This is a sign from the Vertical Test Stand No. 1 (VTS-1) of the Santa Susana Field Laboratory of Rocketdyne, Santa Susana Mountains, California. VTS-1 was an important site used by Rocketdyne and its predecessor from the 1950s to test the U.S.'s first large-scale liquid propellant rocket engines, starting with the Redstone missile engine.
Judging from the words "Oxygen" and "Alcohol," this sign dates from the late 1940's to early 1950's when the first large-scale liquid-fuel rocket engines tested here, like the one for the Redstone missile that used these propellants.
This object was donated in 1996 to the Smithsonian by Rocketdyne.
Gift of Rockwell International Corporation, Rocketdyne Division.