Droplet size

[MikeFrazer]

Hi,

I'm looking for data (even approximate) on droplet sizes produced by a typical high performance airbrush like an Iwata Custom Micron. Obviously this would depend on nozzle/needle type & diameter, material viscosity and pressure. Does such data exist, eg for spraying water or even for particular inks or paints? I'm asking because I'd like to run an experiment to compare the performance of different droplet diameters on producing an even coating. None of the airbrush or nozzle manufacturers seem to refer to droplet size in their data sheets, even for standard performance. Any hints or pointers gratefully received!

Mike

 

[MikeFrazer]

Just to add, I realised these would be size distributions (or means/ranges), that would be totally fine.

 

[J000seph]

That would be interesting information to get ahold of. I would imagine most manufacturer responses would be what Olympos says. It’s secret. The only thing I’ve ever seen mildly similar were photographs of airbrush mist in front of a dark background.

 

[markjthomson]

Hi Mike, pop along and give us an intro...

 

[SiRoxx]

Hi,

I'm looking for data (even approximate) on droplet sizes produced by a typical high performance airbrush like an Iwata Custom Micron. Obviously this would depend on nozzle/needle type & diameter, material viscosity and pressure. Does such data exist, eg for spraying water or even for particular inks or paints? I'm asking because I'd like to run an experiment to compare the performance of different droplet diameters on producing an even coating. None of the airbrush or nozzle manufacturers seem to refer to droplet size in their data sheets, even for standard performance. Any hints or pointers gratefully received!

Mike

I don’t know of any data from the manufacturers. Closest I’ve seen would be then quoting a rough spray pattern width, but that wouldn’t help with droplet size.


Sent from my iPhone using Tapatalk

 

[crewchief227]

I could spray samples and bring them to the lab at my university and measure them. I will tell you though their is a difference between a .23 micron, and a .2mm HP. Even though the HP has the smaller nozzle the needle hardly protrudes as much as a Micron. Which that extra length is what I think gets the Microns to spray a finer droplet. The media has just those few extra milliseconds to get obliterated by the air stream. Here's a couple pics comparing a .2mm HP-CH next to a .23mm CM-C+2 & CM-SB2

 

[Sali]

Hum, I should talk to my friends in department of Physics to see if they have PDI (phase doppler interferometer). If there is one, I would love to find out the droplet size of my Iwata HP-CS and PS-270. However, instrumentation is one thing, I presume the droplet size of water will be different than that of ink and paint. Viscosity will greatly affect the size of the droplet but not only viscosity, the air pressure, humidity, and other factors too. Then the viscosity and surface tension a fluid changes with the vacuum generated at the tip of air regulator. Man, there are so many parameters.

 

[MikeFrazer]

Many thanks all for your replies. I realise there are a lot of variables at play here. Since my first post I've been looking at various laser based droplet size analysis tools. This one looks great: https://www.malvernpanalytical.com/en/products/product-range/spraytec, can measure 10,000 droplets per second ranging between 0.1 micron to 0.1mm in size. However, there is only one for sale second hand online currently for £23,000! Goodness knows what it costs new. PDI looks like it would do the job, I'll start to look if there is one lying around anywhere near me.

 

[crewchief227]

Many thanks all for your replies. I realise there are a lot of variables at play here. Since my first post I've been looking at various laser based droplet size analysis tools. This one looks great: https://www.malvernpanalytical.com/en/products/product-range/spraytec, can measure 10,000 droplets per second ranging between 0.1 micron to 0.1mm in size. However, there is only one for sale second hand online currently for £23,000! Goodness knows what it costs new. PDI looks like it would do the job, I'll start to look if there is one lying around anywhere near me.

Just find your local large university, and write a proposal. Can't hurt to ask, and there's always STEM majors looking for research topics