How can I detect if a water supply is empty?

[ken123]

I am making my own ATO unit. I want to put a sensor in my fresh water supply that will detect when the water is empty and will send a signal to the ATO.

Anybody have any ideas what to construct this from? Or other ideas?

Two ideas come to mind.
A cork at the bottom of a tube that has a rod or something that goes to the fill hole. On the file hole could be and LED sensor of some type. Need to figure out what to attach the cork to and what that something will ride in. What could I use for a rod and tube?

Or, the not so good way. A float switch at the end of a rod, submerged at the bottom of the container. Not thrilled about this idea. The float switch could be prone to failure being constantly submerged.

http://i11.photobucket.com/albums/a156/ken_nj/jug.jpg

[THE ROOK]

I'd use a float switch. Seal the top of the float. It shouldn't be a problem. Switch will be in freshwater so no salt creep. Also, apparently the other common float failure is "cycling" which comes from waves/current in the sump. The float is continuously off/on/off etc.

[BrassMonkey]

so you want to ato your ato?

[Reefugee]

Not sure why a float switch constantly submerged in RODI will be prone to failure. I would go with the float switch idea.

[ken123]

I read somewhere, maybe on aquahub, that their float switch should not be submerged, that why they sell the optional sleeve that screws on at the top, to protect where the wires enter. And Aquahub's switch is a Madison. I bought another model float switch from McMaster Carr, it's also a Madison switch that looks like it's fully sealed but have not found anything that said it could be underwater all that time.

ATO my ATO? Hmm. I guess that would be having am RO\DI working in my system which I don't have.

Even if I went the float switch way. I guess I could attach the FS to a length of PVC and fashion something at the top to hold it in place.

Just sent an email to Madison asking if their Polypropylene switches can stay submerged.

[therealfatman]

Are you using Kalkwasser or RODI water for your ATO water. If your using Kalkwasser you can use a contuity level relay. Surplus ones are sold on ebay all the time. Or they can be bought new fora round $50. I use Crouzet level relays and use Titanium welding rods for probes, or titanium bicycle spokes.

http://cgi.ebay.com/Crouzet-Syrelec-PNRT-110A-Relay-Control-Pump-Up-New_W0QQitemZ300193352079QQcmdZViewItemQQptZBI_Automation_Components?_trksid=p3286.m20.l1116

Crouzet information on the above relay.
http://www.crouzet-usa.com/catalog/syrelec/NRT.pdf


The above are to turn a pump on or energize a circuit when the level drops. There is also a relay that can be used to turn off a pump or power when they level drops to far, and that is the PNR Pump down relay and that is now on eBay for less than $20. This is what you would likely want to use.

http://cgi.ebay.com/Syrelec-Crouzet-Pump-Down-Relay-Liquid-Level-Controller_W0QQitemZ290277240069QQcmdZViewItemQQptZBI_Automation_Components?_trksid=p3286.m20.l1116

They are not sensitive enough for use with a water with a zero TDS however. Add just a little Calcium Hydroxide (kalkwasser) to your RODI water and they work great.

[ken123]

therealfatman, just RODI water. I buy my RODI from the LFS, don't have an RODI unit and don't work with kalkwasser yet. I stick the jug of FW under the main tank, stick a Aqualifter line in the jug which sends water to the sump. What this switch will do, when it is open (no water left in the jug), will prevent the Aqualifter from coming on.

Just trying to figure how to rig the switch in the jug.

[fodupos]

most float switches aren't water proof because of where the wire goes in... i just used some 1/4" tubing on mine and that protects where the wire goes in...

[therealfatman]

<a href=showthread.php?s=&postid=14281975#post14281975 target=_blank>Originally posted</a> by ken123
therealfatman, just RODI water. I buy my RODI from the LFS, don't have an RODI unit and don't work with kalkwasser yet. I stick the jug of FW under the main tank, stick a Aqualifter line in the jug which sends water to the sump. What this switch will do, when it is open (no water left in the jug), will prevent the Aqualifter from coming on.

Just trying to figure how to rig the switch in the jug.

