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Figure 1 Schematic Diagram of the Inlet Purge Device Measurement Principle
(1)P2A+P1a+f
As shown in the Purge Device Schematic Diagram: (RH Inlet Constant Flow Valve)
Elastic diaphragm is subjected to upward force:
(2)P3A+P2a+F
When the pressure is balanced,that is (1) = (2)
(3)P2A+P1a+f= P3A+P2a+F
Elastic diaphragm is subjected to downward force:
(4)P2-P3=(F-f)/A-(a/A)(P1-P2)
Since the flow rate is determined by the pressure on both sides of the diaphragm, P2-P3, the
following formula can be obtained by the formula in (3):
Since A>>a, (a/A) (P1-P2) is negligible, and F, f, and A are constant values, so P2-P3 is constant
value, then the flow rate will not change due to the pressure change at the inlet.
When the medium is an incompressible liquid, the RE inlet can be applied to the outlet pressure
variation. For (4), P1 is constant and P3 is changing, so P3 becomes P3+△P,P2 becomes P2+△P, so
P2-P3=C is a constant value.