Herbie drain won't siphon - air leak?

[bronch]

Still plenty of bubbles even with the drain pipe terminating closer to waterline. I assume 30ish minutes should be long enough for the line purge itself of air, right?

Tried lowering flow and readjusting the valve but all that does is create more densely packed, slower moving bubbles lol

 

[BairCorals]

Can you show a picture of your overflow with the drain valve all the way open so I can see what it does?

 

[bronch]

Can you show a picture of your overflow with the drain valve all the way open so I can see what it does?

This is with the valve wide open. Lots of gurgling, as you would expect.

Thank you all for your help, by the way!

 

[Sisterlimonpot]

I'd imagine that the air bubbles are coming from the water fall from the weir.

That's a unique setup and adjusting the gate valve to get that waterfall to not create bubbles when it goes over the edge will rule out bubbles resulting from that.

 

[bronch]

I'd imagine that the air bubbles are coming from the water fall from the weir.

That's a unique setup and adjusting the gate valve to get that waterfall to not create bubbles when it goes over the edge will rule out bubbles resulting from that.

Maybe I'm not understanding something but I have the water level set deliberately high so there is no waterfall coming from the weir when the valve is adjusted:

?

 

[ryanjohn1]

Should there be another pipe in the box that is a bit lower than the emergency one?

 

[BairCorals]

Yeah im at a loss, I would adjust to about halfway between those two photos. If it's still happening then I have no idea.

 

[Sisterlimonpot]

Yeah im at a loss, I would adjust to about halfway between those two photos. If it's still happening then I have no idea.

Well, on a herbie the total flow through the sump, pipe diameter, and overflow area play a big role in if you have to allow water to trickle over the Emergency. On a bean animal design the emergency needs to remain dry and the fluctuation is assumed by the Open standpipe.

@bronch it certainly seems like from the last photo you shared that the air isn't coming from overflow, like I expected. Unless that water level is fluctuating over time. It looks like you have the gate valve adjusted close to where you want it.

Your suspicion that it's getting pulled in from somewhere down the line have to be correct. Now you just have to start eliminating the culprits.

 

[BeanAnimal]

I am nowhere near a computer and also don't have your flow, pipe or valve sizes to do the math. However, it is possible that the restriction in the valve (resulting pressure drop) is causing cavitation as the water exits the valve. This would manifest as loud noise and bubbles at the pipe exit.

You may also be drawing air on someplace along the pipe, or even along the valve stem. The valve stem seat may work well under pressure, but leak under suction.

I would do a few things here.

1 - drill holes in the discharge pipe at, or just above the water line. This will allow the trapped air to escape and relieve pressure in the lower half of the pipe. This will allow the siphon to purge faster and may significantly reduce the entrained air.

2 - try moving the valve closer to the sump/discharge. If possible I would also remove the valve temporarily and try various restrictions or placing the valve at the end of the pipe to see the results. This will help rule in or rule out cavitation.

3 - try a smaller pipe for the siphon. The velocity will be higher, but the valve restriction will be less. If (as mentioned in item 2, you can't MOVE the valve, then try the next smaller pipe size from the valve to the sump. Again, this is counter intuitive, as the velocity will be higher, but the pressure drop between the valve and the rest of the discharge will be lower.

"Pipe Dope" or "Pipe joint compound" - Just to clarify the advice from others. only use pure PTFE based products, don't use anything else, as most have various oils and hardeners in them and/or can even have powdered metals in them.

Rectorseal 2 is fine. It does have fibers in it to help prevent it from washing away. Use this in the threaded pipe joints.