Build Rev 2Solenoids
The US Solid valves used in the prototype were only rated by the manufacturer (via email correspondence) at around 1 million cycles. If a 1:1 (BiPAP) rhythm is selected, the solenoids will cycle 43,200 times a day, giving them a service life of less than one month continuous duty. Furthermore, they were not specified as “oxygen cleaned,” meaning oils accumulating within the valves during production may react with oxygen causing a combustion risk. The REV2 solenoid valves were specially manufactured by Spartan Scientific for these field ventilator units (in one week! Shout out to Jim Koller for making this happen); and are rated at 20 million cycles, or about 15 months of continuous duty at 1:1 second cycling. They can also be continuously energized for any modes that might include a manifold shutdown.
REV2 offers significant improvements in solenoid valve control/ flow distribution logic due to the replacement of two digital relay timers from the prototype with a single Programmable Logic Controller (PLC). The new PLC can be programmed on a laptop computer and programming transferred to the PLC through a serial interface. More flexibility in valve control and elimination of mechanical relays to increase anticipated service life were significant improvements.
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