Water that thinks it's a Gas

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A3 - How pressure affects droplet size

Because of the dynamic nature of the Scotchmist nozzle, variances in pressure can be used to create mists having different characteristics, as described above. There is no need for high pressure because pressure has nothing to do with the size of the mist.

Systems that use high pressure can only produce mist by blasting water though tiny apertures but the Scotchmist dynamic nozzle has improved technology that does not require such high pressures.

This can be observed from the graph below left;

Graph of Pressure v Velocity / DropsizeGraph of Pressure v Velocity / Dropsize


Testing of Scotchmist nozzles for droplet size with varying pressures produced the mean figures shown below right, from which the above chart was devised.

Pressure Test Results SummaryPressure v Droplet Size Test Results Summary

Note: The Standard or ST nozzle referenced here is relevant to this discussion. The SR produces a larger droplet size and is used only for Class ‘A’ applications where larger droplets are beneficial.

Because of the dynamic nature of the nozzle, Scotchmist is able to produce any size droplet by varying the pressure of the flow. Consequently – and most importantly – Scotchmist can be configured to protect the fire type applicable to any project. It is the only system that can do this.

By varying the pressure, Scotchmist can achieve the results of low pressure systems, (<12.1 bar), medium pressure systems (<34.5bar) and high pressure systems (>34.5 bar). It is the only system able to do this.