I found an issue with making an airlock where it wouldn't depressurise if my bases air tank was full, after getting to grips with that issue I decided to make it automated to minimise the risk of me messing up!

I'd made some brief notes to work out what actions I needed where, so I thought I might as well flesh it out and post it here.

You'll need the following items:

outer sensor
an air tight outer door
air vent - with its own oxygen tank, isolated from your conveyor grid (important)
an air tight inner door
inner sensor

its a shame there isn't a smaller oxygen tank, I ended up burying mine underneath the air vent, its also a pain it only has connections top and bottom...

Set up the sensor fields so that their areas are inside the air lock leaving part of the airlock in the centre clear of the sensor fields.

Additionally you'll need to set up some actions

air vent actions
when pressurised open inner door
when in vacuum open outer door

inner sensor actions (both for entering sensor only)
close outer door
vent depressurise off

outer sensor actions (both for entering sensor only)
close inner door
vent depressurise on

initially depressurise air lock with the inner door open to *partially* refill the oxygen tank with room air

Enjoy!