Flow Rate and Spray Angle

Droplet Size Basics

The spray pattern of a nozzle is made up of many droplets of varying sizes. Droplet size is the diameter of an individual spray droplet and measured in microns (micrometers) often notated with the symbol µ. One micron equals 0.001 mm(0.0000394"); there are 25,400 microns in one inch. For example, the diameter of a human hair is about 100 microns.

Adjusting the Droplets Size

Controlling the droplet size in spraying system is a critical requirement in many industries and applications, with the main methods including adjustments the nozzle type, operating parameters, and liquid properties. Here are some of the main methods:

Operating Pressure and Rated Pressure

Pressure in fluid mechanics is a very central and fundamental concept that describes the normal force per unit area exerted by a fluid (liquid or gas). Understanding pressure and its properties is essential for analyzing fluid behavior.

Main Factors Affecting Spray

All the data relating to our nozzles contained in our catalog are based on spraying water at standard temperatures. When spraying liquids other than water, performance is likely to be different. The following presentation describes how various liquid properties and operating conditions affect performance.

Nozzle Discharge Coefficient K-factor

Spray nozzles are designed to produce certain spray characteristics, most notable of which is the relationship between fluid flow rate and inlet pressure. In attempting to gain some commonality between various manufacturers, styles and capacities, it became readily accepted by the fire protection industry to use the nozzle discharge coefficient (or K-factor) for system design.

Low-pressure, Medium-pressure and High-pressure

In water mist systems, the industry generally classifies systems into three categories—low-pressure, medium-pressure, and high-pressure—based on operating pressure (MPa).

Misting System and Fogging System

Misting systems and fogging systems are both types of high-pressure atomization systems. Internationally, there is no standardized classification of misting and fogging systems based on pressure levels. The core differences between the two lie primarily in droplet size, application objectives, and technical implementation methods, rather than simply in pressure values. Although high pressure is often used to achieve finer atomization, the terms "misting" and "fogging" are determined more by the final atomization state and the application scenario.