HCL chlorinater

[gerharddvs]

Hi,
I'm looking for a circuit/design to build a HCL chlorinater. The one where U put electrodes in HCL and generate chlorine gas. Don't want to fill my pool with salt.
I can use stainless steel electrodes which is much cheaper then those electrodes they use for the salt chlorinaters. I just don't know enough about chemistry to build a control circuit.
Any ideas?

 

[ericgibbs]

Hi,
I'm looking for a circuit/design to build a HCL chlorinater. The one where U put electrodes in HCL and generate chlorine gas. Don't want to fill my pool with salt.
I can use stainless steel electrodes which is much cheaper then those electrodes they use for the salt chlorinaters. I just don't know enough about chemistry to build a control circuit.
Any ideas?

Look at this thread How does this circuit work he's talking about chlorinators.


https://www.electro-tech-online.com/threads/how-does-this-circuit-work.40940/

 

[gerharddvs]

No that's a salt-water one. I'm looking for a the hydrochloric acid (HCL) one. With this U have a tank with the acid in it and some electrodes and by sending the current through the electrodes it generates chlorine gas wich U then feed back into your pump via a venturi.
I'm just looking for some control circuit that will limit the current and switch off / indicate when the acid needs to be replaced

 

[Mikebits]

Sounds unsafe to me.
https://www.electro-tech-online.com/custompdfs/2008/09/MSDS_Chlorine.pdf

 

[ericgibbs]

No that's a salt-water one. I'm looking for a the hydrochloric acid (HCL) one. With this U have a tank with the acid in it and some electrodes and by sending the current through the electrodes it generates chlorine gas wich U then feed back into your pump via a venturi.
I'm just looking for some control circuit that will limit the current and switch off / indicate when the acid needs to be replaced

hi,
I would go with Mike on this one.

Chlorine gas is hazardous.

 

[gerharddvs]

Not really. That process generates very little gas not like when U use gas cylinders. That's why U need the venturi to suck it up. I think your dry chlorine is more dangerous then the little gas coming through there. Keep in mind that your salt chlorinater also generates about the same amount of gas and for the acid...U use that regularly to maintain the pH in your pool.

 

[ericgibbs]

Not really. That process generates very little gas not like when U use gas cylinders. That's why U need the venturi to suck it up. I think your dry chlorine is more dangerous then the little gas coming through there. Keep in mind that your salt chlorinater also generates about the same amount of gas and for the acid...U use that regularly to maintain the pH in your pool.

hi,
The electronics after a sensor wouldnt be too much of a problem.
I'm not sure what type of chlorine gas sensor would be available.

I think calibration would be problem.

 

[rjvh]

the systems we sell the most (about 95%) are saltwater chlorinator systems

the HCL systems that we install are systems that maesure and dose the chlorine with a dosing pump

if there are still electrodes involved in producing chlorine that would not make sense to me
i think that the electrodes are just for measuring purpose

Robert-Jan

 

[gerharddvs]

I have just heard of so many people that got fed up with the salt-water thing and switched back to dry chlorine cause it wasn't working properly.
The risk is that if salt doesn't work U have pool full of salt lol
The salt electrodes are also a ridiculous price and the don't last very long

No I can guarantee U that those electrodes are part of the process cause U need electrolyses to get the gas of the HCL.(unless they add another chemical to react with HCL?) The difference is that U don't need those special electrodes like with salt and I think it uses less current (that's why the electrodes might be smaller)

 

[rjvh]

At the moment I just repair 2 chlorinaters (salt water)

the saltwater chlorinators are not perfect but far more fool proof and less critical than any other system

The electrodes are expencive in my opinion but should last minimum about 7000 working ours and I have seen electrodes that do double

of course if you abuse the system than everything has a shorter life span

all other systems i know of work with dossing pums but not always measuring systems to control the dosing

ometimes it is just switch the dosing pump on at a certain rate while the pool pump is running and find out with trail and error (measureing with strips)

Robert-Jan

 

[gerharddvs]

The problem is that the cost of those electrodes (maybe once a year) make up for the money U save on dry chlorine and U still have to add dry chlorine (less) when using the salt-water system cause like U said it's not perfect.
My conclusion is that there is no maintenance free pool system (unless you have a pool boy) and if someone could invent a cost effective one, they would make a lot of money...

 

[rjvh]

How big is your pool and how much hours do you run your pool pumps???

What is your climate and how warm/cold is the pool water

Robert-Jan

 

[Pommie]

I don't understand your reluctance to have a salt water pool. Mine is salt water but the amount is so small that you can barely taste it. My chlorinator is 4 years old and no where near worn out and it produces 40g of chlorine per hour. In summer I need it on 8 hours per day to keep the (active) chlorine level correct. Thats 320g of chlorine. One Liter of muriatic acid (35% HCL) contains approx 320g of chlorine and so I would need this amount per day. Where do you think this chlorine goes? In my pool it recombines with the Na+ ions to become salt again, in a pool that just has chlorine it will leach calcium from the concrete or metal ions from steps, filters etc.

