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20.
Connect the manifold block from the dual Nitrogen manifold to the top
valve stem and lock it in place with the safety pin. Place the back pressure
receiver on the bottom valve stem and lock it in place with the safety pin.
The safety pin includes an attached lanyard. The lanyard secures the pin
and prevents it from accidentally disengaging from the valve stem and
pressure assembly. Always secure the pin with the lanyard.
21.
Connect the male end of the 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.
22.
Unscrew the regulator T-screws (counterclockwise) on the pressure mani
-
fold to make sure both regulators are completely closed.
23. Connect a Nitrogen cylinder (at least 1,500 PSI) to the center inlet on
the pressure manifold. Open the pressure release valve on the Nitrogen
bottle and note the bottle pressure as registered on the middle manifold
gauge.
24.
Keeping the valve stems closed, adjust the top and bottom regulators to
the recommended back pressure for your test (see chart below). Make
sure the ball valves and bleeder valves are all 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.
Recommended Minimum Back Pressure
Test Temperature
Vapor Pressure
Minimum Back Pressure
°F
°C
PSI
kPa
PSI
kPa
212
100
14.7
101
100
690
250
121
30
207
100
690
300
149
67
462
100
690
350
177
135
932
160
1,104
400
204
247
1,704
275
1,898
Manifold
Block
(#170-20)
Safety Pin
(#171-23-1)
Safety Pin
(#171-23-1)
Back Pressure
Receiver
(#170-11)