flapper valve, wrong?

[cspeier]

IMO, I've been doing lots of research on this flapper valve. I even went as far as talking with Ametek and visiting with this old dude who has been working on vacuum cleaners for 50 years. (hard as #### to understand by the way) .

I think putting the flapper on the intake side of the motor isn't doing anything. It may still protect the motor, but I'd lay my left arm on the fact that the motor is still spinning backwards. Air always find the shortest path correct? Well my feeling is the air is still going to go thru the motor.

I think putting the flapper on the exhaust side and killing the problem from the word go. The flapper would need to be mounted on the outside of the box or PVC pipe. I think the deflection, turbulance, and whatever else is going on inside that cabnet will push the flapper closed resulting in sealing off the motor. In all honesty, a flapper on both sides is probably the ideal way. Then you have cooling issues, and whatever else might be occuring inside that cabnet.

So tell me, am I in the weeds on this? I just don't see anyway possible the flapper on the intake side(flapper being pulled open) will stop the motor from turning backwards. Please tell me if i'm wrong? I plan on testing this theory, and well let you know 100%.

Chad

[larrycavan]

Agree...I vote for valve on exhaust side of motor. Stop reversion at the source location or the motor is going to spin anyway....maybe not as fast as without any CV but I still think it's going to spin. The valve probably needs to be larger though. You want the air out ASAP to keep the motor cool.

Bruce...this looks like another job for D.T.

[86rocco]

As long as you can prevent air from flowing backwards through the motor, it shouldn't matter whether the the check valve is on the intake or exhaust side. You can see my design for a valve on the intake side in

[cspeier]

I understand that rocco, I'm saying with that design, the motor is still turning backwards. Maybe not as fast, but it's still going to bleed back thru the motors. It actually has no choice. If you put the flapper on the outside, by nature the presuure will keep it closed. This will 100% stop any flow thru on the motors.

Chad

[86rocco]

I can't see why. With my design, the check valve is positioned so that the flapper normally falls closed by gravity and pressure that backs up through the motor will push the valve even more tightly closed, there should be no flow. True, the motor casing and valve are pressurized but that doesn't matter, pressure without flow would not cause the motor to spin.

[larrycavan]

The air in the exhaust side plenum will be anything BUT laminar so I doubt if there will be constant uniform pressure. It will be different for those motors that are furthest away from the exhaust opening than it is for those directly facing it.

The only proof positive would be to try it on "your" bench cabinet design both ways and see what you get.

If you simply build the check valve on the exhaust side of the motors, you can be assured the problem is solved.

JMO