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SVT 20
Spinning
Drop Video Tensiometer
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Description:
Optical special instrument to measurement of small to ultra low
interface tension.
For the software-controlled measurement and analysis of
- the static,
time and temperature dependent interfacial tensions
according to the spinning drop and oscillating spinning drop
method
- the
2D-/3D-extensional relaxation visco-elastic liquids and
membrane encapsulated liquids drops by variation the
rotational speed
- the yield
point of liquid crystalline and paste like materials
- the
dispersive and polar parts of liquids of surface and
interfacial tension with error limits
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Equipment:
The SVT 20 consists of
the basic instrument with the following technical equipment:
- precision capillary
system powered by an electronic brushless DC motor for different
capillary diameters
- electronic tilting
table for the capillary block, software-controlled tilt and
horizontal shift, automatically adjustable for the exact centering
of drop in the optical observational axis
- software-controlled
speed regulation to perform rotational speed jumps and sinusoidal
speed variations for relaxational measurements
- video measuring
system with high-resolution CCD-camera and high-performance frame
grabber
- high-performance
six-fold power zoom lens with an integrated continuous fine focus
and adjustable observed angle
- controlled
stroboscopic LED illumination with coupled triggering of the video
system, droplet evaluation in different rotational positions
- graphic display for
the indication the current speed, the stroboscopic angle, the
temperature and other operating status
- standard measuring
capillary with a diameter of 12.7 mm, 6.3 mm and 3.3 mm, made of
boro-silicate glass; optionally made of of quartz glass for
ultraviolet polymerization (encapsulation) of drops
- calibration to
adjustment of optical deformation by cylinder lens effect the
Spinning Drop capillary
Features of
performance:
The 32-bit
software SVT 20 developed for Windows NT/2000/XP offers by various
expansion steps:
- the time dependent
speed control and the regulation the capillary view shift and tilt
- the acquisition and
evaluation of video sequences for the analysis of fast running
relaxational oscillations and expansions of the drop
- the calculation of
the interfacial tension from the shape of rotating drops (Spinning
Drop) according to the Young-Laplace equation up to 200 mN/m and
according to the modified Vonnegut-approximation for elongated drops
for very small interfacial tensions (to 10-6 mN/m)
- determination of
relaxational moduli, yield points and other rheological parameters
of visco-elastic and visco-plastic liquids
- the calculation
dispersive and polar parts of liquids from the surface and
interfacial tension measurements with error limits
- a transformation of
acquired movies into AVI- and MPEG-files; software controlled
adjustment of picture recording and evaluation rate at
long-time tests (for example to the automatic identification by
state of equilibrium)
- statistical
evaluations (SPC) with calculation of average, standard deviation,
control on deviation of upper and lower limits, histograms etc.
- access and
administration of a liquid data base with currently 170 liquid
entries
Technical Data:
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Relational
speed |
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0 …
20.000 U/min;
rotational speed jumps: max. ± 2.000 U/(min¡Ps); oscillation
frequency: 0.005 … 50 Hz at minimum speed 3.000 U/min |
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Capillary
diameter |
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12,7 mm
(optional 3.3 and 6.3 mm) |
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Range
of interfacial tension |
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1·10-6 …
2·102 mN/m |
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Optics |
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Six-fold
zoom lens (0.7 … 4.5-fold magnification) with integrated
fine focus (± 6 mm) and high light transmitting capacity CCD-camera
with a resolution up to max. 768 x 576 pixels;
Field of view (FOV): 1.75 x 1.4 … 11.7 x 9 mm;
Optical distortion: < 0.05 % |
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Video
system |
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High-performance
image processing system with 132 MBytes/s data transfer rate
(compatible to European standard CCIR and US standard RS-170);
Up to 50 images/s variable digitizing speed (60 images/s
with RS-170) |
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Measuring
methods |
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Spinning
Drop method
Oscillating Spinning Drop method |
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Temperature
measurement and -range |
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2 Pt100
input for -60 … 450° C (1 Pt100 optional), 0,1 K
resolution; 1/3 DIN IEC 751 (±0.03 %), class B |
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Size
of device (L x W x H) |
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50 x
350 x 350 mm |
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Weight |
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35 kg
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Power
supply |
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100 … 240 VAC;
50 … 60 Hz; 450 VA
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Alternative/Supplementary
units and accessories |
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Manual and electrical
single dosing units; interfacial tension standards; dosing
needles; syringes; PTFE-tubes; complete PC systems
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