What these are for
The Survey has no interest in telling anybody that this hobby is silly. It has a great deal of interest in the fact that most of it is done with instruments nobody has read the specification for, in buildings nobody has walked round with the lights on, producing numbers nobody wrote down next to a time.
Fix those three things and the whole activity gets better, in the specific sense that what you find becomes something you can go back to. That is what these notes are about. The equipment ones say what each instrument actually measures and in what unit. The method ones are procedures. One of them is about carbon monoxide and is the most important thing on this site.
The instruments on this station are the free version of all of it — the methodology page sets out exactly what each one reads and where the measuring stops.