I was just implying that the addition of just a small amount of Calcium Hydroxide to the ATO water will increase the waters conductiviy high enough to use a conductivity relay. (Say about a teaspoon to a five gallon jug) It would not require you add so much that you would actually detect any difference in your tank calcium levels.

The conductivty relays are not as prone to problems as many of the the float systems. There is no wiring that could potentaially come into contact with your water as the wiring is outside of the container. Only the titanium probes protrude into the container. There are also no floats to get stuck or fill with water and sink. Nor is mounting the probes a problem as is the float mounting. With your water jug you would merely need to drill a few small holes any where in the top of the jug and stick the thin titanium probes the rough the holes. The wiring to the controller are attached to the ends of the probes outside of the jug.

Plus with the conductivity relays they are easy to set up to activate visual and audible alarms such as lights or a buzzer etc. or high voltage pumps etc.

[Origami2547]

Another option is a right angle float switch (go to eBay and search on "float switch" and you'll see what I mean). Just drill a hole in the side of your container and screw it in (it has a gasket). The wires are never in the water.

[BeanAnimal]

Instead of messing with conductivity and fooling with corks and rods, setup a latching relay to fill your RO/DI water jug and use a float valve as a fail-safe.

Trying to get a conductivity probe to work reliably in a setup like this is just not worth the hassle. The same holds true for a "diy" cork type float setup.

Anyway... the latching relay setup will consist of a single relay, (2) float switches, (1) float valve and a solenoid hooked to the RO/DI. It is simple, clean and very reliable.

The lower float will activate the solenoid, the upper will turn it off and then re-arm the latch once the level drops again.

The water will fill the reservoir through the float valve, that is situation just slightly higher than the upper float. If the circuit fails to turn off, the float valve will stop the flow of water.

In turn, the sump can be topped off the same way.

If you are afraid of a runaway condition, then you can replace the lower float with a manual "start" switch that latches the relay to start the RO/DI fill cycle. It will end on its own via the upper float switch, with the float valve as a fail-safe.

Float switches like those in question rarely fail when used properly. If you are concerned about water being forced past the epoxy seal, then you can (as the website indicates) put the floats at the end of a sleeve (PEX pipe for example) and seal the connection with epoxy. The warnings you keep reading are more about liability for misuse. I.E. they don't want somebody dropping the $5 float switch into a process control situation where a failure could be expensive or deadly.

[A.T.T.R]

who cares if the ATO is running when empty

i have a 5 gallon system in a cabinit next to my tank. usesan aqualifter pump . no problom at all if it runs dry.

keep it simple

( also.. DONT TRUST YOUR LFS RO. i livein floridaand we have alot of lfs. i tested alot of RO water.. about the only store at the time that had even close to good RO water was the storei worked at where i was almost always changing the carbon and DI)
buy your own unit you can get a good one ( WPS brand.. they get relabled alot by otehr companys with much higher prices) for about 119-139 ask your lfs

[Origami2547]

<a href=showthread.php?s=&postid=14290184#post14290184 target=_blank>Originally posted</a> by BeanAnimal
Anyway... the latching relay setup will consist of a single relay, (2) float switches, (1) float valve and a solenoid hooked to the RO/DI. It is simple, clean and very reliable.


Not to hijack, but ... Hey, Bean, have you got a economical source for a solenoid valve? Thanks.

[therealfatman]

Conductivity relays are very reliable and require only enough TDS to provide usable conductivity. This is in the range normally provided by water that has only gone through an RO filter. As most reef keepers also use DI filters the relays to be usable need a little boost in the TDS. If there is adequate TDS for conductivity in the relays usable range then conductivity relays are inherently more reliable than the dependance on several mechanical switches, a mechanical float and an additional relay. The conductivity relay cares not whether it is supplying power or cutting power to a solenoid, pinch solenoid, light alarm or a pump.

[BeanAnimal]

<a href=showthread.php?s=&postid=14291911#post14291911 target=_blank>Originally posted</a> by therealfatman
Conductivity relays are very reliable and require only enough TDS to provide usable conductivity. I have plenty of experience with process control sensory devices. I have worked with several types of "conductivity" sensors and measurement products. I have also worked with many ultrasonic, capacitive and pressure sensing technologies (I have a parts bin full of different level sensing devices and technologies). I am currently working with micro pressure transducers to sense actual sump and reservoir levels, just because I can. BTW, that parts bin includes a handfull of Crouzet sensors and LLCs...

