How to Choose Misting Nozzles

Types of Nozzles for Misting Systems

Misting nozzles for outdoor cooling systems produce a fine mist that evaporates quickly and cools the surrounding air. This is different from other nozzles that may create heavy mists or streams of water or other liquids.

Misting Nozzle Mechanisms

Pressure-based nozzles for misting systems can operate at a range of water pressures, from as low as 100 psi (7 bar) to thousands of psi (bar), depending on the exact model of nozzles. They can withstand a wide variety of water qualities.

Impeller-based nozzles are less common, but still very effective. They use a spiral-shaped interior to break up the water into droplets. They typically work at lower water pressures under 100 psi (7 bar). They tend to clog more easily, so water should be thoroughly filtered or treated to remove minerals.

Misting nozzles differ from other nozzles in a few key ways:

• Flow Rate: Misting system nozzles have a lower flow rate compared to other nozzles that produce a steady stream of water.
• Spray Pattern: Mist system nozzles produce a fine mist with droplets that are smaller in size and more evenly dispersed than other kinds of nozzles.
• Material: These nozzles use materials that can hold up to outdoor environments. Stainless steel and brass are commonly used materials.
• Pressure: Nozzles for outdoor cooling systems generally operate at lower water pressures compared to other misting systems. This creates a more gentle and consistent mist that is better suited for outdoor cooling.

Misting Nozzle Materials

Misting system nozzles are made from a variety of materials, but some of the most common materials include:

• Stainless steel is often used in misting systems due to its durability and corrosion-resistance, but it can be difficult to install and expensive compared to other materials.
• Brass is also commonly used due to its resistant to corrosion. It is easy to machine, which can help keep its cost down.
• Plastic nozzles are a cost-effective option. They are lightweight, easy to install, and resistant to corrosion. They are not durable enough for high-pressure systems and work best with low- and mid- pressure systems. They are not as durable as other materials and may become brittle and crack over time. They are inexpensive enough to replace often, but shards may dislodge and clog the system.
• Nickel-plated brass is similar to brass in terms of durability and resistance to corrosion, but the added nickel plating provides an extra layer of protection against rust. It’s sometimes used as housing for stainless steel orifices.
• Ceramic nozzles are very expensive and less commonly used. They are highly resistant to corrosion and are used in high-pressure misting systems. Although they are durable, they are fragile and can break if not handled correctly.

Misting Nozzle Options

Drain valves automatically drain the system each time it is turned off. This helps prevent nozzles plugging up due to calcium buildup, meaning much less nozzle and system cleaning needed. This is especially helpful for large systems or hard to reach nozzles.

Adjustable angle / swivel – Some mist nozzles can rotate or swivel to direct the spray in varying directions. These are helpful with fine-tuning the spray.

Anti drip nozzles and adapters close each time the system is turned off to prevent dripping from the nozzles. Dripping increases mineral buildup on your nozzles. Mist nozzle dripping may not be a problem if the water drips onto concrete or dirt. It could be a problem if it drips onto wood or machinery or guests.

Cleanable –Most nozzles must be removed from the lines in order to clean. But the interior of cleanable nozzles can be removed for cleaning and then replaced back into the exterior which stays in the lines.

Extensions – These can extend the mist of your system by as much as 18″.

Multiple orifices in one nozzle allow for spray in several direction at once.

Replacement heads allow you to replace damaged or clogged orifices without having to remove and replace the entire nozzle.

How Many Gallons per Hour Does a Misting System Use?

Flow Rate / Water Volume and Nozzle Size

The size of the mist nozzle orifice (opening) balances with your misting system’s water pressure and flow rate (amount of water) to create a cooling mist. Nozzles typically spray less water at lower pressures than at high pressures. But because the spray droplets are larger, they will not feel as cool.

In fact, certain mist nozzles will not work at all at lower water pressures. As the water pressure at the nozzle increases, the flow rate through the nozzle increases. The higher the water pressure, the smaller the nozzle opening you’ll need.

It will help to decide on the water pressure you want your system to use before selecting the mist nozzle.

The larger misting nozzles will work well with low- and medium-pressure misting systems. The smaller misting nozzles should only be used with high-pressure systems. If you select too large a nozzle for your water pressure, the pump won’t be able to send enough water through it to create a fine mist. If you select too small a nozzle, the over-supply of water through the nozzle may “over-pressure” the pump and damage it. It’s not a matter of “more is better” but of balance.

Sample Droplet Sizes

Here is a sampling of water droplet sizes based on common nozzle sizes using 1000 psi / 70 bar. Water droplet sizes are measured in “microns” (1 micron is .001mm). To give you a size reference, 100 microns is about the diameter of a human hair. The largest of these droplets is just under half that.