5. At 30 seconds, record the pressure as “CaCO
3
Pressure”. If the test
sample contains any dolomite, there will be a pause, then a slow, sec-
ond rise in pressure. Swirl the reaction cell and allow sufficient time for
the reaction to finish. The reaction is complete when the pressure
stops increasing. This should happen in 30 to 45 minutes. The final
pressure value is the total CaCO
3
pressure plus the dolomite pressure.
To calculate the dolomite pressure, subtract the CaCO
3
pressure (30
second reading) from the total pressure (30 - 45 minute reading).
6. Refer to the graph below to interpret the pressure readings.
7. Use the equations below to calculate the percentages of CaCO
3
and
dolomite. For values of “Slope” refer to the “Creating a Calibration
Curve” section below.
%CaCO
3
=
%Dolomite =
OFITE, 11302 Steeplecrest Dr., Houston, TX 77065 USA / Tel: 832-320-7300 / Fax: 713-880-9886 / www.ofite.com
8
(Pressure Reading, PSI) (100)
(Sample Weight) (Average Slope)
(Total Pressure - CaCO
3
Pressure) (100) (.92)
(Sample Weight) (Average Slope)
