How does the air device in chemistry labs work?

There are 2 basic air systems in labs: pressurized air for hand equipment tools and evacuation air for the air hoods,
Usually the pressurized air comes from a 1 to 10 hp pump located some distance away from the lab. Typically all the hand tools are limited to 40 psi, 3 bar, since anything above 80 psi can accidentally inject dirt into skin.
The air handler pump for the hood evacuation air vacuum is usually located on the roof. The air from the lab hood is put through a scrubber before venting it to atmosphere. They are high flow, but low pressure.
Some labs also have extremely high pressure stands for tests that need to be performed at 3000, or 4000 psi, 300 bar. That is produced by a special 4 stage pump that provides high pressure but low flow. Those pumps scare me.