuum motor check valves

[jcisalive]

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?

[Brucepts]

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

[jcisalive]

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.

[Brucepts]

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

[jcisalive]

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.

[Brucepts]

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?

[jcisalive]

Thank you, I will check it

[jcisalive]

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?

[1960FL]

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

[jcisalive]

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?