what type of water?

[Keith S]

A guy on the "Mamod" forum, who is a chemist, did an interesting little experiment. I really don't feel like trying to find the link, since it will take me all day. You see, on that forum there are also frequent and interminable discussions about this issue, even more in fact since those guys are often dealing with engines that are 100 years old and they hope to keep going for another 100... anyway, he exposed pieces of brass cut from the same sheet to different kinds of water (including his tap water, vapour distilled, and de-ionized) for a certain period of time and then photographed them in an electron microscope. Believe it or not, the brass that had been in de-ionized water actually did show some surface changes that looked a bit like etching. I can not attempt to interpret this result, for all I know it was just very, very clean. Some other types of water showed mineral deposits and whatnot. It was a clever experiment that he took a great deal of time to do, just for the purpose of trying to get to the bottom of this issue. I believe this guy's conclusion was that he was going to mix a little tap water into his de-ionized water.

I'm sorry I can't include more details, but I personally don't really care. I steam my engines VERY infrequently, and I feel that de-ionized water in a copper boiler won't hurt it one bit. I have a traction engine with a brass boiler, and I steam it about once every two years at most and the rest of the time it is kept bone-dry with the whistle open and the safety-valve unscrewed.

[Keith S]

OK, I found the link after not too much effort. Here it is:

http://modelsteam.myfreeforum.org/ftopi ... ectron.php

Pretty clever experiment. We can all agree Kevin put a lot of work into it.

[ace]

OK, I found the link after not too much effort. Here it is:

http://modelsteam.myfreeforum.org/ftopi ... ectron.php

Pretty clever experiment. We can all agree Kevin put a lot of work into it.

The End...

[rebelego]

OK, I found the link after not too much effort. Here it is:

http://modelsteam.myfreeforum.org/ftopi ... ectron.php

Pretty clever experiment. We can all agree Kevin put a lot of work into it.

Great. Thanks!

Anyway, I think you should know your tap water very well before using it as suggested in that article.

[Boustrophedon]

The tap water at school has destroyed 5 Mamod boilers and one Wilesco . Some of the Mamods look almost new as if they had only been steamed a few times. My Mamod is 50 years old and has only been steamed with tap water and is fine. The water at school is very acid about pH 5.

I also suspect that the fuel tablets leave a corrosive deposit, I only use meths burners at home.

Brass reacts very differently to pure copper and both are different again to the steel used in full size.

With copper boilers the brass fittings and stainless superheaters will probably more vulnerable to corrosion than the boiler.

[Keith S]

My Dad told me after my Grandfather gave me a little Mamod, that the soot from the fuel pellets was corrosive and should be cleaned periodically. I don't know if this is true but I've always believed it, well because it's a thing my Dad said..

[GTB]

The water at school is very acid about pH 5.

That is very soft for tapwater. I guess you don't have to descale kettles very often in that area. The pH is about the same as distilled water, or DI water.

I also suspect that the fuel tablets leave a corrosive deposit, I only use meths burners at home.

ESBIT tablets are mostly hexamine and I'm reasonably sure Mamod tablets are the same. The ESBIT tablet msds states the combustion products contain ammonia and NOx, both of which are soluble in water and can corrode copper.

Graeme

[Boustrophedon]

Distilled water should be neutral at pH7?

[GTB]

Distilled water should be neutral at pH7?

Theoretically, but in practice it is exposed to air, so it absorbs CO2 which forms carbonic acid and once at equilibrium the pH will be about 5.

Graeme

[DVT Dweller]

OK, I found the link after not too much effort. Here it is:

http://modelsteam.myfreeforum.org/ftopi ... ectron.php

Pretty clever experiment. We can all agree Kevin put a lot of work into it.

Very impressive work and a lot of effort has obviously gone into that. Very appropriate for those with old mamod and locos built upto the mid 80's. However are more modern dragons built by roundhouse and accucraft have copper boilers. So results would be different I assume?

[Keith S]

I assume so. I've only ever heard of people being worried about de-ionized water with regard to its effect on brass. If they have copper boilers then they worry about brass fittings. I'm personally willing to bet that the brass fittings on my Roundhouse locomotive will last longer than I do.

[Clinkard]

I have had an Accucraft Countess from new (about three years), it has only had a very little local tap water (hard) initially, and then self-distilled water (from tap water) used in it, and generally very little use compared to many.

Having a little burner trouble last Sept, I set about cleaning the jet and inadvertently broke the gauge-glass. On trying to replace it I found the bottom fitting leaking and further investigation proved it to have de-zinced, indeed it collapsed on final removal. I take the point about distilled water gathering CO from the atmosphere but I know my water storage (well sealed). De-zincing can happen even to the careful.