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spunding valve

f-e

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I'm guessing not, but has anyone seen a pressure release valve on the end of a drip manifold?

https://www.aliexpress.com/item/400...earchweb0_0,searchweb201602_,searchweb201603_

That's the fruit of much searching. If you understand ca fuel rails, you have this sussed already.

I use 1/2" hose, but just my short run holds 500ml. That's over a third of a watering session, as I'm every few hours in coco. That's the first third that gets used. The third that soaks out through the coco. They keep a lot of that 500ml which has sat in a hose, under my lights, for hours.

I use typical arrow drippers rated 2L per hour. That's if supplied with a Bar, and my pump is 1.4 Bar. I have 0.4 Bar's worth of pump spare.

I can put this spunding relief valve at the end of my line, and as the line pressure goes over it's set point (I choose the full 15psi/1Bar) the valve lets the excess pass. I can send it back to the tank, to aid mixing.

This means, some of the water that sat about for hours, goes back to the tank. Replaced in my manifold by water from the tank. Which is better maintained, using my aerator (I keep meaning to build a pneumatic dampener for, so I can use it)

This will also ensure, that as long as my pump can supply over a Bar, the drippers will see a Bar. It's a pressure compensating valve for the entire manifold. So as my filter fills, chipping away at my 1.4 Bar, the drip rate won't be effected.

It seems right... but I'm not seeing commercial applications in our industry. Then again, I don't see many pumps that can work a dripper properly either. We are poorly catered for, which is really quite surprising. Very few drip system users here will be able to reach the Bar that most kit is designed for. Though it only takes a fist sized $20 pump. With that in mind, my next level proposal is a Mars mission..
 

f-e

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After some thought, it seems my excess 0.5bar will return 200ml per min down 3 meters of the 5/16th pipe. It's just not going to scale well with these parts.

I'm going back to plan A. I'm going to open up the far end of my manifold with a full bore sized solenoid valve, not a relief valve. I will only need to it for a few seconds to change the entire lines contents. Then I can close the valve and let the pressure rise to drip like levels. As I run 12v and 1/2" hose, it's a $15 project.

$5 for a 3/4" 12v solenoid.
$3 to put 1/2" hose barbs on it.
$3 for a monostable? 555 board. Just a timer board with relay. One that operates for a few seconds at power up, then stops. My pump is 12v so they just wire to the same timed supply. That will give my tank the 'whoosh' I'm looking for to.
Edit: If you don't run 12v, add $2 for a 12psu to plug in beside your pump.
Ghetto lover? Go scrap a washing machine. Then Electrocute yourself :)

I guess it's a purge valve.
 

f-e

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Found a valve. https://www.aliexpress.com/item/32829997020.html
I need the 'drain' version. Many of these need water pressure to keep the valve seated shut. With just tank head, they can weep very slowly. The drain version is for low pressure use. It has a tougher spring inside to keep the thing shut. This means it needs to open as the pump starts, or be used with a pump with just 8 meters of head. Any more pressure behind the valve, with it's tough spring, and it won't open. In this project, it's opening before the pump has barely turned so I'm golden.

The weeping of other styles is a concern for siphoning back really slowly. Once the pump is off. I actually fitted one today that drips after the pumps off, not while it's on. Very slow drip, but still, I need the low pressure type. For now, I must keep the return pipe out the water (at the tank) but I want it to mix the tank, not make noise.

The control gear is real simple
https://www.aliexpress.com/item/400...=20210527203740159263545302940010538889_4&s=p
Reads that it waits 0-10 seconds before power on, but it's a change-over relay. Move the wire between the nc and no terminal to make it switch off, not on.

The biggest issue is the valve being 12mm. I will probably slip some 12mm pipe over, just to fatten it up.
I notice in the reviews that someone claims the orifice is just 1mm, but I reckon they got a dud. It's a standard housing, of which I have used a few.
 

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