Water, copper, brass and other stuff: The word water does not describe a
unique substance by a long ways. The water that I used to consider "good" for
our steam generators that pumped well over a million lbs of water an hour
through them might be useless for a computer chip maker or a laboratory doing
analysis. Pure water never stays pure very long, as soon as it comes in contact
with any metals it picks up ions from the metal. Where lab quality water is
involved piping and containers are either an inert plastic or glass. (But boiler
water at high temperatures will leach silicon from glass even.)
For our locomotives I would skip distilled or reverse osmosis water and stay
with soft household water.
Now boiler fittings. If you braze or solder brass bushings into a copper
boiler the brass can have the zinc leached out leaving a spongy mass of tin.
Therefore be sure to use bronze with tin content rather than plain zinc, copper
brass. Again there are all sorts of tins and bronzes as well. Among the worse
alloys for boiler work are the lower melting forms of Zamak, although there
are high tin content Zamaks that are fine for boiler work.
I have seen plenty of boilers with bronze bushings but with brass check
valves etc screwed into the bushings that seem to last for many years. But the
material that is bonded to the copper shell by a brazing alloy should be bronze
not brass.
I was using distiled or water from our R.O. unit in my boilers till I found
that the gauge glasses were clouding up and not cleanable with my handy pipe
cleaner. The purer (Is that a word?) RO water at heat was apparently etching
into the glass. So swiched to "soft water" that had gone through a single bed
softener to replace the calcium with sodium which I think will eliminate
scale build up but not attack other metals as the more pure water does.
