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Hi all,Just got a regner lumberjack.  It runs great!  The instructions say to use distilled water mixed with 3-5% tap water.  Is this right?  I always thought anything but distilled water was a no no.  So far I've only used straight distilled water.  Anybody use a distilled tap-water mix?
Dan
 

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It seems that Regner uses brass boilers (check if yours is brass). If so, then having a few dissolved metal ions in the water makes it less likely that the zinc will be leached out of the brass.
 

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Posted By monsterhunter on 01/27/2009 2:18 AM
Hi all, Just got a regner lumberjack. It runs great! The instructions say to use distilled water mixed with 3-5% tap water. Is this right? I always thought anything but distilled water was a no no. So far I've only used straight distilled water. Anybody use a distilled tap-water mix? Dan



Well, it may have a brass boiler, but persnally, y'unnerstan, I would put nothing in in but distilled water, regardless how much it needs it daily ions or whatever. This seems to be a 'thing' of German-made steamers, and this advice to add tap-water can also be seen on Maerklin live-steam advisory notes.

My advice is to keep up the present medicine.

tac
www.ovgrs.org
 

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I use straight commercial distilled for my Willi. My conductivity meter shows Kansas City area distilled water runs about 5ppm total ion content, or 2% of the tap water reading. So there is a small ion content already. If the zinc leaching theory is correct, then the ions added would need to be zinc ions to be any help. Zinc solubility should not be suppressed by the common calcium, magnesium, and sodium ions. However, even tiny amounts of ammonia or its derivatives, like chloramine, the usual source of disinfecting chlorine, does dissolve copper and brass. The local distilled water labels indicate they use ozone disinfection, not chloramine. Big industrial boilers use special additives to neutralize any ammonia. But then they also will have a water quality lab and seldom use brass or copper boilers anyway.
 

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Yesterday I spent the afternoon at Linda Hall Library searching for everything they had about brass and copper boiler corrosion. For brass boilers the main problem is called dezincification. This is caused by the alloy being formed of microscopic grains that contain high and low amounts of zinc. Immerse the brass in a conductive solution and the zinc/copper boundaries form millions of tiny batteries. The zinc and copper are dissolved, with the copper then being redeposited in place forming the characteristic red spongy deposits. The zinc stays in solution and will eventually form white crystals of various zinc compounds on the boiler surfaces.

To minimize the problem, brass alloys should contain at least 85% copper. Various trace metals are also used to minimize attack. The attack is promoted by both acid and alkaline conditions as well as dissolved oxygen. The various references to attack in soft water seem to be actually caused by the low buffer capacity of pure water which can allow the pH to swing to the acid side. The best pH is in a narrow range around 7.5 to 8.0, or very slightly alkaline. In our size boilers, special boiler additives are too hard to manage properly. The only other action which might help is to use freshly boiled water to fill the boilers. This will drive the oxygen and some of the carbon dioxide out of solution. A quick, short boil is all that is needed. This de-aeration will also happen naturally during steamup since we have sealed pressure vessels.


Adding small amounts of tap water will eventually concentrate the calcium and magnesium salts to form boiler scale which greatly reduces heat transfer. Blowdown or periodic draining will prevent this buildup. To halt all attack the boiler must be completely drained and dried, not easy to do with the tiny fill openings.


Acid and oxygen attack also occur in copper boilers but to a lesser extent. Both copper and brass boilers can be quickly corroded by the use of dissimilar metals on wetted surfaces. Adding a steel or brass fitting to a copper boiler can set up an instant battery.


The brass cylinders are safe because only pure water is present and an oiled surface is also protective.



In practice, I intend to continue using commercial distilled water. I do test each new gallon with a conductivity meter for purity. An inexpensive aquarium pH test kit also checks the pH. If necessary, a tiny amount of alkali will bring the pH to 7.5 - 8.0. A reading of about 6.5 is normal for pure water from dissolved carbon dioxide in the air and not cause for alarm.
 

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Regner writes that the slightly acidous character of pure distilled water is the reason, and that adding thathat small amount tapwater will make it "neutral".


I'm not sure if Regner (and the boilers he supplies Maerklin with) are brass or copper. I think Regner uses silver-solder for fittings. But what about plain tinn / lead soft-solders, how sensitive to acid are they? 
 

