Siphon dilemma with submersible irrigation pump

You can break the siphon by increasing the discharge head. Make the the discharge line an inverted "U" .

A check valve will probably do the trick, as the syphon force won't be enough to open it.

The inverted 'U' will only work if the outlet pipe has a big eough bore to allow it to drain and let the air back into the pipe...other wise add a tall vent pipe to the inverted U.

I designed a gravity dosing system and we had this type of problem, the liquid just wouldn't flow out, even with a reasonable bore pipe until we added the breather.

Hi Del

I guess it is about 6:30 in GB. Do you reply before, after or during coffee?

I did my comment before you but had a chat before I posted it.

Hi...7:40 here!

Yup quick check with my tea and toast!

I've been posting at mad times lately as I twisted my knee and it's been waking me in the night, so I get up, walk about a bit to loosten it off...next thing I know I'm on CR4!

Good morning campers!

PS...Nice to See where you are... I bet it's better weather than here...we've been having bad floods in UK!

Yes CR4 is really addictive.

It is nice and cold. We had some snow about 50 Km from where I live.

We are 30 degrees apart = 2 hours. I thought daylight saving is to can the sunlight and save it for a rainy day.

Hope your knee get better soon. (For the sake of the pain and not the number of posts - My wife broke her leg and it takes time to heal - really grumpy at this stage)

Cheers...

I just had a quick look in the atlas...I'd not really looked at the longitudes before...I was surprised how far east you are! It would be fun to see it all from space, although I don't think those lines of longitude are very visible!

Google-earth displays the data in the info bar.

Cheers.

I would vote for a tall vent line (may only need to be a couple feet depending on the delivery pressure).

The vent will surely work. It can however be replaced with air valve.

You must break the siphon.

An air release or anti suction valve at the highest point in the delivery pipe will do.

It has been a long time since last working with water.

The valve must close under water pressure but must allow air to escape and allow air to be sucked in when the pump is stopped.

One solution would be to raise the level of an intermediate point in the delivery pipe to a level where it is higher than the top surface of the liquid, and install a return pipe from here to above the liquid surface in the container. If the return pipe were to be small bore, or have some sort of restriction in it, then so much the better.

Hey then it would keep syphoning back into itself and you could even run a little wter wheel and generator from the flow!!!

(It's a joke folks.....honest...please...)

Electrically, I'd put a solenoid valve that switches on when the pump is on and off when the pump is off.

Mechanically, I'd use a diaphragm pump where the check valves have springs. Once it stops, the check valves stop the flow.

Another alternative is a perestaltic pump.

I think you and a previous thread poster (slong if I am not mistaken) must exchange equipment. He had a problem with keeping it running.

Yes, very easy, just insert a T connector in your delivery or discharge line. If you have a pressurized line, you can put in a one-way valve on the open line of the T, such that it will open from the out direction when the pump is not running(will close when the pump runs) But if there is very little pressure in your discharge line, simply connect an extension hose and elevate high the open end so that your liquid will not flow out from it. This will effectively break the siphon effect.

If your tank is always above ground, why not raise it a bit further, then all you need is an electric sprinkler valve to allow discharge - no pump needed.

Here in Surrey BC the police would be looking you up by now....Do you hear a Nark-Nark at the door? Just kidding, we have a social problem with grow ops that have many people upset. Your setup sounds like something these people would do, but I know it may also be tomatoes. Years ago I used a bilge pump and experimented with hydroponics in a neutral "fish tank" gravel bed. I never had much success.

Good luck with your gardening.

The simplest thing I can think of is a tiny anti-siphon hole near the top of the pump discharge pipe's arc. Not too high or as the pump runs, the spray from the hole will run out the top of the drum, shooting liquid where you don't want it. Aim the hole at the drum wall if you possibly can. When the pump stops, the siphon will be broken by the air flowing into the discharge pipe through the hole..The pipe can now empty both ways, into the garden and drum when ever the pump shuts off breaking the siphon.

"The simplest thing I can think of is a tiny anti-siphon hole near the top of the pump discharge pipe's arc."

And add a small DWV, Drain, Waste, & Vent Valve to close on water pressure and vent when pump is off, thus preventing splashing etc.
See your friendly plumber, pipefitter of supply store.

Another option would be to reduce the size of your feed line as needed (1/8 or 1/4 " feed line), and raise your reservoir a few feet up, and simply gravity feed through a drip system. The smaller diameter line would allow you to regulate the feeding to your needs.You could even use the drip reservoir as a secondary, which you pump into periodically from the main res. Or even using it as a catch for your syphon effects from the main, but still helping to regulate your drip.

Stop the syphon by making the output line an invertaed 'U` as stated, with a vacuum breaker at the top.

Dear Sir,

What you can do is put a time-control valve in-line with your pump controller. What will occur, is that when your pump is off-line, the time control valve will close. When your pump comes back online, the valve will open. You will have to tie the electronics for the valve in with the power for the pump, at a substantially lower voltage.

If the eventual syphoning of stored water is your main concern or if you are on a strict budget, you can put in a check valve that has a pressure setting greater than the pumps' inline pressure. When the pump comes online, the valves' pressure threshold is overwhelmed and would therefore open. When the pump is offline, the valve will return to it's normal pressure threshold, and will resist the tendency of the water to 'seep'.

Another idea that you can try is putting a loop in the line, at a higher elevation than the uppermost water level of your supply reservoir. That might do the trick.

Waterman

You know, I have an extra hole in my pocket that I just don't need. I'd be happy if I could just send it to you. I just don't know how to attach the hole to an E-mail.

Install a vacuum breaker or open check valve at the top of the syphon. When the pump is running, the pressure keeps the vacuum breaker or check valve closed. When the pump stops, air pressure opens the valve or vacuum breaker and stops the syphon action.

Am I missing something here? Get rid of the pump; fit a tap.

It looks to me like he needs the pump to force the liquid through the the piping at a constant rate, and for timing the Off/On cycle. A tap would work, but the drum will have to be raised high enough to equal the pump discharge pressure and if there is not a mounting hole for the tap one must be added to the drum. And then the tap would also need to be automated for the Off/On cycle by using a solenoid valve.

As an option for a different I would usw a peristaltic pump.

They work by squeezing and releasing a flexible line in a curcular motion.

Typically when it stops at least one of the pump cams will have a tight nip on the line preventing siphoning on the line. see diagram below

They also work great for recirculation fluids

alright, here it is...drill a very small hole, an eighth of an inch say, about 2-3 inches above the discharge port of your pump. What will occur is that when your pump comes online, the water will jet through the hole, and back into your reservoir. When your pump goes offline, the small perforation will prevent the pipeline coming off your pump from building the downstream suction head, or syphon-effect. It's easy, quick, and effective. W

The hole needs to be higher, but not so high as to squirt out the top of the drum. That way if the run cycle of the pump is short, the hole will be above the final water level, breaking the siphon. If the hole is below the water level when the pump shuts off, the siphon will not break until the water level is drawn down enough to expose the hole to air.

"Are there any other solutions, such as a "breather" or "vent" tube place somewhere inline?"

Simplest solution of all is a small "snifter" valve mounted at the high point of the siphon line. Actually, en effect, a small check valve that closes to prevent loss of pumped fluid and opens when pump stops to open and break the vacuum!

A small plastic ball check should fill the bill!

Easiest way is to get an anti-siphon for a dishwasher at the hardware store. Stands up to the force of a pump, hot water and chemicals and is cheap! -- JHF

Provide a clip after stopping the pump to avoid siphoning. Remove the clip begore starting the pump.

DHAYANANDHAN.S