Modified Durso for CPR Overflow

[verbal]

Hey everyone,
Just wanted to show some pics of a modification I've come up with for a Durso-inspired standpipe in a CPR overflow. I tried this design first:

http://home.att.net/~rstockman/overflow.htm

However, there was too much turbulence created as the water flowed through the holes. I then tried the square notch in the standpipe in place of the holes, but this was no better for me. I had turbulence and, hence, loud noise.

I tried to come up with a way to create more laminar flow down the pipe. I thought why not just put another tube in there to break up the turbulence.

I toyed with some flexible tubing at first but then discovered CPVC. I use 5/8" CPVC tube inside the 1" PVC standpipe. I reamed a hole in the original PVC cap large enough to accept the CPVC, then capped the CPVC with the appropriate cap with some holes drilled in it.

There's some pics below.

I have a 600gph CPR overflow matched with a ViaAqua 3600 pump in the sump. I guess we're probably getting 400-500gph of flow, and this standpipe has handled this nicely.

[verbal]

Another photo:

[verbal]

One last shot:

[Matt Rogers]

NICE WORK VERBAL!!

I'm floored. You are a PVC artist! [smiley=beatnik2.gif]

Any shots of it in action?

[verbal]

Here it is in action:

[Matt Rogers]

Wow that's smooth. I don't see any turbulance. I think you nailed it! Nice work.

The over flow holding area on the pre-filter looks like it is sealed? Is this true? and how does this work?
I have heard alot of bad thing when pretianing to CPR overflows so I don't know much about them and never seem them in action.
I really want to know what I am looking at to cut to the chase here.

But it looks cool Verbal. Karma coming at ya.

[verbal]

The overflow holding area has a loose fitting acrylic top. The big complaint with these overflows is that air eventually builds in the U-turns of the siphon, slowing siphon rates until, potentially, all siphon is lost. CPR has manufactured these units with a port on top of the U-turns to allow hobbyists to remove this air as it builds up (either by mouth or via a pump).

I must admit that I do see air collecting at the top of the u-turns. I know this slows my siphon rate. I have not however lost siphon entirely, even during power outages. I do suck the air out of the u-turns everyday, though. The standpipe modification has no impact on this property of the overflow.

Here's a picture showing the air evacuation port and where the air tends to trap. Hope this helps.

[verbal]

And here's a schematic of flow through the unit.

[Matt Rogers]

I don't see that as a unique flaw to CPR overflows.
In the old school overflows, I'd get air in the u-tubes too. I'd have to stick an air-line up there and suck it out occasionally. Your way looks easier.