Water pump, siphon effect, air bleed valve, etc.

Hot Diggity Sog

Hot Diggity Sog

Well-Known Member
I'm still designing my first automatic watering system and I don't fully understand a few topics. I put together a simple mockup and am hoping for some feedback and knowledge.

Water Feed.jpg

My reservoir will be between 1 and 2 feet below the height of the main line, depending on the level of the res. I don't really understand how I would be at risk of the siphon effect when the pump shuts off but I'm told I am. Having a small hole, or valve in this case, that drains back to the res when the pump is on and lets air in when the pump shuts off seems like the common technique but water pressure is a valuable commodity and having a hole or open valve will certainly reduce pressure (I would think).

I have been preparing to add an air bleed valve at the very end of the main line and have it be several inches higher than the highest water point. I still don't full understand what purpose this is going to serve. I was told to do it, but not *why* to do it. Is it going to help flush the left over water in the lines? Is it supposed to reduce the risk of a siphon?
 
Last edited:
2cent

2cent

Well-Known Member
Hot Diggity Sog said:
I'm still designing my first automatic watering system and I don't fully understand a few topics. I put together a simple mockup and am hoping for some feedback and knowledge.

View attachment 4745194

My reservoir will be between 1 and 2 feet below the height of the main line, depending on the level of the res. I don't really understand how I would be at risk of the siphon effect when the pump shuts off but I'm told I am. Having a small hole, or valve in this case, that drains back to the res when the pump is on and lets air in when the pump shuts off seems like the common technique but water pressure is a valuable commodity and having a hole or open valve will certainly reduce pressure (I would think).

I have been preparing to add an air bleed valve at the very end of the main line and have it be several inches higher than the highest water point. I still don't full understand what purpose this is going to serve. I was told to do it, but not *why* to do it. Is it going to help flush the left over water in the lines? Is it supposed to reduce the risk of a siphon?
Click to expand...
Exactly what i thaught of THAT. And then add a non return valve to the return piece would allow no water to escape but air to get in right?

But doesnt this make the system guzzle air down also?as it passes the ait hole... Or the fact that the pump pushes past it does it not effect current?act like a venturi i guess?

My pump came with a nozzel with an airline attachment on it. Right on the pump says it adds oxygen maybe also stops syphon?
Airlocks?
 
2cent

2cent

Well-Known Member
Hot Diggity Sog said:
This is all new to me so I'm trying to learn and understand the principles.
Click to expand...
Yeah same res been below always now new water butt is tall lol.

U got a non return vsle u could put on the end and test? See if water syphon stops still it wil stop water exiting.

And if so fill a bucket timed both wayd to see if the valve open effects water delivered
 
Hot Diggity Sog

Hot Diggity Sog

Well-Known Member
2cent said:
Yeah same res been below always now new water butt is tall lol.

U got a non return vsle u could put on the end and test? See if water syphon stops still it wil stop water exiting.

And if so fill a bucket timed both wayd to see if the valve open effects water delivered
Click to expand...
Yeah...I'll try that and see how it goes. I'm temped to build an entire mockup out of clear 3/4" tubing so I can see exactly what is happening.
 
.Smoke

.Smoke

Well-Known Member
When the pump shuts off, the water in your system is still moving due to inertia. With the lines being pressurized with no air in them, it allows the water to create a "suctioning pull" on the reservoir. Since objects that are in motion want to stay in motion and there's minimal friction, the water is able to keep enough momentum to pull itself through the pump, up and out the reservoir, draining it until it creates a natural "air break" that stops the suction. (Aka. Your rez is empty).
That's why you create your own air break.

You only need the slightest "leak" for it to work, so if you're worried about pressure loss because of the ball valve, you could get your smallest drill bit and drill a hole in the bottom of the pipe feeding the valve.
Just make sure you get your hole line up so it shoots back into the rez. Otherwise you'll be cutting that pipe and trying again. :)

Edit...I'm no scientist, but I did make a living as a licensed plumber for a while.
 
2cent

2cent

Well-Known Member
Hot Diggity Sog said:
Yeah...I'll try that and see how it goes. I'm temped to build an entire mockup out of clear 3/4" tubing so I can see exactly what is happening.
Click to expand...
Did think about that would be ideal eatched youtube vid guy shos u can watch the bubbles to seeif u got it in the right place then u watch the syphon break.

But he uses the pin hole method i dont wan spray fountain lol can this hole be a 4mm feed tee in te 19mm line and a pipe down to the water in resfrom the bleed hole? Or does it have to stay open high
 
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