>All the ones I've ever looked inside have had soldered brass or bronze
>movements (though brass certainly wouldn't work for ammonia).   If you
>have a gauge lying about you can open it up and see -- but I doubt there's
>anything but metal once you get into the actual gauge.  I'd be more
>concerned about hoses leading to it.

Just checked the US Gauge catalog -- theirs are all phosphor bronze for
regular, with beryllium copper or 316L stainless for specials.

david

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"