In any case, there are a dozen ways to skin a cat. In my opinion, for the novice DIYer, a conductivity sensing setup is just not the easiest or most reliable method available to implement an anti-tds creep configuration. (more below). For a simple idiot light, it will work, but so will a cheap float switch at a fraction of the cost. I love the Crouzet level controllers, but just not for an RO/DI resevoir setup.

This is in the range normally provided by water that has only gone through an RO filter. As most reef keepers also use DI filters the relays to be usable need a little boost in the TDS. Who in the world wants to buffer their top off tank just to ensure that the conductivity sensor works when there are plenty of reliable methods that do not require the user intervention to ensure proper operation.

If there is adequate TDS for conductivity in the relays usable range then conductivity relays are inherently more reliable than the dependance on several mechanical switches, a mechanical float and an additional relay. The reliability of a system is not just a simple product of the number of devices that comprise the system. Your statement is more than a little open ended. In any case you are comparing apples to oranges in this case. My proposed setup is a FULL ATO, not a simple "its full" or "its empty" idiot light or solenoid trigger. That too can be done with a single float switch and relay. Your proposed setup requires the OP to buffer the water to make the system work, the simple float switch and relay are fully self supporting. It would be easy to show the the float switch, in real world application, will be more reliable than a person having to constantly buffer the top-off water.

In other words, the OP simply wants to "sense" the empty bucket to disable the ATO. You have proposed a conductivity relay and constant manual intervention (buffering) in favor of a single float switch and relay that needs no supervision. So $50+ -vs- maybe $12 to do the same thing?

I proposed a system that will refill the RO/DI container ONLY when it is empty, this reducing TDS creep. To get this to work with the proper crouzet (or similar) conductivity probe will still require the user to buffer the 0 TDS water. The sensitivity of the controller will have to be set far too high to be considered reliable.

In a home setup the environment and/or duty cycle will not pose any significant chance of failure but the float VALVE does add a fail-safe just in case. Attempting to use conductivity probes to accomplish the same task will be more failure prone due to the complexity AND operating requirements of the system, not to mention many times more expensive, even with surplus parts.

That said, the level controller listed above (at ebay) is a "pump down" controller. The NRU is the "pump up" controller. http://www.crouzet-usa.com/catalog/syrelec/NRU.pdf How does it work? It is a relay internally wired exactly like the latching circuits I and others have posted. It uses two external sensors, no different than the setup I proposed. The difference? Conductivity vs physical level sensing :)

So that brings us to reliability:
When we talk about reliability, we need to do so within the scope of significance of the proposed project and the possible failure modes and their consequences. We need to also weigh the real world operating parameters before we can decide what system is "more reliable" and at what cost (in time and or complexity).

[therealfatman]

Bean,
I repeat the only problem wth the conductivity probes is the need for enough TDS for a usable level of conductivity. I do not recommend anyone use any type of controller or floats to keep a ATO tank filled as I have seen to many disasaters resulting from floats and switches being used in that manner. Yes it would cost more to buy a Crouzet relay but a self filling ATO tank was not even addressed by the thread writer so really isn't an issue anyway. Besides tying a RODI unit to a small container hardly lessens TDS creep versus a RODI system producing a full 30 gallons at a run into large storage container instead as that does decrease TDS creep. Any TDS changes obtained by the water just sitting in the barrel is usually just a result of gases as nothing is being added to the closed storage barrel. Adding a teaspoon of calcium hydroxide is not much of a chore when it removes the need for dependance on mechaical devices known to be prone to problems. "The difference? Conductivity vs physical level sensing." As long as TDS issues are addressed I chose conductivity over trouble prone physical sensors and the additional cost is worth the lack of worries about mechanical problems.

