OFITE, 11302 Steeplecrest Dr., Houston, TX 77065 USA / Tel: 832-320-7300 / Fax: 713-880-9886 / www.ofite.com
11
Working Pressure
OFITE clearly stamps the working pressure of the cell assembly along with
the assembly serial number on each cell body and cell cap. These pressure
limits should never be exceeded on the pressure manifolds and fluid vol
-
umes inside the cell should strictly comply with instructions (see page 11).
However, in the past HTHP cells and caps from various manufacturers were
often not stamped, or in some cases, very old cell assemblies were stamped
“2500”. Cell assemblies with set screw secured caps should never be taken
to 2,500 PSI, under any temperature or condition.
O-ring Seals
Two sets of o-rings are included with the Filter Press. The first set is made
from Viton 75D. These o-rings are black and should be used for tests up to
400°F only. The second set is made from Viton 90D. OFITE suggests that all
o-rings (cell caps, cell bodies, and valve stem) are changed each time after
running a test of 350° F (176° C) or above.
Fluid Expansion Space
Cells should never be filled completely with fluid. Always leave some room for
the fluid to expand under temperature. This keeps the cell caps from becom
-
ing overstressed and possibly leading to a cell pressure failure or even a loss
of the cell cap completely.
Periodically check all gauges to ensure the proper pressures are in the cell,
as the pressure often increases or decreases depending upon the test proce
-
dure and conditions.
API Recommended Void Space
Fluid / Temperature
Void Space
Fluid Volume
Water-based drilling fluid. < 300°F
0.6" (1.5 cm)
138 mL
Water-based drilling fluid. > 300°F
1.5" (4.0 cm)
86 mL
Oil-based drilling fluid. < 350°F (176°C)
1" (2.5 cm)
115 mL
Oil-based drilling fluid. > 350°F (176°C)
Not Recommended-
Use 500 mL Cell
Void Space in a 1,500 PSI rated cell body
