Engine Coolant and Storage After Shows

[deverett]

I'm late to this discussion but some years ago, I used a central heating corrosion inhibitor in the hopper of my Scott vacuum engine.
The inhibitor was mixed with soft water and left in the hopper. The hopper is bronze and the cylinder is cast iron. This water treatment is not recommended!

Dave
The Emerald Isle

 

[rob smith]

Steam-distilled water will have some trace minerals in it due to its loosely-controlled commercial process, but it won't damage your steam iron or lead-acid battery if you use it to top them off.

De-ionized water is almost completely free of mineral contamination, but is more aggressive corrosion-wise because the missing calcium and magnesium salts are what buffer the water's pH to a near neutral 7. The de-ionization process requires two resin exchanges, one to exchange the cations (Ca & Mg for instance) for H+ (hydronium) ions and the second to exchange the anions for OH- (hydroxide) ions. during the process, the lonely H2 and OH ions instantly combine to form pure H2O (hydrogen hydroxide or pure water, something you should not consume in mass quantities).

Plain ion-exchanged water is the same thing as softened water. After softening, the only cations it contains are sodium (Na+). They are in the form of salts such as sodium carbonate converted from calcium carbonate (lime or CaCO3) for instance. In this example, the sodium carbonate is actually washing soda, a common laundry additive that makes soap "soapier" and prevents the formation of soap scum (calcium stearate). You may be disappointed to learn that calcium stearate is used as a food and cosmetic additive to provide thickening, but as they say, "waste not, want not".

Steam-distilled and de-ionized water taste oddly terrible because of the virtually total absence of taste-imparting trace minerals.

Water is one of the most complex simple compounds you'll encounter in everyday life. I hope this clarifies a few points. All of this information can be found online.

We used 100% deionized water in the boilers at the power station where I worked. Being a superheated steam and going through polishers it was a very neutral element with no corrosion properties. I guess the extreme volume and constant treatment was a very important factor. It was a known fact that if you drank half a glass of the stuff . You would die very quickly. It would pull all the "minerals" out of your body. (a little fun fact)

 

[HMEL]

Around here there is reverse osmosis water readily available, but not steam distilled. How does that compare to steam distilled or ion-exchange purified water?

If the distillation is well designed you will have pure water but most systems will give you water of high quality but not totally pure. Pure water is an acid and will and react chemically and it is called aggressive water in common language. Heat is applied to the water and the phase transformation to steam leaves the minerals behind. The steam is condensed and it have few if any salts. And for most purposes this is sufficient but other systems may require the water be treated further because some things can vaporize with the steam can be carried over.

With ion exchange you pass the water over a resin which has been treated usually with salt. The Na ion is exchanged for a heavier ion such as Ca so the water will have a mineral which will not deposit under increasing temperature. Using the exchange method you are just exchanging one ion for another.

Its well advised to become familiar with how to measure these properties and concentrations in water. These tests include Total dissolved solids, ph, conductivity. And it is important to know what properties the water must have for its use. You can add to the water various chemicals and ions to change the ph, and corrosion resistance.

Reverse osmosis uses pressure and a membrane to separate the ions. The water is forced through a membrane under pressure. The design of the membrane is critical and the Ions theoretically can not pass but the membrane can be expensive. The salts are then bled off to a waste stream. Its another way to purify water and you can use it to increase or recover the salts or chemicals such as sugar from a water source.

 

[Charles Lamont]

Peripherally, we have RO plant at the Severn Valley Railway to provide water for the loco boilers. New and freshly washed-out boilers are treated with tannin.

 

[bluejets]

Plenty of "waterless" coolants around such as used in Rotax aircraft engines etc.
Won't detail any particular brand except to say there are plenty.

 

[Steamchick]

I'm not a chemist... but brass fittings can have their zinc dissolved, and the consequential "de-zincification" makes the metal matrix crumbly like a biscuit (I have experienced this!) where residual boiler water has not drained or dried-out when a boiler has been in storage. Recently a fitting sheared at barely any torque when I tried to remove it, and when removed I could crumble some "brass residue" in my fingers! The fitting was the dead-space that had not drained... I have also had a drain screw crumble after de-zincification.
A Professor of Mechanical Engineering at college said: "Nature tries to reclaim the ores from which we extracted the metal, by the oxidation of the metal, exacerbated by electrolysis when water is present - I.E. Steel rusts..." - same principle applies to brass/zinc...?
K2