Besides only you ssem to be addressing automaticaaly filling of top off ATO tank or controls for an ATO yet no ones asked questions about those things so it is you who is comparng apples to oranges as you are not even on the same subject as the rest of us. I am quite aware of the difference in pump up and pump down controls. Yes I did make a mistake as the NRT is also a pump up controller. The NRU is a pump up controller and it uses three conductivity probes a low level, high level and a common. When the water level drops to below the lower probe the power turns on and stays on until the water level rises up to the top probe. The NRT functions as does the NRU but it has a built in delay so as to avoid wave disturbances, has uses a higher probe current and has diffeent probe sensitivity. The pump down control is energized as soon as the water reaches the top probe ie as soon as you fill it, then it de-energizes as soon as the water level drops below the low level probe. Thai means if it was used with a typical double float sytems with a relay to power a pump for ATO it would only supply power to that circuit after the ATO storage tank was filled and would stop supplying power if the waterdropped below the low level probe until the ATO storage tank was refilled. thi is the approprate link for that controller:
http://www.crouzet-usa.com/catalog/syrelec/NR.pdf
It is presently available on eBay for less than $20, not $50.
http://cgi.ebay.com/Syrelec-Crouzet-Pump-Down-Relay-Liquid-Level-Controller_W0QQitemZ290277240069QQcmdZViewItemQQptZBI_Automation_Components?_trksid=p3286.m20.l1116
All in all I would rather use conductivity rather than cheap trouble prone physical/mechanical sensing systems.

[oldsaltman]

therealfatman,
I think the original question was:
I am making my own ATO unit. I want to put a sensor in my fresh water supply that will detect when the water is empty and will send a signal to the ATO.
I would appear to me that he is looking for a way to refill his holding tank with an ATO. I think Bean's and others answers provided that information.:rolleyes:

[THE ROOK]

From his 2nd reply;

"What this switch will do, when it is open (no water left in the jug), will prevent the Aqualifter from coming on."

Sounds to me like he just wants to make sure he doesn't burn out his top off pump.

[BeanAnimal]

<a href=showthread.php?s=&postid=14298235#post14298235 target=_blank>Originally posted</a> by therealfatman
Bean,
I repeat the only problem wth the conductivity probes is the need for enough TDS for a usable level of conductivity. They do not work with RO/DI water. Who wants to be required to buffer their top off water to get an ATO solution to work. The likelihood of "user error" is higher than that of a float switch failure. Also, conductive sensors can interact with other automation sensors (PH, ORP, Etc) and can only be used in electrically isolated tanks.

I do not recommend anyone use any type of controller or floats to keep a ATO tank filled as I have seen to many disasaters resulting from floats and switches being used in that manner. Mechanical floats and controllers are integral parts of process control worldwide. Dishwasher, icemakers, sewage treatment, manufacturing...

To infer that float switches can not be used in a reliable and/or fail-safe system is rather obtuse. For THIS purpose, they make more sense than a conductivity probe.

If you are hell-bent on not using a mechanical float switches, then optical sensors are a MUCH more applicable (and simple) technology for RO/DI applications.

The Facts:
1) Most of the crouzet controllers are nothing more than a latching relay circuit inside a plastic case. The internal wiring is the same as any other latching relay circuit. They have additional electronics to control the sense voltage/current for the conductivity probe. The controllers have the exact same failure modes as any other relay and associated electronics!

2) When used properly, reed switch type float switches have an insignificant failure rate over the duty cycle that an ATO system would expose them to.

3) With proper system design, any system can be rendered acceptably fail-safe. In our case, both the "float" and "conductive" setups are exactly the same in principle of operation and have similar failure rates with regard to controller integrity. However, the "conductivity" setup requires the extra step of regular human intervention, thus increasing its probable failure and offsetting the remote chance of reed switch failure in a float.


Yes it would cost more to buy a Crouzet relay but a self filling ATO tank was not even addressed by the thread writer so really isn't an issue anyway. Yes, I already pointed that out. If the OP only needs a simple "idiot light" then a simple float switch is the easiest and cheapest method.

If he wants the top-off pump disabled when the ATO reservoir is empty, then he STILL needs a latch. Without a latch, the circuit will oscillate and kill the pump. So we are back to choosing a latch driver, either floats or conductivity and the arguments I brought to the table fully apply. I.E, I expanded the context of the conversation, as the relevant details were left out.


