Project: pressure guard

A meteor hits the habitat module, a piece of wall is gone. The corridor in front still has air. Whoever opens the door without thinking now loses the corridor too – and stands in vacuum without a helmet. The pressure guard prevents that.

The devices#

The rules#

• Underpressure: module pressure below 80 kPa. Then the door is closed and locked.
• Oxygen shortage: oxygen partial pressure below 16 kPa. The door stays usable, but there is a warning.
• On underpressure or oxygen shortage: warning light on, klaxon on, display red. Otherwise display green.
• Sensor gone: like underpressure – door closed and locked, alarm. Whoever does not know whether there is air behind it does not open.
• Once everything is fine again, the door is released. You open it yourself.

The core#

slt under press MINPRESS
snan tmp press
or under under tmp           # no sensor counts as underpressure
mul po2 press share
slt low po2 MINO2
or alarm under low

For the door it is enough to write both values on under: Open 0 and Lock 1. Without underpressure you write Lock 0 and leave Open alone – otherwise you would slam the door in the face of anyone walking through.

Milestones#

1. All fine: door free, no alarm, display green.
2. Underpressure: door closed and locked.
3. Underpressure: warning light, klaxon and red display.
4. Oxygen shortage: alarm, but the door stays free.
5. Recovery: lock and alarm disappear.
6. Sensor gone: door closed and locked, alarm.