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Unread 04/03/2012, 04:43 PM   #6
uncleof6
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Quote:
Originally Posted by sefrayser View Post
I made a Durso for my 90 gallon corner. It has a 1" bulkhead and I made the Durso out of 1 1/4" pipe with a reducer at the bulkhead. I have a Mag 9.5 pushing water with aprox 5' of head. I have the pump gated back with a gate valve and it is about 1/4 closed. I started with 9/64 hole and have worked my up to 1/4 hole. The water level is constant but I still have the gurgling sound. I have the discharge pipes about 1-2" under the water in the sump. I also have them on gate valves and have them gated back a little. I tried putting a piece of air line tubing in the hole and the level started to raise and lower. I put a valve on the air tubing and it did the same thing. What can I do to quite it down a little? I have the "L" that comes off the standpipe about 2" under the water or 2" under the overflow fingers. By making the hole bigger water does that do?
The noise is due to the flow rate to the tank, the 1" bulkhead, the valves in the drain line, the tee in the drain line, and the fact that it is a durso standpipe.

The flow rate for durso standpipes, is low--this is inherent to the design. When the flow rate becomes to high, the pipe becomes too full of water (over 1/4 full,) and water no longer flows on the wall of the pipe, with calm air in the middle, as it should for silence and reliability. The "laminar" flow rate is rather low, probably below 350 gph for the 1.25" pipe, and the 1" pipe below the bulkhead, though you did not state the pipe size.

There should not ever be a valve in a drain line, unless you have a dry emergency back up, especially with a durso--as it causes turbulence (air and water mixing) and presents a plug hazard. Flow rate is never controlled by a valve on the drainline, rather a valve on the pump return. Durso or any drain lines should not be split to feed two different sections of your sump, as this causes issues with open channel drains (dursos) and may cause issues with siphons as well. Never restrict, with a valve, any drain line unless it is a siphon, with a dry emergency.

Durso standpipes, are never quite quiet, never quite reliable, never quite stable. They are designed for low flow systems, where the flow rate is such that these problems do not occur.

Reconfigure your drain without the valves, tees, splits, elbows, and run it as straight down as possible, use 45°'s if needed, but 90°'s will cause turbulence (noise). Don't add gimmicks as they don't work without an associated reduction in flow rate, and in fact without the gimmicks, reducing the flow rate is part of the cure, often the whole cure. The hole size, is never the same between any two systems, and is an unreliable tuning tool. Lowering the flow rate and increasing the pipe size cures the problem. Or convert your drain system to a siphon system. Siphon systems are silent and problem free ("Herbie" can and does show some instability at times)


Mag 9.5, you are using 1.5" return pipe as per the instructions yes?


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