3. OPERATION
Page 7
© 2004-2007 DH Instruments, a Fluke Company
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3.1
GENERAL OPERATING PRINCIPLES AND INFORMATION
3.1.1
OVERVIEW
See Section 1.5, Figure 5.
MPG1 is used to manually generate and adjust liquid pressure from atmosphere to 100 MPa
(15 000 psi) or 200 MPa (30 000 psi) using two valves and a variable volume. Fittings for
connecting to a device or system under test are located on the top and rear left side of the
instrument housing. A reservoir holds a supply of fluid.
3.1.2
VALVES
The RESERVOIR ISOLATION and TEST ISOLATION valves are manually operated needle valves.
The RESERVOIR ISOLATION valve isolates the reservoir from the pressurized circuit. It is
opened to fill the variable volume with fluid and to open the pressurized circuit to atmosphere
(vent).
The TEST ISOLATION valve isolates the TEST1 and TEST2 ports from the rest of the MPG1
circuit. It can be used to isolate the variable volume and reservoir from the pressurized test
system, for example, if it becomes necessary to refill the variable volume with fluid when it
reaches end of stroke. As the valve needle displaces fluid when it is operated, it can also be
used as a very fine variable volume for very fine pressure adjustment.
3.1.3
VARIABLE VOLUME (VV)
The variable volume (VV) is a piston-cylinder type screw press. Rotating the variable volume
handle, moves the piston in or out decreasing or increasing the volume and therefore
increasing or decreasing pressure.
The VV is used to generate and adjust pressure in the system to which MPG1 is connected
when the TEST ISOLATION valve is open. The torque necessary to rotate the VV handle is
proportional to the pressure in the variable volume.
Generally, the starting position of the VV when beginning to generate pressure from
atmosphere is with the piston fully retracted (handles rotated maximum CCW) so that the full
stroke of the VV is available to fill the test system and generate pressure.
During operation, if the VV runs out of stroke, the TEST ISOLATION and RESERVOIR
ISOLATION valves can be used in sequence to allow the variable volume to be refilled
without releasing the pressure on the TEST1 and TEST2 port (see Section 3.2.3).
The maximum operating pressure of the variable volume is 200 MPa (30 000 psi) in
MPG1-200M. Do not generate pressure greater than the maximum operating pressure.