I think you have confused what dry chlorine is. I suspect that what you are calling dry chlorine is calcium hypochlorite combined with cyanuric acid. I use Ca(ClO)2 occasionally - normally after I have neglected to maintain the pool in winter -and it is fairly expensive.

How is your pool currently setup? Can you try a friends salt pool as I suspect you haven't tried a properly maintained one or you wouldn't make the (incorrect) statements above.

Mike.
Edit, 2 replies while I typed this. Just wanted to add that my pool is pretty maintenance free. I add roughly 1L of acid every 2 weeks, an occasional bag of salt and the odd Kilo of cyanuric acid. Not many manual systems are as easy to maintain.

 

[rjvh]

the proper level of salt in a pool is about 4.5% and not more than 6% so that's less than what people put in their soup to eat

Robert-Jan

 

[gerharddvs]

Ok I'm completely open minded on this subject. Just tired of spending and spending money on the pool and it still looks terrible (cheaper to go to the gym)

So if I were to decide on salt I'd need a couple of stats.
What's the size of your pool (more or less) 50 000L or 100 000L?
Is it a fibreglass or marbilite pool?
How much salt do U have to put initially?
How regularly do U have to top-up the salt and how much do U add?
Does the salt effect the stability of your pH level?
Once stabilised and clean does black alge still form on the sides of the pool?

 

[rjvh]

OK more or less 50 cubic or 100 cubic that's already a big inbetween
A bit more accurate wouldn't hurt

I don't know what kind of pool you have you should tell me

minimum salt level recomended is 4% on weight of the water

toping up depends on how much you loose out of the pool by splashing and rain fall and how strong it have to work

you have to measure the levels of the pool and maintain a pool

Alge forms only if a pool is not balanced, flushed through and maintained

there are more causes but to jump into it now before having this OK it would be time wasting

by the way in my opinion a pool is a luxury and if you swim only a few times a month its cheaper to go to a pool, and pay some money for the usage of it than building and maintaining one yourself

Robert-Jan

 

[grim]

I used to work for a company that made large DC supplies for use at swimming pools and water treatment works specifically to create chlorine gas from brine. this is a link to our customers gear http://www.wallace-tiernan.com/mainsite/osecsystems.htm
prior to onsite chlorination they used to store the gas on site in tanks - and water treatment works weren't the most secure locations. each tank had enough chlorine in it to take out a small city. apparently.

as for salt in the pool, from what i remember of the process, the salt water tank was separate to the water supply. so very salty water in tank + electrodes = gas which was collected and injected into the water in the pool or water.

 

[gerharddvs]

I asked 50 or 100 cause any pool chemicals you bye are usually marked in intervals of 50. My pool is about 90 so U can say 100 000...

U don't have to be specific but U should have more or less an idea how quickly the salt is used (just like with dry chlorine I know after a while more or less how much I use in a month on average)

The trick is just to keep them clear once they are clear (that's why the interest in a chlorinator) and they are diluting the dry chlorine more and more these days

Yes I agree they are a luxury but once U have them there's no turning back unless U convert them into a fish pond or a garden feature

 

[Andrew Leigh]

Hi,

My pool is also about 90 000l so here goes.

You have to allow the resident chemicals in your pool to evaporate, you then add about 250kg of salt. How much salt you use is totally dependent on the ambient conditions and the power setting on the dial. I am in South Africa where it is on average reasonably warm for most the year.

In summer I run the pool (and chlorinator which is wired to the pool pump timer) for 12 hours per day and in winter for 6 hours.

I would estimate that I add about 8 X 25kg bags per annum.

One still needs to to add cyanuric as the stabiliser and one still needs to add acid as the bacterial cleanser. I use about 5l of acid per annum.

I bought the basic unit which requires weekly cleaning of the cells in a dilute solution of acid. If I bought again it would be the more expensive self cleaning unit.

I worked out that it take about 3 years to get a payback on the unit, and that excludes electricity consumption.

In my opinion the saving is not material, so why you may ask?

Comfort, the water becomes much more friendly to both your eyes and skin.
Convenience, for 7 - 10 days the unit adds chlorine without intervention.
Consitency, chlorine levels remain more even than when adding a "cup a day".
Freedom, you can push the unit to two weeks without cleaning, this is great if you are going on leave.

Unfortunately the nature of a pool is that it requires attention as you well know. Mine stays crystal clear year in and year out, with or without chlorinator / chlorine granules.

Cheers
Andrew

 

[Pommie]

Hi Andrew,

Two hundred kilos of salt per annum is a huge amount. My pool is also 90,000L and I add about 2 bags per years. The only way salt can be lost is by carry out, overflow, backwashing and other mechanical means. Do you have lots of rain that causes overflow or do frequent backwashes?

Also, are you saying you clean your chlorinator every week? I clean mine about twice per year and don't have any problems. Maybe your water is high in calcium. When we lived in a rental property a few years ago we used bore water to top up the pool and that was high in calcium and required frequent cleaning of the electrode. If your pool is high in calcium then switching to sulphuric acid (as dry sodium bisulphate) may be advisable as calcium sulphate is insoluble and should get filtered out.

Never thought I would be discussing chemistry on an electronics forum.

I concur with you on all the advantages of a salt pool.

Mike.