![](//vs1.manuzoid.com/store/data-gzf/b58ec5d67ce35ab101e82755a3f90e1f/2/001933777.htmlex.zip/bg5.jpg)
1Introduction
The Sample Delivery and Cleaning Unit turns your METTLER TOLEDO Density Meter DM40 / DM45 DeltaRange /
DM50 or Refractometer (RM40 / RM50) or combined with the Refractive Index Modules (DM/RX) or Density
Modules (RM/DX) into a fully automated measuring system for the quality control of liquid samples.
Such a measuring system is capable of
●
measuring series of samples as well as adjusting and checking the instrument automatically at the push of
a button.
●
detecting measuring errors automatically or ruling them out in advance:
•
The samples are pushed and not aspirated (as is often the case in other systems) into the measuring
cell. In most cases this will exclude erroneous measurements due to air bubbles.
•
The sampling nozzle is completely cleaned and dried inside and out after each measurement, depending
on the sequence settings. Sample carryover can be safely ruled out.
•
Before measurement, the samples can be stored in sealable sample vials. The vials are opened by the
Sample Delivery and Cleaning Unit only just before the measurement takes place. A change in the sam
ple's properties due to evaporation or contamination is, therefore, not possible.
•
The most frequent sources of error in measuring refractive indices and densities are air bubbles, inhomo
geneous samples, solvent residues in the system, or scattered light caused by solid particles. These are
automatically recognized by the system and the user is warned accordingly.
●
performing multiple measurements of the samples automatically, and directly displaying and printing the
mean and standard deviation of individual results.
●
preventing permanent contamination of the measuring cell. The measuring system can be rinsed automati
cally with up to two solvents: the first solvent removes the sample; the second solvent is a solvent of high
vapor pressure in order to dry the entire system. Both solvents are mixed with air and pumped through the
system at high speed. The resulting pulsating flow causes a mechanical and thus very effective cleaning.
●
fulfilling special requirements:
•
The SC unit is able to handle very highly viscous samples. The high pressure built up by the peristaltic
pump used to move the sample into the measuring cell and back into the vial makes it possible to mea
sure samples with a viscosity of up to 30'000 mPa·s.
•
The sampling speed of the SC unit may be adjusted very accurately. If small vials are used for the sam
ples it is possible to perform density or refractive index measurements of samples that are available in
small quantities only.
•
By equipping the SC unit with a highly corrosion resistant sampling nozzle made of Hastelloy (option),
the system is able to handle very aggressive samples such as concentrated hydrochloric acid.
•
The SC unit is able to handle samples which contain particulate material of a small grain size. If the grain
size exceeds 0.4 mm, however, the SC unit needs to be equipped with an external drain valve
(ME51327346).
●
returning the samples to the vial after the measurements. This setting is a must when using the heated ver
sion, to ensure that the sample doesn’t leave the heated area (risk of solidification). The built-in sample
recovery function pushes the samples back into the vials after the measurements (the shortest and quickest
way to empty the cell!).
Thus, the SC unit helps you to reduce the workload associated with measuring densities and refractive indices,
to ensure reliable results and to increase safety in the workplace.
5Introduction