basic chemistry questions for tegger

since tegger's sulking, i guess i need to do this myself.

1: with solute content of 200mg/l [which is very hard water indeed btw], 5 liters will give 1.000g of carbonate.

2: 1.000g over 2m^2 = 0.500g/m^2, or 0.00005g/cm^2. at a density of

2.0g/cm^3 that gives a thickness of 0.0001cm, or 1 micron.

3: at the rate of 0.0001cm/liter, you'd have to boil 3,000l [~793 gallons] of water to accumulate 0.3mm depth of carbonate scale.

it's a legitimate question to wonder where the hard "rock" that accumulates in radiators comes from. but the above hopefully illustrates that only a small proportion of it can come from using hard tap-water. instead, the majority comes from corrosion product within the engine and cooling system itself, and from decay of the antifreeze.

antifreeze contains salts and corrosion agents that protect by rapidly increasing the initial corrosion rate in the system to build up a passive layer. that passive layer exists in equilibrium with the coolant chemistry to prevent further corrosion for as long as the solution remains within its intended range. if diluted out of that range, or if other chemicals are introduced, equilibrium is upset, passivation can cease and non-passive corrosion starts again.

as to why we see a lot of it accumulate in the radiator, the solubility of a lot of these compounds increases with elevated temperatures, and decreases with decreasing temperature. just like the solubility of salt or sugar in water increases with temperature. thus we see dissolved material transported form the heat source, the engine, precipitating where it's cooler, the radiator.

You have made an error, how does it feel :)

Thanks for that detail. Confirms why I just use tap water for my radiator. It's not "hard" water here. Once while traveling I was in Gila Bend, Arizona. The tap water there reeked of something, maybe sulphur. I'd probably use distilled water there, but I'll never find out. Good. I'd add that minerals deposit without boiling, as seen in galvanized pipe, especially at joints. I surmise because the water slows and changes direction there. Placers essentially. But as you've pointed out, the amount of matter that can precipitate from "normal" tap water is practically insignificant.

Also add I never had a radiator clog or lose heat transfer capability to the point I noticed it, and I don't bother changing coolant except every 5 years, when I do hoses and thermostat. That's for my "highway" cars. So that's about 50k miles. I've driven my "local" cars up to 13 years without touching the coolant at all. Never change brake fluid either, and never had to replace a caliper or MC. These are Chevys. Not recommending anything, just saying.

--Vic

i dunno - how does it feel to be hiding behind mommy's skirts by not substantiating your allegation?

it's not so much flow, it's more that there's all kinds of things like precipitation nucleation going on there.

right. you can see huge precipitation in domestic water pipes. after decades of use and countless thousands of gallons of water. the coolant system on your car, unless you have an untenably large leak, sees maybe a couple of liters a year.

there's no point changing hoses every 5 years. unless you've got some really low grade junk on there. most hoses are good for 10, and are not really mileage sensitive.

you've painted yourself into a corner on that one. if you find yourself on a long steep grade with a full load, you could well have a serious braking problem because fluid that old will be well out of spec for moisture content, and thus boiling point - you should change the fluid. but, while you might think yourself lucky for not having had a problem, but i guarantee you now will if you do ever change the fluid because the seals will slowly start to shrink back to their former unworn size and thus start to leak.

check out the wikipedia page for some info:

[it's one of the few wikipedia pages that doesn't suck too bad - mainly because big chinks of it are pretty much verbatim plagiarized from the bosch automotive handbook!]

refocus your hose changing energies [and money] into a regular brake fluid changing schedule. many modern vehicles will successfully gravity bleed if you're doing it yourself and aren't a shop trying to turn around as many units as possible.

No sense complicating it. Elbows, T's, and unions get clogged at 4-5 times the rate of straight pipe. That's all a plumber has to know.

I never have to add water to my cars unless there's a leak. A properly operating cooling system doesn't pop the cap.

Sure they are. They're pressurized when the car is at temp.

5 years might be excessive, but that's about the time I do it, because that's when I do a flush and change the thermostat. Just get the "feeling" it's time. I'd feel real stupid if I popped a hose while on vacation in Florida.

No way. That seems to be mostly a Honda fetish. GM has no maintenance schedule for brake fluid, and I have *never* had a brake failure. I know, I know. I've read all about how important it is to change brake fluid. So I don't tell anybody not to do it. Now I won't change mine for sure, since you told me it's too late.

--Vic

that's because they don't intend the first owner to keep the car that long, and the second owner, they couldn't care less about. [frod /invented/ that game btw - g.m. are simply copying.]

the technical necessity to change brake fluid due to its hygroscopic nature, moisture absorption and boiling point depression to below service working temperatures is incontrovertible so there is no technical reason for g.m. to disregard fluid maintenance. the reason is

100% some management m.b.a. having done the math on the cost of lawsuits being less than the cost of having dealers do maintenance. iow, customer deaths are just a financial statistic, not an ethical obstacle.

too late to save your seals, but not too late to have a braking system that can save your life - that's a couple of hours and at most a couple of hundies to replace the master cylinder well invested in my book.

Depending on how hard that water is, it can cause a lot of problems for home plumbing systems, car radiators too.About 15 years ago I had my old iron water pipes replaced with plastic plumbing.

In a 'different vein', depending on what some people eat, (fried foods/fatty foods) their plumbing (veins) gets clogged up too.Have you ever donated blood plasma before? I have, many times.Some of those people's blood plasma in the plastic containers, you can see stuff floating around in there.My blood plasma didn't have anything floating around in my blood plasma containers.If you visit a hospital clinic, they can show you some photos of what fried foods/fatty foods do to the inside of those blood veins.That crap leads to heart attacks too. cuhulin

I thought it would be more constructive for you to find your own error.

based on some of your past performances, you probably think "legitimate" is spelled wrong.

Let me try to guess what his error is. He states that the solubility of CaCO3 increases with temperature but that is not always true. It's solubility is determined by the amount of CO2 present, the higher the CO2 content the more soluble CaCO3 is but like most gases the solubility of CO2 in water decreases with temperature. Therefore we have a trade off at a certain temperature where calcium carbonate becomes less soluble with temp increase. That's why you're more likely to see scale in hot water pipes.

Engineman

but it's not an open system - you can't just buffer in and out from atmospheric.

2 errors then.