Besides tying a RODI unit to a small container hardly lessens TDS creep versus a RODI system producing a full 30 gallons at a run into large storage container instead as that does decrease TDS creep. No fatman. Filling a bucket 5 gallons at a shot will reduce TDS creep and extend resin and membrane life. I proposed the ATO reservoir autofill to automate the task in a safe manner. Lets not get sidetracked please.

Any TDS changes obtained by the water just sitting in the barrel is usually just a result of gases as nothing is being added to the closed storage barrel. Who said anything about TDs changes in the standing water?

Adding a teaspoon of calcium hydroxide is not much of a chore when it removes the need for dependance on mechaical devices known to be prone to problems. Sorry, but that just does not make sense. Full automation vs reliance on human intervention? Both setups have a mechanical relay. Again, in our environment with our duty cycle, there is no problem with a float switch. Furthermore, the proper setup includes a fail-safe to prevent any single (and most double) point failure modes from causing a flood. If you are adverse to the idea of a mechanical float switch, then optical sensors STILL make MUCH more sense than a conductivity sensor.

"The difference? Conductivity vs physical level sensing." You mean conductivity AND physical maintenance vs physical level sensing. Again, for RO/DI purposes, your proposed technology does not makes sense. That is WHY different level sensing technologies are used in different processes. Your proposed technology does not fit the project criteria as well as several other technologies :)

Again, want to get away from physical float switches? Then use optical sensors. They are more reliable than the conductivity sensors and negate the need to buffer the ATO water.

Besides only you ssem to be addressing automaticaaly filling of top off ATO tank or controls for an ATO yet no ones asked questions about those things so it is you who is comparng apples to oranges as you are not even on the same subject as the rest of us. If you go back and read, I clearly pointed out BOTH scenarios and how each sensing technology applied. If we are talking about an "idiot light" then the simple float will work. If we are talking about disabling a solenoid or pump, then the latch and (2) sensors MUST be used to prevent oscillation. Process control 101, fatman. So I am on the same subject and have expanded the dialog to to include the relevant but missing variables and requirements for a properly functioning system. I have done so kindly.

I am quite aware of the difference in pump up and pump down controls. Yes I did make a mistake as the NRT is also a pump up controller. And I kindly corrected the mistake.

The NRU is a pump up controller and it uses three conductivity probes a low level, high level and a common. When the water level drops to below the lower probe the power turns on and stays on until the water level rises up to the top probe. Yes, it is a latching relay, no different than the circuit that uses FLOATS or OPTICAL or CAPACITIVE switches.


As for your lesson in controllers. If I am the guy who pointed out your error, is it not a bit pretentious to attempt to give the impression that you are the one teaching me?

The bottom line? There are far better options for RO/DI level sensing. Conductivity sensors have a place in automation, but so do float switches, optical sensors, pressure transducers, and capacitive sensors. Choosing the proper technology for the task at hand is part of ensuring trouble free, reliable operation.

[oldsaltman]

The Rook,
Could be, but you can't hurt an aqualifter that way. It will run with or without water with no damage.

[BeanAnimal]

<a href=showthread.php?s=&postid=14299285#post14299285 target=_blank>Originally posted</a> by THE ROOK
From his 2nd reply;

"What this switch will do, when it is open (no water left in the jug), will prevent the Aqualifter from coming on."

Sounds to me like he just wants to make sure he doesn't burn out his top off pump.

The proper way to disable the top off pump is to use a latching circuit, so that once it is "off" it can not turn back on until it is

A) Manually reset
or
B) reset by a suitable level of liquid in the top-off reservoir.

If you use a single sensor to disable the pump, the system will get stuck on an oscillation mode that will burn up the pump.

It goes like this:

1) pump turns on
2) water drops below sensor
3) pump tunrs off
4) some water drains back into reservoir from de-energized pump
5) drained back water slightly raises float
6) pump turns back on
7) slight drop in water immediately turns off aqualifeter
8) over and over until the pump dies or enough water evaporates to break the cycle.

