REAL-TIME, HIGH SPEED HIGH CONCENTRATIONSPRAY DROPLET SIZER

Malvern Spraytec For real time, high speed measurements of highconcentration liquid droplets in sprays, aerosols and inhalers.

Particle size measurement using laser diffraction has been developed and applied byMalvern Instruments for more than 30 years.Malvern’s Mastersizer is the industry standard fora range of laboratory measurements.Malvern’s Spraytec is built around the sameprinciple, but adapted for the specific needs forthe characterization of sprays and aerosols.

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Malvern’s Spraytec combines the proventechnique of laser diffraction particlecharacterization with patented high concentrationdata inversion routines for the analysis of sprayswith high or rapidly changing concentrations.Spray measurement requires an accurate, high-speed measurement device immune to materialcharacteristics.The Malvern Spraytec providesscientists with the ability to obtain precisemeasurement data from all types of sprays.

Sealed to prevent moisture, dust and gas ingress,the robust instrument housing allows operators toeasily access the droplet stream in a wide varietyof experimental or production environments.

Aerosol and spray researchers face challenges every day. Malvern’s Spraytec makes meeting these challenges easier.

Aerospace Composite Technologies Ltd,Icing Research Wind Tunnel

High Speed Measurements up to 2500Hzwith Flexible Triggering Options

Spraytec offers real time spraymeasurement at speeds of up to2500Hz, giving a time resolution of one measurement every 400microseconds.The measurementspeed is software configurable.Measurements can consist of singledetector scans or averages ofmultiple scans, to provide the mostaccurate data possible.The hightemporal resolution offered by the Spraytec reveals fine temporalfluctuations in spray patterns and allows measurement of shortduration sprays such as metereddose inhalers, dry powder inhalersand fuel sprays, that are missed by

slower systems.

Multiple measurement triggersare provided, making it easy tosynchronize measurementswith spray actuation in anyexperiment configuration.Since sprays can be of very

short duration, random, orintermittent at high repetition

rates, correct triggering of themeasurement of such sprays isimportant to ensure that data iscaptured consistently. Malvern’sSpraytec offers four triggeringmodes; allowing measurements to be triggered manually, throughautomatic spray detection based on changes in light transmission,

via low concentration triggeringbased on detection of a predefinedlight scattering signature, or byexternal triggering with a signalfrom another device.

Spraytec Software – “Frame-by-Frame”Analysis, Time History Utility, Data Filtering

Malvern’s Spraytec software providesa user-friendly interface to monitorand control all data reduction anddisplay functions.The time historyutility enables a “frame-by-frame”inspection of a spray sequence, thatshows exactly how the droplet sizedistribution evolves throughout thetime frame in question.

Fig 1 shows a time history of a fuelspray of 0.444 seconds in duration.During this period, 112 separatemeasurements were made.

A variety of statistical displaysenables quick data analysis andcomprehension, without beingforced to export data into additional analysis programs.

The software also allows operatorsto include or exclude measurementsequences, allowing analysis to avoidperiods between sprays, outside ofacceptable obscuration or signallimits, or otherwise undesired.

Fig 2 shows a time history file for a 15-millisecond puff from a drypowder inhaler.The controlvariables shown are the Dv50, theDv10 and the Dv90 as well as the transmission.

Fig 1 Fig 2

High Concentration Measurement Capability – Allows the Measurement of Sprays at Obscurations of up to 95%

The phenomenon known as“multiple scattering” occurs whenthe light scattered by droplets inthe spray encounters furtherdroplets and is further scattered atlarger angles, before reaching thedetector. Uncorrected, this leads toa substantial overstatement of thefine droplets in the distribution.

A patented multiple scatteringalgorithm, automatically correctsfor this change in signal and allows successful measurements in extremely high concentrationswith light obscuration as high as95% (5% transmission).

The multiple scattering algorithmhas been validated by measuringprogressively higher concentrationsof a suspension of AluminumOxide.The corrected curve at 95% obscuration (5% transmission)over-plots the measurementobtained at 16% obscuration (84% transmission).

Fit for Purpose – Flexible, Robust,and Simple in Design

Sprays are wet, messy and canoccupy large volumes. How does Spraytec deal with thesefundamental problems?

Large clearances betweentransmitter and receiver modulesaccommodate sprays with largecone angles and minimizecontamination of the optics.Sealed transmitter and receivermodules and air-purgeable opticsfurther minimize contamination by spray products.Transmitter andreceiver modules are designed sothat mounting on custom rigs is achievable with minimalengineering effort.

