Meeting with Controls + Structures as well today!

Penetration specifics for invasive pressure sensor

• Radius from the rotational axis of the tank should be small because when rotating, the liquid gets pushed to the edges of the tank

Specifications for the pressure sensor

• Should interface w/ the relief valve
  • nevermind the relief valve is completely mechanical, meaning that we literally only need the pressure to adjust the temperature readings from the thermocouple for scientific reasons (since PV=nRT pressure is varying in a constant rhythm so we should adjust the temperature readings by that same rhythm)
• Should keep away the LN2 – it should measure the gas pressure, not the liquid pressure
  • Especially important problem because the LN2 could flash boil and massively increase the pressure reading inside the pressure sensor
    • This isn't such a big deal because the pressure reading can't cause e.g. a false positive large venting from the pressure valve
  • During launch LN2 could get in because there's no spinning during launch and the only way LN2 is separated from gas N2 is basically just centrifugal force
    • nevermind because we can just use a filter 

Potential choices:

WIKA S-10 / S-11 Series (4-20 mA) https://www.wika.com/en-us/s_11.WIKA

Endress+Hauser Cerabar PMP75 https://www.endress.com/en/field-instruments-overview/pressure/Absolute-Gauge-Cerabar-PMP75

Keller PA-33X Series https://keller-pressure.com/en/products/pressure-transmitters/standard-pressure-transmitters/series-33x

Honeywell TruStability HSC / SSC Series https://automation.honeywell.com/us/en/products/sensing-solutions/sensors/pressure-sensors/board-mount-pressure-amplified/trustability-hsc-series-board-mount-pressure-sensor

Note that without power the pressure is still increasing so the valve (+ sensor?) should still be operable in an emergency condition

• Gave up on this? Not really feasible and this condition would basically happen only if OLIGO lost power entirely
• Actually – relief valve works w/ spring force = pressure force, completely mechanical
• Potential other idea for valves: fully controlled (will stay closed at all times), servo motor controls it → it is autonomous

Based on what Controls/Structures/Comms/etc. decides, we should change the configuration for the pressure sensor's penetrating tube. But the pressure sensor will probably be one of the above.

Questions

• numerical estimates for pressure generated, rate of pressure generated from expected RPM (20)