Exploring Valves for Depressurization

This past week, I’ve been researching different effects a loss of pressure has on the human body and subsequently, ways we can systematically control a pressure differential. With this, the paper I’ll be talking about today is A Systematic Technical Review of the Systems for the Continuous Positive Airway Pressure.

It essentially dives into the usage of CPAP, or continuous positive airway pressure, systems. It’s that device that allows you to keep your airways open when sleeping, mainly preventative for people who experience sleep apnea or preterm infants. 

Now, what I was mainly interested in was the different methods it uses to control pressure. The intuitive way I would say is using something called the venturi effect. It states that the volume or flow rate must stay constant within a pipe. Thus, with some more complex applications, we can manipulate the flow rate with varying levels of oxygen mixed in with the air. This allows us to control how much air goes into the patient’s lungs during a single breathing cycle. 

Another popular method the paper explored was using water PEEP valves. Essentially, you blast that gas into a water cylinder, and the depth of the water determines the pressure. So, we can control the pressure by manipulating the water level in the cylinder, corresponding to a more or less flow rate of the gas. 

The final novel method it peered into was the usage of mechanical valves. In most cases, it is not mechanical. Instead, there would be a sensor that is constantly scanning pressure levels. Depending on the preferred pressure and sensed pressure, it would send a signal to othe ther system, which releases gas, changes concentrations, etc… In the mechanical case, the valve is spring-loaded and held by pressure. Thus, the very act of reducing pressure would result in the valve releasing to bring the system back to equilibrium. In such a case, there would be no reliance on the circuity or accuracy of sensors. Rather, a property of the mechanical valve itself would allow it to control air flow. 

Now, these methods, of course, provide value in the medical space, but they also give insight into emergency response systems within the hyperloop. When designing a system that can mitigate the effects of a massive pressure differential, two big problems are figuring out a way to repressurize the chamber and then also doing it predictably. While medical systems only handle this on a smaller scale, the usage of purely mechanical valves and continuous positive airway systems seems promising.