Platinum, rhodium pyrometer hookup wire

[daniel_conlin3]

Identifying platinum / rhodium pyrometer hookup wire

I've recently come into possession of a fair quantity of old lab furnaces, kilns, pyrometers, temp controllers, etc. Some of the pyrometers are type R and type S and some of the wire is marked for use only with platinum / rhodium pyrometers, most of the wire is unmarked. I suspect that some of the hookup wire is in fact platinum and platinum / rhodium but I'm not certain how to positively identify it. The interesting stuff is the wire with green or gray insulation. It does melt using oxy/propane, but with difficulty and never exactly flows per se. It does retain a shiny surface after heating.

Any specific tests I could be doing to determine the makeup?

Thank you.

[nick1]

Pt thermocouple wire tends to ball up when you heat the end with oxy acet or oxy propane. The amount of Rh in the other wire is typically 10% so it scraps as platinum with most refiners.

The common alternatives are nichrome alloys but they are quite dull in comparison, not bright like the Pt wires. They are not as ductile as Pt either.

nick royall

[John_Donivan]

Identifying platinum / rhodium pyrometer hookup wire

Platinum OR an alloy of it with rhodium will heat up to a brilliant white heat inair and when it cools it will look like nothing ever happened to it. You can melt it with propane/oxygen but your eyeballs will be burned out of your head without welding goggles, before that happens. Beyond that, I don't evn know what a lab would do, in detail, to detect a rhodium alloy. Certainly there is nothing you can do in a typical shop oreven an atypical shop. That's big time assaying and refining stuff. Detecting platinum or "other" is about as far as you can go. Determining what the other is is possible, maybe.

[daniel_conlin3]

Thanks for your responses. This pretty much confirms what I already thought I knew.