We use a simple latching circuit to prevent the short-cycling and add hysterisis to the system... The nice part is that we can use the exact same setup to autofill the ATO resevoir, fully (or partially) automating the process. Adding a float valve creates a level of safety.

:)

[ken123]

Wow, this got real busy! I will already have an ATO with latching relay circuit for my sump, which is under construction. Used Bean's diagram to build it, or those found in this forum.

There are 3 float switches in the sump, 2 for the latch circuit, and 1 as a BACKUP if the upper switch fails.

From responses, looks like the Aqualifter will be OK if it runs dry. Regardless of that, I want to add a 'sensor' to the jug that will tell me when the the fresh water top off jug is empty. It can be mechanical like a float switch or electrical. I can take care of any electronics that need to be done. I don't want to modify the 6 gallon jerry jugs that will go in the compartment under the tank. When one jug is empty, it will be removed and replaced with another full jug. I want a simple 'device' of some sort like in the original picture to detect when the jug is empty.

No RODI unit is involved with this. There is no wave action in the FW supply so a simple 'detector' device like a float switch should be sufficient. The opening to the jug is about 2 inches.

[BeanAnimal]

Ken,

Thanks for the clarification...

A simple float switch and an LED will indicate "empty" but may be prone to the oscillation problems described above. My reccomendation would be to use a simple latch to disable the pump and illuminate a the idiot light.

You indicate that you do not wish to modifiy the containers. Does that mean you want a sensor that can be dropped into the mouth of the jug? How many jugs do you have? Do you want a sensor set and "plug" built into each jug so that all you have to do is attach the harness?

It only takes a single sensor and a latch... A momentary push button switch would arm the circuit. Instead of a mechanical relay, a simple 555 timer IC could serve as a latch. Use an optical sensor and ssr with the 555 instead of the float and relay and there are no moving parts... though any decent relay will certainly live longer than your ATO setup :)

[xrunner1234]

The 3 float ATO is the simplist it can get.

I had one setup using latching relays running in my sump to power a peristaltic pump and another setup that activated my RO/DI filter to fill my 45gal storage tank.

It was totally maintence free running for over 2 years without failure before I moved and broke down the tank. I would evap 3 gal/day and I could go on vacation without any worries.

[oldsaltman]

Here is an image of the one I just made for my new setup. It is controlled by one relay and is a latching circuit. I used two switches at the top as an emergency measure, but it would work fine with two switches. I wired the two top switches in series so if either one fails to move the second will trip the circuit. Old powerhead holders come in handy!
http://i722.photobucket.com/albums/ww223/Saltman/P1010007.jpg

[ken123]

Yes Bean, want to have something I can just drop in the opening, that would be easiest. I have 4 jugs to alternate through. The 4 jugs last about a month for me. I think I have some LED sensors to use. My thought was a cork at the end of some type of rod. The cork would be at the bottom of the jug. At the top would be a 'sensor' or switch, optionally with a latch. I have a 12v dpdt relay I can use if need be, or buy another 555. In a previous thread you said one switch, whatever is used would be sufficient.

As far as the idiot indicator, have that taken care of elsewhere. All I need is this 'detector'. I have these U shaped things. I think they are optical sensors. They look like this (http://rocky.digikey.com/weblib/Optek/Web%20photos/OPB804.jpg). When something is between the U part, it's open, nothing there, it's closed, or vise versa. Then when the cork\rod drops down when it's empty, the optical sensor opens the circuit. That's how I envision it to work.

[oldsaltman]

You can easily use one float switch attached to a long piece of small tubing (to seal the wiring) and wire that to a relay with a light or buzzer or whatever. Total cost should be less that $20. ;)

[ken123]

The spare float switch I have I think is 3/8 NPT. I'll have to wander around Lowe's to see what stiff\rigid tubing I can come up with. What kind of tubing do you have attached to your float switch in that pic you posted?

