Hydrochloric Acid vs Sulphuric Acid in automated dosing

[JoyfulNoise]

I understand. The current setup doesn’t require us to poor acid at all. We buy 25kg containers and all we do is move the suction from empty container to the new container by moving the lid together with the hose (the hose goes through the lid). We have no splashes of acid.

HCl is also available in similar containers. The pump room is underground with a trapdoor. If I move the acid container outside it will be above the dosing pump level. Probably won’t work. Also it has max 8 feet of suction length by design. And it will also put the acid tank easily accessible to the kids. How much fuming should I expect from a closed lid container with the tube tightly going through the lid?

You absolutely do not want to tightly seal an HCl acid container. They need to be vented to avoid bursting. The Pentair tanks have a venting system that allows the tank to take air in to avoid a vacuum lock caused by pulling liquid out of it. I believe there is also a vent to avoid positive pressure build up. Even 10% HCl at room temperature has a vapor pressure of 1.95kPa (0.3 psi positive pressure) and so it has to be ventilated to avoid acid build up.

I don’t think HCl can work safely in your setup. Acid tanks are dangerous no matter how they are constructed and HCl vapors are very corrosive to metals. Unless you can store the tank outside, you’re safer from physical damage using sulfuric acid.

 

[fanis.merk]

You absolutely do not want to tightly seal an HCl acid container. They need to be vented to avoid bursting. The Pentair tanks have a venting system that allows the tank to take air in to avoid a vacuum lock caused by pulling liquid out of it. I believe there is also a vent to avoid positive pressure build up. Even 10% HCl at room temperature has a vapor pressure of 1.95kPa (0.3 psi positive pressure) and so it has to be ventilated to avoid acid build up.

I don’t think HCl can work safely in your setup. Acid tanks are dangerous no matter how they are constructed and HCl vapors are very corrosive to metals. Unless you can store the tank outside, you’re safer from physical damage using sulfuric acid.

The H2SO4 is sold in plastic containers, so is HCl. I cannot say that they are super airtight but they are closed by lids. We simply drill a hole in the lid and put a hose in to suck the acid. I haven’t heard any containers exploding in shops. If I drill a hole on the top of the container (in addition to the suction hole) and put a hose in and let the hose out from the trapdoor I was thinking by principle of least resistance the fumes would go that way. Do you think that would work?

 

[JoyfulNoise]

The H2SO4 is sold in plastic containers, so is HCl. I cannot say that they are super airtight but they are closed by lids. We simply drill a hole in the lid and put a hose in to suck the acid. I haven’t heard any containers exploding in shops. If I drill a hole on the top of the container (in addition to the suction hole) and put a hose in and let the hose out from the trapdoor I was thinking by principle of least resistance the fumes would go that way. Do you think that would work?

No.

HCl vapors are heavier than air. They sink and pool. Unless you have active ventilation, the vapors will just not flow against gravity.

I’m not sure what the regulation are in Turkey, but here in the US, muriatic acid containers utilize vented caps to avoid vapor build up.

 

[fanis.merk]

No.

HCl vapors are heavier than air. They sink and pool. Unless you have active ventilation, the vapors will just not flow against gravity.

I’m not sure what the regulation are in Turkey, but here in the US, muriatic acid containers utilize vented caps to avoid vapor build up.

That’s very important information about the fumes. Muriatic acid containers are very basic. You can find even in a grocery store with 5% concentration for toilet cleaning etc. If I move the tank above the peristaltic pump level do you think I can extend the length? There is a bushy banana tree where I can hide the container by running the tube for 15-20 feet.

 

[oldprophet]

There is not much feedback from people on this site who actually use automated HCl dosing. The article on this site recommends yearly hose replacement. So there actually seems to be some truth to difficulties in pumping HCl even though chemically it is a better solution. I will look into CO2 injection systems. So far never heard of them in the market but I understand how it works.

Here in SoCal every commercial pool that I've been involved with that had automatic chemical injection used hydrochloric acid, I have never seen sulfuric acid used

 

[fanis.merk]

No.

HCl vapors are heavier than air. They sink and pool. Unless you have active ventilation, the vapors will just not flow against gravity.

I’m not sure what the regulation are in Turkey, but here in the US, muriatic acid containers utilize vented caps to avoid vapor build up.

