Coolant chemistry question

[Chris142]

Some of you may know that i work at a shop that specializes in heating and ac.

Our tap water is too hard to use in a cooling system so we filter it by deionization.

Our tap water is a 6.5 ph before filtering. Filtering it lowers the ph to 3.0.

Our antifreeze starts as 10.0 ph.

When i mix the 3.0 with the 10.0 i end up with a 6.5 ph.lower than it should be to properly protect a cars cooling system.

If i add baking soda to bring the waters ph up will the baking soda stay in suspension in operating temps? Any negatives to using baking soda to raise the waters ph?

 

[CT8]

Distilled water is acid as well.

 

[Benito]

PH of 3? That's very low.

Have you measured with something else to verify that is accurate?

 

[Chris142]

Yes we have test strips and an electronic tester.the distilled from the store is also 3.0 ph.

 

[Benito]

I wonder if this is why I've read manufacturers saying that tap water is ok to mix with coolant.

 

[Kira]

WOAH! pH3 for distilled or dei'ed water??? I called my sister the chemist and she was floored.

For reference I will test my tap water...my Britta water...a jug of distilled water and my own coolant with her extremely good test strips. NOTE: They make RNA molecules at her lab. She's a wet peptide synthesizer.

She also proffered that baking soda will go into solution to whatever degree then reach a point where it will dissolve no further. NOTE: Ever mix up baking soda to clean a battery and its environment and always there's some which doesn't dissolve?

She couldn't guess in a mixed system what the solubility rate would be. Kira

 

[CT8]

Originally Posted By: Benito
I wonder if this is why I've read manufacturers saying that tap water is ok to mix with coolant.
It depends on the mineral content of the water.

 

[edhackett]

I wouldn't use sodium bicarbonate. It will take quite a bit to raise the pH, and you can only get to about pH 8.4.

Sodium Hydroxide(NaOH) and Potassium Hydroxide(KOH) are the chemicals used by the manufacturer to adjust the pH in coolant.

Buy some lye(NaOH) at the hardware store and mix a 1N solution, 40 grams per liter, or about 1.4 oz per quart. It's not necessary to be exact. This will give you a solution that has a pH of 14. This solution will take less to achieve your desired pH and there is less risk of forming insoluble carbonate species from the addition of sodium bicarbonate.

The solution is much more hazardous that baking soda, so handle with care. Wear gloves and eye protection. There will be heat generated when the lye dissolves, so mix carefully and use a stainless steel container if you can. If you mix in a plastic bottle, set the bottle in a pan of water or the sink to eliminate the risk of localized melting of the plastic. Store the solution in a properly labeled plastic bottle.

Another option is to see if you can find a liquid drain cleaner that lists only lye and water as ingredients.

Add either of these in small amounts until you find out how much is needed. NaOH is a strong base and it won't take much to get to pH 8-9.

Ed

 

[doitmyself]

Chris, I am neither a chemist or water treatment specialist, but I have experience in water/fertilizer solution quality management in greenhouses. Hopefully an expert will chime in.

- First, you describe your DI system as a filter. DI is an ion exchange process more similar to a water softener than a filter. A DI system requires the ion tanks to be changed out occasionally. This makes me question what kind of water treatment system you have and/or is it even working.

- DI and distilled water are pH 7 when pure, but turn acidic exposed to air (CO2). They reach equilibrium around pH 5.5 (not 3). Even at this pH, they have VERY small buffering capacity and mixing 50/50 with coolant should NOT lower the mixture too much.

- It requires special equipment/techniques to measure the pH of DI water. It's nearly impossible in practical circumstances. Again, this brings up red flags about your knowledge of what you are trying to do (alter coolant chemistry).

- Ph meters are notorious for being bad. I.E - Do you calibrate your meter with a buffered solution before use? We use an expensive EC meter most of the time vs. numerous pH meters that we can never trust. We send treated water to a local lab for pH verification. I'm guessing your pH meter is not accurate.. If off 3 units, that would put your "DI" water at 6 and your solution at 9.5, both o.k..

