OFITE, 11302 Steeplecrest Dr., Houston, TX 77065 USA / Tel: 832-320-7300 / Fax: 713-880-9886 / www.ofite.com
9
Recommended Minimum Back Pressure
Test Temperature
Vapor Pressure
Minimum Back Pressure
°F
°C
psi
kPa
psi
kPa
200-299
95-149
12.1-67
84-462
100
700
300-374
150-189
67-184
462-1269
200
1400
375-399
190-199
184-247 1269-1704
275
1900
400-424
*
200-219
247-326 1704-2245
350
2500
425-450
*
220-230
326-422 2245-2912
450
3100
*For tests above 400°F, use Perfluorocarbon (FFKM) o-rings
23. Connect the bottom pressure hose to the back pressure receiver (if it is
not already connected). Make sure the needle valve on the back pressure
receiver is closed.
24. Unscrew the bottom back pressure regulators (counterclockwise) to make
sure both regulators are completely closed.
25. Connect a Nitrogen cylinder (at least 1,500 PSI) to the inlet on the back
of the filter press. Open the pressure release valve on the nitrogen bottle
and note the bottle pressure as registered on the gauge.
26. Keeping the valve stems closed, turn the Nitrogen ball valve on and
adjust the top and bottom regulators to the recommended
back pressure
for your test (see chart below). Make sure the bleeder valves are closed.
The upper and lower limits of the test pressure differential are determined
by the test temperature. As this temperature exceeds 212°F (100°C), the
back pressure must be increased in order to prevent vaporization of the
filtrate. The 500 PSI differential pressure must be maintained, so the top
pressure will have to be increased accordingly. The table below shows
the pressures recommended for various test temperatures.