So basically the HCl vapor will start first accumulating in the container itself. As it will accumulate it will start building pressure and in your opinion even with that pressure will not be enough to beat the gravity if the rest of the container is sealed?

 

[fanis.merk]

Here in SoCal every commercial pool that I've been involved with that had automatic chemical injection used hydrochloric acid, I have never seen sulfuric acid used

That’s good to know. Where were they keeping the acid container? Open air? How do they secure the container from kids?

 

[JamesW]

Some places in Florida push the use of sulfuric acid but I don't know why.

 

[JoyfulNoise]

So basically the HCl vapor will start first accumulating in the container itself. As it will accumulate it will start building pressure and in your opinion even with that pressure will not be enough to beat the gravity if the rest of the container is sealed?

The HCl vapors will simply build up in the head space between the liquid and the top of the container. Temperature fluctuations will cause the vapor pressure to change and the container will “breath” acid vapors in and out of any opening. Your setup doesn’t really “seal” the container so vapors will move out of it.

Again, I don’t think HCl will work well for you. I have no idea how to plumb it but if your tank is higher than the pump then you need to have fail-safes in place to avoid an accidental gravity drain if ever there is a leak in the tubing. A check valve needs to be used that can hold off the force of the liquid pressure from a higher location. If the tube were to ever leak, then entire tank could drain out.

 

[fanis.merk]

The HCl vapors will simply build up in the head space between the liquid and the top of the container. Temperature fluctuations will cause the vapor pressure to change and the container will “breath” acid vapors in and out of any opening. Your setup doesn’t really “seal” the container so vapors will move out of it.

Again, I don’t think HCl will work well for you. I have no idea how to plumb it but if your tank is higher than the pump then you need to have fail-safes in place to avoid an accidental gravity drain if ever there is a leak in the tubing. A check valve needs to be used that can hold off the force of the liquid pressure from a higher location. If the tube were to ever leak, then entire tank could drain out.

I understand. It seems in Europe people seem to be tending towards Sulphuric Acid due to closed technical rooms.

pH correction Archives

pH correction products - pH minus and pH plus - for adjusting the pH value, acidity, of your swimming pool water. This can be done with powder or liquid product.

www.lifeisbetteratthepool.be

Also European Union has a well defined regulation for carrying Sulphuric Acid around but I couldn’t find one for HCl.

https://www.legislation.gov.uk/eur/2019/1148/data.pdf

 

[JoyfulNoise]

In the USA, sulfuric acid is highly regulated because it is used in the illegal manufacturing of narcotics and drugs. So it’s not available to the general public. Even with HCl, most vendors have to record who they sell it to.

 

[JamesW]

In the USA, sulfuric acid is highly regulated because it is used in the illegal manufacturing of narcotics and drugs. So it’s not available to the general public.

Non-Fuming Sulfuric Pool Acid

Non-Fuming Sulfuric Pool Acid Lowers pH level to help balance pool water to prevent long term corrosion.

villagespapools.com

sulfuric acid v muriatic acid

The fellow who owns his own, local pool store mentioned that sulfuric acid is a better way to affect pH than muriatic acid. I've not heard this before, and have always used muriatic acid. My SWG needed cleaning, and I used muriatic acid, which seem to work just fine. But he said sulfuric acid...

www.troublefreepool.com

Non-Fuming Pool Acid 1 Gallon - AAA-8626

Non-Fuming Pool Acid is a professional strength (38%) non-fuming pool acid for effective pH balance control. It will acid wash pool surfaces and will not fume the area. An effective replacement for Muriatic acid wherever a non fuming product is required. See product label for use directions

www.thepoolsupplywarehouse.com

sulfuric | Duda Diesel Alternative Energy, Chemicals & Industrial Supply Store

 

[JoyfulNoise]

Must be a Florida thing. Around here, you can’t really find sulfuric acid and, if you do, they ask you for your drivers license. Even when I buy muriatic acid, they have to see ID. I suppose you can order it online but I’d be surprised if the shipping costs were not really high … liquid acids can only be transported by truck and usually only through certain carriers that have the DOT licenses to transport HAZMATs.

 

[fanis.merk]

Must be a Florida thing. Around here, you can’t really find sulfuric acid and, if you do, they ask you for your drivers license. Even when I buy muriatic acid, they have to see ID. I suppose you can order it online but I’d be surprised if the shipping costs were not really high … liquid acids can only be transported by truck and usually only through certain carriers that have the DOT licenses to transport HAZMATs.