In summary:

1. I would check your DI system function. A 50/50 solution of your DI/coolant should have the similar ph as store bought 50/50 or store bought distilled water/coolant mix (an easy diy test).

--UNLESS, somehow your DI system is producing a true, buffered very acidic pH 3 water somehow (battery acid getting mixed in???). Seems unlikely.

2. I would not trust your pH meter, unless you have an excellent one that requires calibration with a buffered calibration solution. The 3 reading is erroneous with a ph meter and "probably" the 6.5 is too. Just my opinion baed on your OP.

I have no experience with pH test strips for coolant, so will not cover that.


Hope this helps.

 

[Benito]

Originally Posted By: Kira
She's a wet peptide synthesizer


I know that sister's sometimes don't get on, but is there really need for that kind of language?

 

[Leo99]

When i mix the 3.0 with the 10.0 i end up with a 6.5 ph.lower than it should be to properly protect a cars cooling system.

Did you measure the pH of the final solution or are you assuming this? While the pH of purified/DI water might be low, it has very low ionic strength very little buffering capacity and its pH won't affect the pH of a buffered solution.

Purified water should have a pH of 5.0 to 7.0.

I'd mix up the coolant with your purified water and measure the pH with a freshly calibrated pH meter with pH 4 and 7 calibration buffers.

 

[kschachn]

Originally Posted By: CT8
Distilled water is acid as well.


Only in the presence of carbon dioxide. Otherwise no, and how would you measure it anyway?

 

[bvance554]

If you're testing ph of distilled water at 3.0 I think your test equipment is faulty.

 

[Chris142]

Ill take a sample to the water place down the street.but we use a battery operated ph meter,test strips and drops.all show the ph of filtered and dionized water in the 3 range and around 6.5 when mixed with coolant.

 

[Garak]

Originally Posted By: bvance554
If you're testing ph of distilled water at 3.0 I think your test equipment is faulty.

The procedure is faulty. You don't obtain the pH of distilled or deionized water with an electrical pH meter.

 

[kschachn]

Originally Posted By: Chris142
Ill take a sample to the water place down the street.but we use a battery operated ph meter,test strips and drops.all show the ph of filtered and dionized water in the 3 range and around 6.5 when mixed with coolant.


You really can't measure the pH of distilled or deionized water with anything like a normal pH meter. The concentration of H+ ions is exceedingly small and all you will get (besides a long stabilization period) is a localized an incorrect reading. If the water has been open to air for a long time it will contain dissolved CO2 which will alter the reading.

In any case, the actual concentration of H+ ions is neutralized by the coolant and the buffering can handle it with ease. But, the same buffers will also not allow a direct pH reading of a mixture of water and coolant either.

What you are trying to do is useless really, from a chemistry standpoint.

 

[kschachn]

Originally Posted By: Chris142
Our tap water is too hard to use in a cooling system so we filter it by deionization.

Our tap water is a 6.5 ph before filtering. Filtering it lowers the ph to 3.0.

Our antifreeze starts as 10.0 ph.

When i mix the 3.0 with the 10.0 i end up with a 6.5 ph.lower than it should be to properly protect a cars cooling system.

If i add baking soda to bring the waters ph up will the baking soda stay in suspension in operating temps? Any negatives to using baking soda to raise the waters ph?


A few other things. Deionization is not "filtering" and filtering, by itself will not change the pH of the water. Your mixing and attempts to read pH are misguided as coolant contains buffers to maintain a set pH within limits. Do not add baking soda to the deionized water as this will radically alter the pH, perhaps beyond the ability of the coolant to correct.

 

[Al]

Why would you not just use distilled water at $1 per gallon???

 

[nthach]

Would something like this work? http://www.seachem.com/Products/product_pages/NeutralRegulator.html

 

[SHOZ]

Add some ammonia to raise the pH.