3. OPERATION
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© 2007 DH Instruments, a Fluke Company
Figure 8.
Ready/Not Ready
in dynamic pressure control mode
3.2.2.3
STATIC CONTROL
Static control
mode is designed to set the pressure near the target value and
then interrupt active control to allow pressure to stabilize naturally within a hold
limit (Figure 9).
The advantage of this control mode is that pressure can be set and/or measured
within a defined limit of a target without interference from the pressure control
system. In a system without excessive leaks, the pressure stability achieved
may be greater than the stability with which the pressure control system can
actively control pressure. Using static control to control pressure near the
desired set point and then measuring back the stabilized pressure without
interference of the control function can allow control errors to be eliminated
completely. However, the final pressure achieved is not equal to the target value
and the time required to achieve sufficiently stable pressure is dependent on the
characteristics of the test volume and may be longer than in other modes.
During static pressure control, the hold limit is active. If the pressure goes outside of
the hold limit, pressure is readjusted to the target value. See Table 8 for default
hold limit values and Section 3.4.6 to customize the hold limit.
Figure 9.
Static pressure control operation
