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Title

SRAD Pneumatically-Actuated Vent Valve

Description

An SRAD pneumatically-actuated vent valve, which allows better control over the state of the oxidizer tank during fill procedures than would be afforded with the permanent vent port used in previous iterations of the engine. It uses compressed air stored onboard the rocket to actuate a piston which opens and closes a vent port. The valve is normally open, and fails open when supply air pressure is insufficient. All components of this system are currently made from 6061-T6 aluminum, but the flight model may be fabricated from stainless steel for increased durability. This system has been successfully cold-flow tested using liquid CO₂ to confirm that it actuates correctly under pressure.

Photo

Key components

1. Vent Valve Body

2. Vent Valve Piston

3. Vent Valve Cap

Rated Pressures

• Pneumatic side pressure: 145 psi MAX. This is based on the highest rating on most pneumatic components, which is typically 1MPa (145psi)

• Oxidizer side pressure: 1000 psi MAX. This is based on the highest temperature Nitrous Oxide can reach when stored in the tank

Tests Done

• Seal strength tests with water as an analogue for Nitrous Oxide up to 1400psi of water: Vent Valve Water Testing - Google Sheets

• Cold Flow tests. March 21st 2020. Performed with CO₂ as an analogue for N₂O

  • Cold flow #1: Air supply at 65 psi and CO2 cylinder at ~700psi. Actuation unsuccessful

  • Cold flow #2: Air supply at 95 psi and CO2 cylinder at ~820psi. Actuation successful + hold for 2 minute duration.

• Static Fire 5: Performed with N₂O. Successful actuation with 720psi air pressure

Design Documentation

• Documentation: https://docs.google.com/spreadsheets/d/1gXsN0nkNqklEbQT71M4wr9zbHAlupa4lq0Nml6fbTjo/edit?usp=sharing

• Process: Vent Valve Design Process Doc - Google Docs

• Specifications: Vent Valve Specifications - Google Docs

• Calculations: 2020 Vent Valve Calcs - Google Sheets

• BOM: Vent Valve BOM - Google Sheets