IV. SAMPLE ANALYSIS
Stepwise measurement instructions
1. Ensure that the unit has been switched on for at least 15 minutes for the pressure transducer
to warm up and stabilize.
2. Select the appropriate REFERENCE VOLUME for the size of sample cell by using the
toggle valves “I” and “II” according to the table printed on the unit (below the zero knob).
3. Open the "VENT" toggle and "VENT” RATE needle valves. Wait for a stable near-zero
reading.
4. Close the "VENT" toggle valve and set the display to zero.
1
5. Turn the Selector valve to “V
R
” (REF).
6. Open the “GAS FLOW IN” toggle valve, and pressurize to approximately 17 (psig) using the
"GAS FLOW IN” RATE needle valve to control the rate of pressurization. Stop the flow by
closing the “GAS FLOW IN” toggle valve.
7. Record the display reading after it has stabilized. This value is "P
1
" in Equation (8).
8. Turn the selector valve to V
C
+ V
R
(CELL).
9. Record the display reading after it has stabilized. This value is "P
2
" in Equation (8).
10. Vent the pressure slowly to prevent blowing powder out of the cell, by opening the "VENT"
toggle valve with the "VENT” RATE needle valve slightly open.
11. Use equation (8) to calculate the true sample volume and density (see Worksheet).
12. Repeat steps 4 – 11 to obtain at least three replicate measurements. Average the results.
NOTE: The pressure transducer used in this pycnometer dissipates a very slight amount of heat. Because of its extreme
sensitivity it can track the slight pressure increases associated with the heating of the gas. Accordingly, it is necessary to
take the first reading observed after the digital display stabilizes. A change of approximately 0.001 on the digital display
every 10-20 seconds is indicative of pressure increases due to heat dissipation and is normal. By taking the first reading
after the display stabilizes and then rotating the selector valve and again immediately obtaining the first stable reading,
the most accurate and rapid results will be achieved.
1 If unable to zero the display please email qc.service@quantachrome.com for assistance.
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