Page 5 - Proportion-Air - QPV & MPV Proportional Pressure Control Valves
P. 5
QPV OR MPV PERFORMANCE CHARACTERISTICS
LINEARITY RESPONSE TO STEP INPUT
LINEARITY R ES P O N S E T O S T EP IN P U T
100 1 0 0
90 9 0 C o m m a n d
80 8 0 P re s s u re
Pressure [% of scale] 60 % 6 0
7 0
70
5 0
50
4 0
40
30
3 0
20
10 o 2 0
1 0
f S
0 c 0
0 1 2 3 4 5 6 7 8 9 10 a -1 0 0 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0
Command [Volts] Time [ms ] V o lu m e = 1 c u . in .
l e
This chart shows the linear characteristics of QPV or Times for QPV or MPV (0.040” valve orifice) to fill/
MPV products when given a ramp signal from 0-10 exhaust a closed chamber. Step command signal is
volts. Characteristics would be similar for 4-20 mA superimposed over pressure trace. Time is
units. determined by difference between command signal
and pressure achieved.
QPV vs. TRADITIONAL
Traditional Traditional
QPV QPV
Time No Flow Flow
When flow or leakage is present in the system, When transitioning from no flow to flow conditions,
traditional two valve I/P’s bleed down and then traditional I/P’s experience droop and lock up errors.
actuate the inlet valve to compensate. This gives The QPV or MPV features an error integrator circuit
erratic pressure and flow. The QPV or MPV opens its that proportionally opens the inlet valve to maintain
inlet valve proportionally to match the system flow, pressure as system flow changes.
resulting in steady pressure.
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