It seems you also have a “low fume” muriatic acid product in US. Is it a marketing gimmick or something that actually works I don’t know.

AcidBlue®, Buffered Low-Fume Muriatic Acid - 1 Gallon - Leisure Pool & Spa Supply, Inc.

AcidBlue is a buffered, low-fume replacement for standard muriatic acid. Acid Blue uses a full-strength proprietary formula that is easier to use, ship and store compared to standard muriatic acid. This product by Champion is the latest in pool chemical advancement. This low fume Muriatic Acid...

www.leisurepoolinc.com

 

[JoyfulNoise]

It seems you also have a “low fume” muriatic acid product in US. Is it a marketing gimmick or something that actually works I don’t know.

AcidBlue®, Buffered Low-Fume Muriatic Acid - 1 Gallon - Leisure Pool & Spa Supply, Inc.

AcidBlue is a buffered, low-fume replacement for standard muriatic acid. Acid Blue uses a full-strength proprietary formula that is easier to use, ship and store compared to standard muriatic acid. This product by Champion is the latest in pool chemical advancement. This low fume Muriatic Acid...

www.leisurepoolinc.com

It usually low strength (like 10%) or it contains an additive that reduces surface evaporation. Either way, not something we ever recommend using.

 

[Bperry]

Must be a Florida thing. Around here, you can’t really find sulfuric acid and, if you do, they ask you for your drivers license. Even when I buy muriatic acid, they have to see ID. I suppose you can order it online but I’d be surprised if the shipping costs were not really high … liquid acids can only be transported by truck and usually only through certain carriers that have the DOT licenses to transport HAZMATs.

Maybe that’s a state thing? I’ve never been hassled buying MA from Home Depot.

 

[JoyfulNoise]

Maybe that’s a state thing? I’ve never been hassled buying MA from Home Depot.

You’re face is plastered all over every security camera and you paid for it on a credit card … they know exactly who you are …

And, apparently I’ve been informed that you should buy it in small quantities and not my usual pallet of sulfuric acid, 15 gallon drum of hydrogen peroxide, and 60 boxes of pseudoephedrine… I guess that “sets off some alarms” …

 

[proavia]

I’ve been informed that you should buy it in small quantities and not my usual pallet of sulfuric acid, 15 gallon drum of hydrogen peroxide, and 60 boxes of pseudoephedrine… I guess that “sets off some alarms” …

Maybe it's a Tucson thing. Never had them ask in the PHX area.
Or maybe it's the green hair in your profile pic......

 

[jesse-99]

FWIW, I dose Muriatic Acid in my pool using a Stenner pump (adjustable flow rate that I can dial in, as need be). Like you (@fanis.merk ) I have high TA fill/auto-fill water of 330. So it's a massive pain to manually dose MA. You get the yo-yo effect constantly (pH goes up, manually dose, pH goes down, pH goes up, dose, pH is back down, etc.), this is especially true with high evap pools (mine has a huge surface area compared to most and I have tons of water features that cause evap as well) because your auto-filling more 300-330 TA constantly. I got sick and tired of manually dosing 3-4x per week. So that's why I did a Stenner pump for it, (injection is after my heater and after my (2) SWCG's). Furthermore, I feel it's safer (for me), and I don't have to worry about getting acid on my patio/pavers anymore either as I walked around the pool for manual dosing. My Stenner pump is outside, and I can't speak to using the acid indoors, but I would imagine, that -could- be a big concern if you're not wearing a mask and there's no ventilation in the room. When I'm outdoors, I just have to make sure the wind doesn't kick the fumes back to me, but in 3 months of filling my Stenner pump, I have never had an issue with intake of the fumes, whereas when I would manually dose, at least once a week I'd inhale some no matter how cautious I was being.

Your situation in Europe is much different than mine in the US , but for my $.02, I would never go back to manually dosing MA (I can use up to 2 gallons per week, if I'm using my water features). Open to answering questions if you have any.

 

[oldprophet]

That’s good to know. Where were they keeping the acid container? Open air? How do they secure the container from kids?

Usually in an outdoor area that would be 8,ft high fencing and a locked equipment area, as per state code