Nozzles for humidifying

Increasing the humidity levels can be important in a variety of environments.  The key to successful humidifying sprays is the controlled spraying of finely atomised sprays.  If too much liquid is put into the system then condensation or precipitation may occur.  If too little is put in then the desired levels of humidity will not be maintained.

General principle of humidifying systems

Humidifying systems generally only require very moderate levels of spray.  The amount of water needed to raise the humidity of a given environment will depend upon:

1- The ambient humidity level i.e. the starting point.
2- The rate at which the air in the area is exchanged with the wider atmosphere.  This will depend upon ventilation and air movements.
3- The temperature of the room. This will affect evaporation rates as well as the overall carrying capacity of the air.

In order achieve swift humidification from a spray nozzle one needs to keep the droplet size as small as possible and to distribute the water over a wide area.  This will help the small droplets evaporate into the air as quickly as possible raising the humidity level.

The rate at which water will evaporate from any system depends upon heat, wind, surface area and ambient humidity.  As humidity increases the rate of evaporation also increases as there is more water held in the air for heat to act upon.  It is this fact that humidifying systems exploit.  By increasing the level of moisture in the air one can increase the rate of removal and thus maintain a steady higher level of moisture through continual or regular spraying.  Of course, there is a limit to how 'loaded' air can be with water and once a certain level is reached condensation or precipitation will occur.

Key engineering considerations

Droplet size
When selecting nozzles for such systems one generally needs to look at low flow rate variants.  It is important to achieve very fine atomisation so that the natural evaporative forces can act swiftly on the spray.  With a very fine spray it is possible to ensure complete evaporation before there is any chance of wetting occurring.  Conversely if the wrong nozzle is selected and the droplet size is too large then the water may come into contact with surfaces prior to evaporation. 

Reach
To give the water the best chance to evaporate quickly it is best to distribute it as widely as possible within the area.  This is particularly true in areas with poor ventilation and little natural air movement. 

Nozzles

Air atomisers 

Air atomising nozzles deliver very fine droplets at low flow rates making them ideal for humidifying systems.  In addition to that the air used in the nozzle helps project the fine spray from the nozzle so that it can spread out into a large room quickly and efficiently.

These nozzles require both an air and water supply to work.  If both are available they are the ideal choice for humidification system.

Hydraulic nozzles 
If a suitable air supply is not available then standard misting nozzles can be suitable for humidification systems.  These nozzles will require higher fluid pressures to achieve a droplet size small enough to facilitate rapid evaporation, typically pressures of at least 7 bar will be needed. 

   

Further details on nozzle selection for humidifying systems can be found in the the "Key engineering considerations" sub sections of this page.  These can be accessed by the blue menu to the right hand side of this page.  Information on the different designs of spray nozzle that might be suitable for humidifying applications can be accessed by the grey menu, also to the right.

The information contained in the "Engineering considerations pages" and the "Nozzle designs" pages is summarised in the "Humidification Nozzle Selection Table" which can be accessed by clicking on the orange button, also to the right hand side of this page.