[oldsaltman]

The piece I used is 3/8" it is labeled with "ZURN PLX" HOT/COLD Potable water and a lot of other stuff that doesn't mean anything to me. It came from Lowes or HD, but both have a similar product, because I have bought it before. I had to use a tap inside the tubing, but I can't remember what size fit the float switches.:rolleyes:

[dwl]

I am considering building something to automatically refill and maintain my ato reservoir levels.
I am leaning toward using 2 float switches, 1 float valve, a relay and solenoid for this but have some concerns regarding the solenoid.
In order for me to avoid TDS creep, it would be benificial for me to run the RO/DI replenishment for a longer period of time, which means the solenoid will be energized for potentially several hours at a time.
Do the solenoids handle this adequately, or is this asking for a failure which could lead to a flood?

thanks

[ken123]

dwl, I defer your question to the experts. :)

oldsaltman, that means nothing to me either. I guess I should be able to find something that small in the plumbing section then. I have a tap that matches my float switch as long I can find something the right inside diameter, I think 3/8" as well. And keeping the wires in the tube will keep them dry. :)

Want to hear from Bean about the optical sensor and\or a latch using one sensor. I think it would be neat and fun to build.

[oldsaltman]

<a href=showthread.php?s=&postid=14300725#post14300725 target=_blank>Originally posted</a> by dwl
I am considering building something to automatically refill and maintain my ato reservoir levels.
I am leaning toward using 2 float switches, 1 float valve, a relay and solenoid for this but have some concerns regarding the solenoid.
In order for me to avoid TDS creep, it would be benificial for me to run the RO/DI replenishment for a longer period of time, which means the solenoid will be energized for potentially several hours at a time.
Do the solenoids handle this adequately, or is this asking for a failure which could lead to a flood?

thanks
Personally I would not trust anything on the RO/DI to work without the possibility of failure. I fill a 32g brute with RO/DI and top off with that. I would never feel safe leaving a 50lb pressure line running to my tank. If my ATO ever fails I don't have to worry about flooding the tank and house because there is never over about 20g in my holding tank. That is my opinion, and I am sure other will have different opinions.:rolleyes:

[dwl]

Ken123,
I am very sorry, Ifeel as if I just jumped in and hijacked your thread and that was not my intention.
I just happened to read one of Bean's posts and it seemed to directly address my situation and prompted my question.

I am not sure what do do here now as I would like to quote the post or at least a portion of it.
Perhaps I should start a new thread.

Please accept my apologies for the hijack.

oldsaltman,
I was not talking about directly filling my tank from the RO/DI, but rather automating the process of filling my reservoir - in your case the 32g brute. I assume that you manually fill your Brute, then let the ATO work from that brute to keep your tank level.

[oldsaltman]

Ken123,
If you get the 3/8" inside diameter tubing your tap should work just like mine did. Good luck.

[oldsaltman]

dwl,
I just don't lke the RO/DI left on anywhere or anytime. I fill my 32g brute with a standard on/off valve and that takes a couple of hours. That feeds through a float valve just incase I forget to turn it off.

[dwl]

oldsaltman,
My RO unit is always under pressure as it provides drinking water for the house. It has the typical drinking water holding tank. The RO output is split with the line going to the DI filters having a check valve on it to keep the drinking water (and it's pressure) out of the DI side. There is a ball valve after the DI filters which is manually opened when I need water. I just want to automate the DI side of things. I do not know what the pressure is at/after the DI filters but the flow is quite low.
I just want to replace the ball valve with a solenoid and control it that way.

[ken123]

dwl, not a problem!

Bean, was looking at monostable 555 circuit for the 'latch'. But please give me any ideas you may have since your last post.

PS. Had electronics 20+ years ago so it's all fuzzy.

[BeanAnimal]

<a href=showthread.php?s=&postid=14300338#post14300338 target=_blank>Originally posted</a> by ken123
Yes Bean, want to have something I can just drop in the opening, that would be easiest. I have 4 jugs to alternate through. The 4 jugs last about a month for me. I think I have some LED sensors to use. My thought was a cork at the end of some type of rod. The cork would be at the bottom of the jug. At the top would be a 'sensor' or switch, optionally with a latch. I have a 12v dpdt relay I can use if need be, or buy another 555. In a previous thread you said one switch, whatever is used would be sufficient.

