MTS Model 286-30 Pore Pressure Intensifier User Manual
Page 41
Operating Procedures
286.30 Pressure Intensifier
Operation
41
Procedure:
First, check that the
pressure intensifier
piston is suitably
positioned for
pressurization
operations
1. Observe the displacement signal to determine that the pressure intensifier’s
piston is in a suitable position for performing pressurizing operations.
Usually, the pressure intensifier’s piston is placed somewhere between 10%
and 20% displacement before starting pressurizing operations.
The best position is that which will allow sufficient retraction of the piston,
if needed to compensate for any thermal expansion of pore fluid, caused by
heating the triaxial cell, while also providing the piston extension required
to pressurize the pore fluid.
Re-position the piston, if
necessary
2. Perform this step only if it is necessary to reposition the pressure
intensifier’s piston, as determined by step 1. Otherwise, skip to step 3.
A.
Reduce the command applied to the pressure controller until the
pressure variable indicates approximately zero pressure.
B.
Close the Pore Fluid Input valve.
C.
Open the Intensifier Fill valve.
D.
Change the command applied to the pressure controller as required to
cause the pressure intensifier’s piston to move slowly in the desired
direction (watch the displacement variable), and while the piston is in
the desired position, close the Intensifier Fill valve.
E.
Open the Pore Fluid Input valve.
Note
Steps 3 and 4 relate to heating the triaxial cell (if applicable) and
pressurizing the pore fluid. Perform steps 3 and 4 in whatever sequence
is desired.
Important
Be familiar with the warning and cautions pertaining to heating fluid
within the triaxial cell. See
“Effects of Thermal Expansion of Pore Fluid”
Heat the triaxial cell, if
applicable
3. If the triaxial cell is to be heated, set up the temperature controller
equipment as required to bring the triaxial cell to operating temperature.
Pressurize the pore fluid
4. On the PPI’s pressure controller, perform the operations necessary to bring
triaxial cell pore pressure to test level.
Cool and depressurize
the triaxial cell
5. After the test is over, perform the operations necessary at the PPI’s pressure
controller to reduce triaxial cell pore pressure to a zero level.
6. If the triaxial cell has been heated, adjust the temperature controller
equipment to allow the triaxial cell to cool.
7. Turn off hydraulic power.
8. Close the Pore Fluid Input valve.
9. Slowly open the Pore Fluid Output valve to release any remaining pore
fluid pressure to the reservoir.