Not really anything on market to add into system and detect low pressure and add some automatically, experimented with something used in hydroponics (irrigation)
where when a fluid passing through a valve suddenly stops the component can be made to trigger a valve or tap
but these operate at much much lower pressures than I need, and consequently worked initially, but failed.
I have a gauge to monitor air pressure though but at night can't read it well, so instead of all the wonderful things in my head I had to fix it
...........installed a short LED lamp alongside to illuminate it instead.
![Surprised :o](./images/smilies/icon_e_surprised.gif)
I know many of you will feel short-changed and may be exhibiting signs of disappointment at this pedestrian solution,
but it was raining and I'd already branded myself once this morning with the soldering iron