As far as the idiot indicator, have that taken care of elsewhere. All I need is this 'detector'. I have these U shaped things. I think they are optical sensors. They look like this (http://rocky.digikey.com/weblib/Optek/Web%20photos/OPB804.jpg). When something is between the U part, it's open, nothing there, it's closed, or vise versa. Then when the cork\rod drops down when it's empty, the optical sensor opens the circuit. That's how I envision it to work.

Ken it will be much easier to just attach a standard donut type float switch to the end of a piece of rigid tubing (PEX) and attach that tubing to the lid of the container. The "indicator" and "pump shutoff" will be a latching relay circuit. The lower float is the "trigger", a momentary switch is the "set". It is the same circuit you already built for the ATO :)

[BeanAnimal]

<a href=showthread.php?s=&postid=14300545#post14300545 target=_blank>Originally posted</a> by ken123
The spare float switch I have I think is 3/8 NPT. I'll have to wander around Lowe's to see what stiff\rigid tubing I can come up with. What kind of tubing do you have attached to your float switch in that pic you posted?

Just a pice of rigid PVC or PEX. You can tap the end and use teflon tap or just epoxy the entire float in place :)

[BeanAnimal]

<a href=showthread.php?s=&postid=14300725#post14300725 target=_blank>Originally posted</a> by dwl
I am considering building something to automatically refill and maintain my ato reservoir levels.
I am leaning toward using 2 float switches, 1 float valve, a relay and solenoid for this but have some concerns regarding the solenoid.
In order for me to avoid TDS creep, it would be benificial for me to run the RO/DI replenishment for a longer period of time, which means the solenoid will be energized for potentially several hours at a time.
Do the solenoids handle this adequately, or is this asking for a failure which could lead to a flood?

thanks

Most of the decent solendoids from McMaster can handle the duty cycle. DonW ( i don't see him post much anymore) put many of the different brands through some pretty harsh duty cycle testing (using an automation controller). You may want to get in touch with him to see what brands came out on top. In any case, mostr solenoid valve will fail closed or begin to dribble due to calfication (unless they are on the output side of the RO/DI). The float valve in your container is the fail-safe in case the solenoid fails OPEN :)

[BeanAnimal]

<a href=showthread.php?s=&postid=14300833#post14300833 target=_blank>Originally posted</a> by oldsaltman
Personally I would not trust anything on the RO/DI to work without the possibility of failure. I fill a 32g brute with RO/DI and top off with that. I would never feel safe leaving a 50lb pressure line running to my tank. If my ATO ever fails I don't have to worry about flooding the tank and house because there is never over about 20g in my holding tank. That is my opinion, and I am sure other will have different opinions.:rolleyes:

I fill my ATO resevoir by automation and it fill my tank by automation. For me to flood my tank with fresh water...

I would the simultanious failure of (1) float valve, and at least (2) float switches AND (2) solenoids. I have a better chance of winning the lottery.

[dwl]

ok, so bean, you are saying that a (decent quality) solenoid being energized for 2 to 3 hours at a time is not going to overheat it and cause it to fail prematurely?
That sounds good as it has been the main issue that has kept me from just going ahead and automating the freshwater top off.

thanks and again, ken123 very sorry for the hijack

[THE ROOK]

Oldsaltman - Nice clean setup. I like it.

[oldsaltman]

<a href=showthread.php?s=&postid=14301824#post14301824 target=_blank>Originally posted</a> by THE ROOK
Oldsaltman - Nice clean setup. I like it.
Thanks, that is what I wanted when I built it.:smokin:

[ken123]

<a href=showthread.php?s=&postid=14301326#post14301326 target=_blank>Originally posted</a> by BeanAnimal
The "indicator" and "pump shutoff" will be a latching relay circuit. The lower float is the "trigger", a momentary switch is the "set". It is the same circuit you already built for the ATO :)

The shutoff would be the float switch, equivalent to the lower float switch on the animated diagram, right? But I don't understand where the momentary switch comes in on the 'latch'. The indicator is just that, an indicator.

Let me type this out and see if I get it. One float switch. The water drops in the jug to empty. The FS opens and shuts down the ATO. I replace the empty jug with full. Push the momentary button which releases the latch. Then the ATO can resume operation.
Right? I hope so.