Adding to the 50th's Speculation ... Kirby Queen & Mayor
From the May 21, 1956, edition of the VICTORIA ADVOCATE - Kirby Company 50th Anniversary marked (the feature was too large to fit into one screenshot) ...
"Sanitronic" was a word invented by Kirby's marketing department. You must always understand that marketing departments buy ALL their competitors' products, while the engineers sit around talking about how their machines are better and denigrating the competition. The copper color had already been launched on the Rainbow in 1962. The tan/beige color combo had already been launched on the Filter Queen in 1959. Kirby's two biggest competitors were selling 'sanitation'. That's why KGF40 was invented. Kirby wanted a piece of the 'purification' pie. Royal did that in the 1920's with the "Purifier" model. "Electronic Sanitation" became "Sanitronic". A meaningless word like "Purifier" or "Sanitation System".