Analysis - Micromeritics FlowSorb III 2305 Operator's Manual

FlowSorb III
15. Inject the gas at a moderate rate. Withdraw the needle when the syringe is
completely discharged.
After approximately one minute (five minutes for Long Path), the Thresh-
old light begins to flash and the indicator starts to accumulate surface area
information. When the Threshold light ceases to flash for 15 to 20 seconds
(approximately after three minutes), the accumulation may be considered
complete. Completeness may be confirmed by pressing the DET. pushbutton;
it should be 0.02 or less.
16. Use the Calibrate knob to set the surface area value (S); this is the number
shown on the instrument display when Surface Area is depressed (refer to
equation (7) of Appendix A).
The surface area value is 2.84 when room temperature is approximately
22 °C, atmospheric pressure is near 760 mmHg, and a gas composition of
30% N
erably for conditions different from the above.
The FlowSorb III is now calibrated. Confirmation of calibration is established as
deemed necessary by making repeat injections. Reproducibility should be within
± 0.02 units on the display meter.

Analysis

Materials with unknown characteristics are best tested with the multiplier set on
x1. Only samples having less than 3.5 m
tested with a setting of x10 and then only when the sample is a slow desorber
(perhaps due to long or tortuous passageways within the sample itself). Using the
x10 setting for excessively large surface area samples may overload the signal
processing circuit and result in some error. Should this occur, a high-pitched tone
will be heard above the normal clicking sound. Select the x1 or x10 scale and
the Short or Long Path as appropriate for the sample (and as employed during
calibration).
1. When adequately degassed, transfer the sample from the Degas position to
the Test position.
A small amount of air is introduced during the transfer process. Press Det so
that the display reveals the passage through the system of this air pulse (oc-
curring within a minute or so after sample transfer). When the display re-
turns to within 0.02 of zero, press the Surface Area and the Clear SA
Display pushbuttons to clear the display.
If desired, you may start degassing another sample after transferring the
current sample to the Test position.
Mar 2012
Performing a Single-Point Surface Area Measurement
and 70% He is being used. The surface area value can vary consid-
2
2
of surface area are ever advantageously
3-7