For custom, automated misting systems there are three different pressure levels that are pertinent to the many applications that can be offered.
Low pressure systems (50-90 PSI) run directly off of a water faucet coming from a building. These do not need a pump to increase the pressure. An example of this system is the misting system packages that can be bought from any large do it yourself hardware store. These are the lowest cost option but they will tend to get a person wet and not be near as effective at cooling the air as higher pressure systems.
Mid pressure systems (180-220 PSI) must increase the water pressure by use of a pump. The water comes from a water faucet or is siphoned from a tank. The primary usage is in an insect control misting system where there is a choice of insecticides or green natural options available in an effort to kill or repel these pesky bugs. Other uses include: outdoor cooling in more arid environments, commercial a/c pre-cooling and humidification in a greenhouse and dust suppression.
Example of a mid-pressure mist system