The Volume Median Diameter (VMD) refers to the midpoint droplet size (median), where half of the volume of spray is in droplets smaller, and half of the volume is in droplets larger than the median.

• Medium spray using VMD >294 microns Let’s Talk about Droplets and Spray Quality

In terms of the definitions above, the VMD is the first moment of a q 3 (x) (particle volume over particle size) distribution. A comprehensive explanation of the calculation including an example is given in ISO/FDIS 9276-2: Representation of results of particle size analysis ?

The VMD is the average droplet size by volume of the spray cloud. For example, a spray nozzle producing a VMD of 400 micron might actually produce a small number of droplets much larger than 400 micron and a large number of droplets smaller than 400 micron.

Coarse (or larger) droplets (VMD more than 325 microns) deposit eficiently on large, flat surfaces such as the leaves of broadleaf weeds. Insecticides, fungicides, and contact herbicides generally require smaller droplets (Chart 1) than systemic herbi-cides to …

There are two different types of drop size sampling techniques: spatial and flux (also known as temporal). The spatial technique (i.e., spatial distribution) is implied when a collection of drops occupying a given volume is sampled instantaneously.

This again is a number mean (number-volume or number weight mean) which in mathematical terms is expressed as D[3,0]. This is what is usually understood as the Volume Mean Diameter (VMD). Academics normally prefer the D[4,3] – the volume moment mean of the particle, because the number of particles is not required.

Size affects material behavior and processing across a number of industries. Operator dependent, need to wait for drying. The most common designation is micrometers or microns. When very small, in colloid region, measured in nanometers, with electron microscopes or …

Volume median diameter (VMD), a common term used when describing a spray characteristic distribution, is the droplet diameter at which half the spray volume consists of droplets of greater diameter and half consists of droplets of lesser diameter.

x10 = 16,53 µm x50 = 27,24 µm x90 = 41,80 µm SMD = 24,77 µm VMD= 28,40 µm x16 = 18,68 µm x84 = 38,33 µm x99 = 57,74 µm SV = 0,24 m²/cm³ Sm = 753,03 cm²/g 0 10 20 30 40 50 60 70 80 90 100 Cumulative distribution Q3 / % 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Distribution density q3* 0.4 0.6 0.8 1.0 2 4 6 8 10 20 40 60 80 100 200 Particle size ...