Vacuum chamber

Chambers are typically made of metals which may or may not shield applied external magnetic fields depending on wall thickness, frequency, resistivity, and permeability of the material used.

A small vacuum chamber is needed for de-airing (eliminating air bubbles) for materials prior to their setting.

Since the material may expand 4–5 times under a vacuum, the mixing container must be large enough to hold a volume of four to five times the amount of the original material that is being vacuumed to allow for the expansion; if not, it will spill over the top of the container requiring clean-up that can be avoided.

Once the vacuum reaches 29 inches (at sea level) of mercury, the material will begin to rise (resembling foam).

Though a maximum vacuum one can theoretically achieve at sea level is 29.921 inches of mercury (Hg,) this will vary significantly as altitude increases.

For example, in Denver, Colorado, at one mile (1.6 km) above sea level, it is only possible to achieve a vacuum on the mercury scale of 24.896 Hg.

"[3] [4] NASA's Space Power Facility houses the world's largest vacuum chamber.