They say you learn something new everyday.

anyone who has set up track TIG torches, or orbital welders will know that more often than not you need a back purge and trailing gas too.  There are store bought solutions, but very often you find they are too wide, small, long, short etc, not to mention spendy. The other option is to make something from what you have around the shop everything from cardboard and duct tape, to aluminum tape or simple manifolds made out of drilled pipe. The problem is often times the gas diffusion is spotty, and people begin stuffing steel wool, or metal mesh into holes to try to smooth things out and make their own "gas lens".

Today I learned an "old-dog" trick that worked just as well as any store bought trailing gas, or back purge system I've seen in fact I would have to say better than some.

sintered metal plate about 0.100" thick.

We made a rectangle box form with 5 sides out of normal scrap stainless and the last side out of sintered metal (don't ask me the composition).   A normal fitting was welded on.

It worked perfect! not a hint of discoloration, very even uniform flow and low turbulence. Sintered metal is very porous in those thicknesses and this creates thousands of evenly placed holes that you can't get with a manifold or steel wool, or wire mesh. a seal welded shape allows you to keep oxygen out and even pressure throughout the chamber.

No pictures or I'd be finding a new job, but to the untrained eye it looks like a solid box and fabs up just the same

Happy welding