Malvern Instruments Spraytec, User Manual

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Introduction
This chapter describes the full process of making a measurement, explaining at
each stage how the Spraytec works. It begins with a summary of what the Spraytec
does, then covers the following:
.
Preparing the spray and the instrument.
.
Designing a Standard Operating Procedure (SOP).
.
Capturing the scattering pattern – the principles of Spraytec operation.
.
Calculating the particle size.
.
Displaying results – the importance of volume-based results and how pa-
rameters are derived.
.
General issues – experiments, records and the use of measurement files.
The Spraytec summarised
The Spraytec instrument measures the size of particles in a spray. Specifically, it
measures the distribution of different sizes within a spray. The measurement
process involves the following steps:
.
A spray is prepared and delivered using an appropriate spray delivery device
or accessory.
.
The spray is delivered between the two functional modules of the instru-
ment, the Transmitter and Receiver modules.
.
The Transmitter uses a He-Ne (Helium-Neon) laser to produce a laser
beam that passes through the spray delivered to the measurement zone.
.
Detecting optics in the Receiver module detect the light diffraction pattern
produced by the spray, converting the light detected into electrical signals.
The signals are processed by analogue and digital electronics boards, and
passed to the analysis software.
The light diffraction pattern is analysed using an appropriate scattering
model to calculate the spray size distribution.
.
The software displays the results in a number of forms, including histo-
grams, result-under plot and result-over plot, etc.
.
The user further processes the data as required, re-analysing records, aver-
aging records, comparing sprays using overlays, etc.
.
Saved data is exported as required for use and further analysis elsewhere.
The use of Standard Operating Procedures (SOPs) ensures that results are as
objective and reproducible as possible.
C H A P T E R 2
S p r a y t e c
P a g e 2 . 1