Performing A Multipoint Surface Area Measurement; Calibration - Micromeritics FlowSorb III 2305 Operator's Manual

FlowSorb III

Performing a Multipoint Surface Area Measurement

The startup and sample preparation for multipoint analysis procedures are identi-
cal to the single-point method except that a multigas manifold is needed to facili-
tate shifting among different gas mixtures.

Calibration

Calibration should be performed at the start of each 8-hour operational period. It
is accomplished as described for single-point testing with a few exceptions.
•
Repeat the steps for each of the gas mixture used.
•
Determine a different number for each gas composition.
The gas flow rate may be temporarily increased, if desired, when shifting from
one gas composition to another to save time. Care must be taken in doing so to
prevent sample discharge from the increased flow. If you suspect this may be a
problem with your sample, you can temporarily substitute an empty sample tube.
After purging is complete, the flow must be restored to the operating level; i.e.,
the designated mark on the flowmeter and the Det zero confirmed.
The procedure described here presumes a Multigas Manifold is attached.
The FlowSorb must be properly flushed with an appropriate gas having a certi-
fied composition of, for example, approximately 5% N
1. Place the gas toggle switch on the side panel in the OPEN position, then
open the appropriate valve on the manifold.
2. Fill a 1-mL precision syringe to 1 mL with nitrogen gas:
a. Hold the needle tip immediately above the level of liquid nitrogen in the
b. Flush the syringe a few times to ensure a proper fill; wipe the needle tip
c. Lay the syringe aside (perhaps on the rubber mat of the FlowSorb) so
3. While the syringe is equilibrating, use the Flow knob to regulate the nitrogen-
helium flow through the instrument so that the flowmeter float is centered
on the marked line.
Mar 2012
cold trap Dewar. The evaporating liquid provides an atmosphere of pure
nitrogen.
free of accumulated frost
that the gas can equilibrate to room temperature.
Performing a Multipoint Surface Area Measurement
and 95% helium.
2
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