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Both Willi and Vincent look like brass boilers & all fittings are brass. Anything lower melting than silver solder, which is apparently actually brazing, not simple soldering, is going to be big trouble. Silver brazing joints should melt at temperatures way above operating temps.

Their assumption that a small amount of tap water will bring the distilled back to neutral might sort of work, if your city uses chloramine, not ozone. But the scale forming calcium, magnesium and other impurities are no help at all. Also, some city supplies are naturally on the acid side, so no help there at all. I found vague references that some cities in the British Isles have acid or acid-forming water, but no details.
 

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"Tap water" varies considerably from locale to locale and from season to season or even day to day. Depends also on whether the house has a softener too. It would be nice to know Regner's water's analysis to know whether our own water is the same or it could actually make things worse.
 

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A quick test of the tap water neutralizing theory failed here in Kansas City. Most of the metro gets their water from Kansas City, Missouri Water Dept. A jug of local grocery store distilled water started out at pH 6.0 with a Total Dissolved Solids (TDS) reading of just under 5ppm. City water runs nearly pH 9.0 and TDS of 250ppm. Adding the recommended maximum 5% tap water brought the distilled water to pH 6.3 and TDS 15ppm. So the water remained on the acid side, but now it has some hardness to eventually form boiler scale.

If we start out with this 5% tap water added mix in our boiler, and run the boiler down to 20% of capacity, then the water remaining is now concentrated by a factor of 5 or now 25% of the hardness of the tap water. If there is no blowdown or draining, the next fill doubles the concentration. After four fills, the water remaining is now at 5% x 5 x 4 or 100% tap water. If you live in a hard water area, scale is now forming in your boiler.

Your water supply will depend on the local geology. If you live in the middle of alkali flats, you will have alkaline ground water. Sedimentary rocks, especially limestone or marble, will produce slightly alkaline hard water. Granite will tend to produce an aggressive acid water due to mineral acids such as sulphuric acid being present. Ditto around old mine tailings. Peat bogs and marshes will also be acidic, but from organic humic acids - not as strong as the mineral acids, but boiling tends to strengthen them. Your local water company may then soften the water or not. They may or may not adjust the pH. They may use chloramine disinfectant which tends to the weak alkaline side, or use ozone which has little pH effect. Good water system practice is to stay slightly on the alkaline side to minimize lead poisoning from old soldered fittings and, yes, solid lead pipes.


So, adding small amounts of tap water to distilled will probably not produce a neutral pH because the tap water is not a strong enough alkali. It is likely to lead to boiler scale.


Using straight distilled water will minimize the chances of scale formation. It is slightly acid. But that acidity is from carbonic acid generated from the CO2 in the air. Vigorous agitation or boiling tends to quickly drive the CO2 out of solution resulting in a boiler water near neutral.

For the truly paranoid, you can make a high purity, low hardness, slightly alkaline, boiler feed water by obtaining a weak caustic solution of about 0.1 molar sodium or potassium hydroxide or carbonate. Adding 10-20 drops of this weak caustic to a gallon of distilled should bring it to about pH 8.0, slightly alkaline, but not too alkaline. Any resulting salts are highly soluble, not scale forming, nor will they generate acid when boiled. Periodic blowdown or draining is still good engineering practice.



As Science Officer Spock would say, "The probability of Chief Engineer Scott damaging the wee bairns from distilled water is vanishingly small compared to the risks from accidental overheating or impact with unforgiving solid objects."

It seems that Scotty also likes miniature steam engines.
 

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This is an interesting discussion. I have one of those Marklin BR18's and the instructions are the same recommending a small mix with tap water. Most of my others engines are Accucraft, Aster, Pearse or Catatonk. My question to all the experts is this. I usually leave my boilers full of water(distilled) ready for the next steamup. Is this harmful over the long term? Should I be draining them after running? Most of these engines get run at least once a month and some weekly. I never blow them down or empty them other than what is used running. Thanks.
 

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In order to obtain a good "dry layup" all the moisture would need to be removed. I was thinking about using a aquarium air pump to do this.
 

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With clean water in the boiler, sealed up, room temperature, several days with water in the boiler should be no problem. Long term shutdown, careful drying is necessary.
 
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