OFITE, 11302 Steeplecrest Dr., Houston, TX 77065 USA / Tel: 832-320-7300 / Fax: 713-880-9886 / www.ofite.com
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Collect filtrate at 10 seconds, 1 minute, 7.5 minute, and 30 minute inter
-
vals. The initial 10 second collection is precautionary in nature, as a fluid
with little filtration properties may fill up the 15 mL receiver tube almost
immediately, potentially damaging the regulator. Do not record the 10
second volume collected, but do record the volume collected at the other
time intervals. Timers pre-set to 7.5 minutes and 30 minutes are helpful.
While collecting filtrate, maintain the test temperature within ± 5°F (±3°C).
If the back pressure rises during the test, cautiously reduce the pressure
by opening the needle valve on the receiver and drawing off some of the
filtrate into the graduated cylinder.
23. After 30 minutes, the test is over. Immediately close (tighten) the top and
bottom valve stems to seal off the cell.
24. Allow a minimum of 5 minutes for the filtrate in the receiver to cool to
avoid vaporizing. Collect filtrate by opening the needle valve on the re
-
ceiver and leave it open until fluid ceases to evacuate the valve.
25. Close (Tighten) the needle valve on the receiver.
26. Turn the regulator T-screws on both the inlet and back pressure receiver
counterclockwise until the T-screw feels “loose”. This will stop the flow of
pressurized gas.
27. Release the pressure from the Inlet pressuring unit to the cell by opening
the needle valve (turn counterclockwise).
28. Release the pressure from the back (bottom) pressuring unit to the receiv
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er body by pulling outward on the knob which will open the bleeder valve.
29. Remove the top and bottom retaining pins and remove the two pressure
assemblies.
Take care to avoid touching the hot heating jacket, especially when
re-
moving the back pressure receiver.
30. Open the needle valve and drain any residual filtrate collected in the re
-
ceiver into the graduated cylinder.
31. Record the total amount of filtrate collected in the graduate cylinder by
reading from the bottom of the meniscus curve. Multiplying the amount in
milliliters by 2.
32. Remove the cell from the heating jacket after once again checking that
the valve stems are tightly closed. An optional Cell Carrying Tool (#170-
40) makes this a simple and safe operation.
DO NOT remove the heated cell using pliers or an open ended wrench at
-
tached to the valve stem. This is very dangerous and could cause serious
damage.
