i'd like to make an electronically controlled version of a simple ball and spring pop off valve, like those used to relieve pressure at a certain setpoint. the setpoint is adjustable by screwing the pop off valve housing together or apart, which changes the pressure on the spring.
i see the mechanical pop off valve as a non-linear flow "diode". in the sense that if the pressure is too low to move the ball at all, it conducts almost no air, and the when it does start conducting air, the increase in pressure differential across the ball is very slight as flow increases drastically, like the increase in voltage across a diode as current increases drastically.
if you have an electrically controlled orifice, you could map the orifice size versus pressure differential at a certain flow rate, and then do the same for the pop off valve, and use the same map for both, so that the electrically controlled orifice behaves just like the mechanical pop off valve..i.e. a pressure sensor reads a pressure, and the orifice opens to provide the same flow rate you would see in the mechanical pop off valve at the same pressure. this would be an open- loop system with no feedback...
what yall think?
the benefits of this is that you could set the setpoint electronically and the system could be pretty cheap