This page (and several links) is going to walk through assembling a high pressure pump for misting.
There are two pump options, diaphragm pump or positive displacement pump. First will discuss the diaphragm pump.
Diaphragm pumps are an option for small outdoor misting system. They are typically not used in commercial misting applications. They are a good options to consider because they can be much less expensive than positive displacement pumps.
Diaphragm pumps can produce up to 150 psi of water pressure. This is enough pressure to mist small orifice nozzles down to 0.15mm. However, 0.15mm nozzles will not produce much mist at 150 psi. 0.20mm or 0.30mm nozzles are more appropriate.
Control of a diaphragm pump is easier than positive displacement pumps. A diaphragm pump can run dry (no water) for a much longer period of time than positive displacement pump. Water is the source of cooling for each pump but the heat build up from friction is much less with diaphragm pumps. This heat build up will eventually destroy each pump. With a positive displacement pump this will happen quite quickly, within a minute or so. Diaphragm pumps is a much longer period of time, maybe hours.
One of the key parts when using a diaphragm pump is a bladder tank. This is a storage tank for holding a small amount of high pressure water. The diaphragm pump fills this tank up to 150 psi water pressure and then shuts off. Water then goes from the bladder tank to the misting nozzles. As the pressure reduces in the tank the pump eventually comes back on, typically around 120 psi. This tanks is your storage of high pressure water. It is also key to to keep your pump from short cycling.
Badder Tank must be rated for at least 150 psi.
A 150 psi rated badder tank is needed. Not something you can get at HomeDepot. Generally the Badder Tanks a HomeDepot are rated for 100 psi. I recommend American Wheatley HVAC Producrt. They have 150 psi rated badder tanks. Eather the BPT-002 or the BPT-005. Google search brings you right there.