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Part C: LabTec™ Dispensing Applications
1.0 Weight Ratio Dispensing: General Information
The Weight Ratio Dispensing mode is designed for automated weighing and diluting of samples.
In this operational mode, the LabTec™ is connected to an electronic, top-loading scale.
The LabTec™ will tare the scale after the sample container has been placed onto the scale.
The sample is then placed into the container and the sample weight is stored and displayed by
the LabTec™. The diluent is automatically dispensed by the LabTec™ based on a user-defined
sample to diluent weight ratio. For example, if the sample weight happens to be 10.00 grams and
the user-selected weight ratio is 9.00, then the LabTec™ will dispense 90.00 grams of diluent to
provide 10-fold dilution by weight. Regardless of the sample weight, the desired dilution ratio will
be maintained. Only an approximate sample weight needs to be placed into the sample container.
1.1 Sterile Dispensing:
When sterile liquids need to be dispensed, two (2) pump dispensing options are available:
First, the LabTec™ CP-200 mounted with the 1082 peristaltic
pump head is the
method of choice when dispensing pre-sterilized solutions. Utilizing
autoclavable
Silicone pump tubing and 0.2 μm filter cartridge, sterility of the liquid can be
readily
maintained during the dispensing process. The sterilized solution comes only in
contact with the sterilized #24 Silicone pump tubing.
Second, the LabTec™ MP320 mounted with a Magnetic Gear Pump Head
(Model 201) and used
together with a 0.2 μm filter cartridge, allows in-line filter sterilization of
solutions while
dispensing. This method avoids the need for pre-sterilizing, i.e. autoclaving of
solutions; a
significant savings both in labor and energy. Here the magnetic gear pump head is
recommended because of the high output capacity (3.5 liters per minute).
In-line filter sterilization is recommended when large batch volumes of sterile solutions are
needed, e.g. dilution of combined samples in Salmonella bacteriological testing which typically
require 2-4 liters of sterile diluent per sample. By using a SciLog
®
SciPres
®
Pressure Sensor,
you can monitor the backpressure generated as the filter becomes plugged, and set a
user
definable limit to either Alarm Only (audible beep) or Pump Stop (stops pump and beeps).
In-line filter sterilization is also recommended for large volume dispensing applications in
media kitchens. Utilizing large surface area filtration devices, i.e Parker PROPOR SG
DEMICAP P/N: ZESGB-020-HH-PS3, 1500 to 2000 liters of media can be dispensed
with a single
filter cartridge. However, the actual filtration capacity is heavily dependent on the
particulate
load of the solution to be filtered. Your Parker Territory Manager
can help identify the filter
suited for your application.
When using the LabTec™ with a 201 magnet gear pump head, you need to install an in-line
check valve (P/N: 400-530) preferably at the pump discharge side.
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