A range of laser diameters is avail-able to improve spatial resolutionwhen characterizing extremely brief highly concentrated sprays,for example, fuel injection nozzles.

For applications that requireadditional protection against dust,water or flammable materials a rangeof NEMA enclosures is available.

A choice of optical units areavailable (see specifications foroptions) which allows the user toselect the best balance betweenminimum measurable droplet sizeand working distance.The softwarealso includes an imaging correctionfacility that allows the correction ofdata, where, for any reason, thedroplets being measured are outsidethe working distance of the lens.

Specifications

Applications

Malvern’s Spraytec instruments are used in a wide range of industries:

SPEC

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Optical Unit

Measurement Principle Mie ScatteringLight Source Laser Diode 670nmLaser Beam Diameter 10mm, 6mm and 3mm 1/e2

Measurement Rate 1 to 2500Hz (giving 1 measurement every 400 microseconds)Concentration Range Sprays with obscurations from 2% to 95%Accuracy 3% (using RS-3 reference standard reticle)Precision 0.5% (using RS-3 reference standard reticle)Droplet Size Range Maximum Working Distance Lens Focal Length

0.5µm to 200µm 150mm 100mm1.0µm to 400µm 300mm 200mm2.25µm to 850µm 675mm 450mmAir Purge Optics can be purged with clean air to protect them from contamination during

measurement. Minimum supply of 2ft3 min-1 must be completely oil and water freeSealing Standards Non-NEMA enclosures, water and dust proof to NEMA 4/12. Hazardous gases

NEMA 7, NEC Class 1 Groups A, B, C and D

Software and Data Processing

Minimum Specification of PC Pentium II 300MHz processor, 32Mbytes RAM, 3Gbyte hard disc and CD–ROMScreen resolution VGA 800x600 (SVGA 1024x768 is recommended)

Operating System Windows NT™ 4.0 and aboveData Analysis Model-independent analysis gives droplet size distribution

Patented Multiple Scattering Algorithm for operation at high concentrations (US Patent No. 5,619,324)Statistical analysis for QA/QC

Data Display User configurable SPC charting and report formatsTime History Display “Frame-by-frame” data display Data Export Direct to Excel or similar spreadsheet in text file format (ASCII)

Accessories

XYZ aerosol mounting unit Accurate positioning in X, Y and Z axes is accomplished using this mount

Weights and Dimensions

Module WeightsTransmitter module 5.75kgReceiver module 7.50kg

Bench OptionsShort Bench 300mm spray gap. Height of laser above bench 250mmLong Bench 500mm spray gap. Height of laser above bench 250mm

Custom Benches are available at extra cost depending on material, finish and size

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Industry Application

Engineering Design and optimisation of spray nozzels – for the pharmaceutical, food,cosmetic, paint, chemical, fire protection, power generation, agriculture and lubrication industries

Pharmaceutical Formulation, development and testing of MDI’s, DPI’s and nasal spraysAutomotive Engineering Diesel and Fuel injection studies, airbag developmentAerospace Engineeing Simulation of extreme climates

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Setting standards of excellence – our commitment to you

The people at Malvern Instruments areinnovators, not just in product design, but

in every area of business. Malvern hasinvested to achieve ISO9001 with TickIt

accreditation – we accept nothing short ofexcellence.As many of our systems are

used in the toughest regulatory markets,product validation and developmenttraceability are key commitments to

our customers.

Malvern trained specialists are available inmore than 50 countries to assist with

applications development and to advise onand analyze ‘difficult’ samples. Our

laboratory facilities in North and SouthAmerica, Europe and Asia routinely run

thousands of customer samples every year.

Our innovative approach to customerservice is illustrated by the development of

after-sales remote diagnostics.Malvern Instruments’ service specialists can

access and control systems via standardtelephone lines in order to minimize down

time and reduce cost.

In many industries particle size analysis hasbecome a key QC parameter.The need toobtain data as close to the line as possible,

and to react quickly to that data, isincreasingly important. Malvern’s in-process

division applies its expertise to meet thischallenge through the development and

production of on-line particlecharacterization systems for

in-process applications.

With laboratory systems and in-processproducts, Malvern Instruments meets your

particle analysis needs from Lab to Line.

For a full description of all Malvern Instruments’ products and services

please contact your nearest office.

Malvern Instruments makes

every effort to ensure that this document

is correct. However, due to Malvern

Instruments’ policy of continual product

development we are unable to guarantee the

accuracy of this, or any other document

after the date of publication.We therefore

disclaim all liability for any changes,

errors or omissions after the date of

this publication. Des

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