The Sherwood Scientific Laboratory Fluid Bed Dryer can be
programmed via a computer interface to step through an unlimited number of drying stages having the following parameters defined, controlled, and monitored:
Inlet air temperature
Blower motor speed
Pulse flow function (for difficult to fluidise samples)
Without a computer interface the Programmable Dryer can run one stored program of up to 18 steps, or can be used as a conventional Dryer.
Additional features of this advanced in-lab dryer technology include: Precise air flow control and Membrane sealed controls to prevent ingress of particles into the instrument.
Sherwood Fluid Bed Dryer
Dynamic Moisture Analyzer
# 650-50100200
AUTOMATED MOISTURE ANALYSIS
Dynamic moisture analysis software graphs the moisture curve while drying, including the critical moisture point where bound moisture is driven off.
Features
Dries up to 5 kg of wet solid (up to 80% mosture content, in 15 min
High air flow rate ensures rapid moisture removal at relatively low temperatures
Thorough mixing assures no wet spots remain in sample
Air cushion between particles reduces abrasion so that particle size is not altered
Can be programmed for a known moisture content, or to remove only surface moisture.(Great for tablets)
If water is added to a dry particulate sample, it is preferentially absorbed within each particle until saturation is reached., following which the moisture that is held is external to the particle.
Drying essentially reverses this process, and similarly occurs in two stages, initially removing external moisture before reducing the moisture content within the sample.
The Stage1 external moisture content removal occurs at a constant rate, depending on dryer parameters of air temperature and flow rate. The particles have very little influence on this moisture removal.
The,"Critical Moisture Point" is the point where Stage 2 begins, and the moisture from within the particle is removed. Stage 2 drying is not directly influenced by the flow rate or temperature of the air. To change the speed of Stage 2 Drying, one must reduce particle size, add alcohol, or chemically modify the particle to effect it's affinity to water.
Drying
DRYING CURVE
A drying curve is generated by measuring a samples weight loss over a period of time. The slope (rate of drying) is constant until the critical moisture point is reached.
Once the rate changes, moisture has begun to diffuse out of the particle.
The Classifier Assembly allows you to take a sample, remove fines, and classify your product by the Stokes' parameters of size, shape, and density (moisture).
With vigorous mixing by air flow, opening the valve on the sampler takes a representative sample in seconds without interrupting the drying process. By gradually increasing the air flow rate, the operator can selectively remove fines from the sample, which are the first to dry out, since it is less dense.
The Sampler serves as an effective classifier with samples having a broad range of particle size or bi-modal distribution. It is best to dry the sample before trying to classify.
The Sieve Drying Assembly is made to fit the analogue or digital Fluid Bed Dryer. Single or multiple stacked sieves having a diameter of 8 inches (or 200 mm) can be placed on the dryer and dried within 15 minutes.
Sealed Tub Assemblies are now available in 5 Ltr and 250 millilitre Glass-Tubs.
Samples having a wide (or bi-modal) distribution of particles are difficult to fluidise without getting some overflow of sample into the filter bag. Using a Sealed Tub Assembly, the top filter plate seals on a silicon '0' ring, retaining the sample in the tub. By selecting 5 micron inlet and outlet filters, we are now able to fluidise and dry down to 5 micron size particles. The filter size must be specified on ordering to ensure maximum drying capacity.
NOTE: THE FLUID BED DRYER REACHES A MAXIMUM EFFECTIVE TEMPERATURE OF 80 DEGREES CELSIUS, WHICH IS SUITABLE FOR DRYING MOST SAMPLE TYPES. IT IS NOT DESIGNED TO BE USED AS A REACTOR.
Tub assemblies are available in glass for easy viewing, or stainless steel.
Mini Tub Assemblies are used to dry multiple samples at a time.
FILTER SELECTION
Selection of an appropriate filter is based on the particle size distribution of the sample, and the flow rate requirements to dry the sample. Filter bags provide the quickest drying because of their large surface area, compared to a flat mesh screen.However, if sample fines are prone to air travel, a filter top cap would be required.
If you are unsure of which filter assembly to use, please make a note in the below form. as to the nature of the material, including beginning and ending target moistures, the particle size distribution parameters of the sample, and any MSDS Information you can provide.
In order to qualify for the performance guarantee, we may need to run tests on your sample for you, in which case we will require a completed MSDS Form before we will receive it.
TUB SELECTION
650-50135020 DMA TUB ASSEMBLY
(SCHEDULE 1) ACCESSORY PACKAGE SELECTION
650-50186500 HUMIDITY TEMPERATURE PROBE -00161290 COVER, H/T PROBE, STNLS STL
