Liquid Level Switches

[Gr33k R33f]

Hi all,

While still planning things for my new tank, I am trying to solve a few issues.


1) I need to control a small powerhead that will top-off the sump with RO/DI water (both turning it on when water level is too low and shuting it down when level is too high)

2) Also I need shut-off the two return pumps (EHEIM 1262) in the case something goes wrong with the 2 Durso StandPipes.

So I am resorting to liquid level switches (like the ones here: www.floatswitches.net). Problem is that they are limited as far as the voltage/current needs of the device they control (230V over here in Greece) and watts capacity is also low.

Does anyone has any tried & proven alternatives to propose?
Needles to say that budget is indeed an issue, so the cheaper the better!!!

 

[fungia]

i think the ultralife float switch can also do 220v. it is rated to do up to 10 amps in 110v or 5 amps in 220v. email ultralife to make sure first. but it is a lot more expensive. the floatswitch.net is the cheapest i have ever seen .. $6 each!

 

[Gr33k R33f]

fungia thanks for the input on ultralife. It's rather pricey (trying to cut all corners w/out sacrifices for my future inhabitants) so I think I will resort to a DIY setup.

Will probably use a plastic floater and gravity feed RO water for top-offs.

For controling the two pumps I am thinking of adding a relay to withstand the extra voltage and use the 6$ float switches to control the relays (if I could only find a descent DYI diagram with parts list for this one!?)

 

[Gr33k R33f]

I finaly managed to get my paws ..errr.... fins.... errr.... hands on the 220V floaters I was looking for.

Next obstacle is to control one solenoid valve (when idle it restricts water through it) with two floaters. I need to open the solenoid (and allow water through) when either one, or the other floater indicate a low level in the liquid they monitoring.

Has anyone managed a successfull implementation like the picture below?

Floaters (F1) and (F2) are in parallel, and in the normaly open position, and control the power to the solenoid.

When either of the floaters detect a low level, they close the circuit and the solenoid gets power to allow water to go through (the solenoid is pressure rated to hold the necessary pressure from the tap).

 

[Anonymous]

There are several flow switchs available that work with 10 V AC. You need a powersupply for the float switch and the solenoid. Using household current (110-240 VAC) is dangerous, and should be avoid at all cost. You are forewarned.

Other comments:
1, solenoid is using for low-flow application only. Make sure you have the correct type that can handle the flow rate you need.
2, solenoid also need to have the correct contact/wetted material. You don't want to use any of them that has brass/copper part that is in contact with the saltwater.

 

[Gr33k R33f]

Thanks for the warnings seven ephors... I am not 100% comfortable myself with the 220V being so close to water so I have taken all necessary precautions (on the floaters, I added extra insulation with blobs of silicone, splash guards etc...)

The solenoid is indeed pressure rated for the average tap water system and there is no metal touching water.

In any case, this solenoid controls water into a six stages RO/DI, then sump/refugium with heavy skimming (X4 on the liters), then a prefilter, then a Fluidized Sand Filter, so even if something does go wrong, there is a lot of filtering, mechanical, chemical and biological before that water hits anything alive in the tank.

But I digress.... back to the question.

Do you think such a parallel connection of the two floaters will achieve the ‘either-or’ effect for the solenoid that I am looking for?

 

[Anonymous]

Listen, for a few euros, you can get a powersupply and a 12 V solenoid. It is not something to use even if someone pay you to test it out. 220V AC can travel across any wetted surface, and in salt water, it is as good as the wire they use to bring the power to your house.

Unless you put my name in your will, please consider what you hear.

As for the parallel connection, it will work as you expected.

 

[Mihai]

I agree - look around for PC (personal computer, not power compact) sources from old computers - they have 12V. Don't go 220V!

As for the parallel connection, it will work as you expected.

This all depends on wheather the soleniod and the switches are "normally open" or "normally closed". But you probably checked this before you designed the scheme, right?

M.

 

[Gr33k R33f]

Thanks for the help, I got my paws on a 24V solenoid valve that can handle the water system's pressure, and the setup work like a charm.

If I can only figure out a safety in the case that the solenoid gets stuck open!?

Any takers???....

 

[Mihai]

Sure, you can use a mechanical float valve that closes when the level goes above some level that is set above the level of your float switch. Thus, if either your float switch or the solenoid fail, the float valve will be your second check. And you can go further and add another solenoid in series with the first (also with a switch above the first). Really, you can add as many solenoids as you want for arbitrary reliability, although two levels are probably sufficient as long as you notice the first failure before the second one fails.

M.