Click on Droplet Test thumbnails below for enlarged views
According to NFPA 750, Standard for the Installation of Water
Mist Fire Protection Systems, 2000 Edition, drop size distribution alone
does not determine the ability of a spray to extinguish a given fire and Scotch
Mist® is an advanced system whose nozzles
produce a mist which benefits from a variety of droplet sizes.
Drop size distribution, flux density and velocity are all involved in determining the ability of a mist to extinguish a fire in a given scenario [NFPA 750, Cl. A-1-4.21] and Scotch Mist® Blaster nozzles have been tested to establish this criteria. The tests were conducted at Spraying Systems Co. facility in Wheaton, Illinois, USA
The nozzles were tested
in accordance with NFPA 750 Standard on Water Mist Fire protection Systems
2000 Edition and ASTM E799 which require all measurements to be carried out
at 1 metre distance. Testing included volume flux measurements and drop
size measurements at various pressures, taken at numerous locations within the
spray.
The one-component
Aerometrics PDPA instrument used in this test has a 100-mWatt Argon-Ion laser
to provide the light source. The transmitter and receiver were mounted on
a rail assembly with rotary plates. Size range was adjusted to capture
the full range of drops produced by the nozzle and, for each test point, 10,000
samples were acquired.
This illustration shows a typical
volume flux contour plot, produced using Microcal's Origin 6.0 plotting
software. The volume of water collected in each pan was measured and the
Origin software set up to generate a 25x25 matrix to provide data for the
contour plots.
The data
used for establishing Volume Flux Weighting was calculated by using Method 2 as
described in NFPA 750 and this illustration shows a typical plot.