let me apologize as this is a bit long, also not sure if it's in the right section.
So, i'm a domestic service engineer of 18 years. but only recently decide to look into regassing fridges/freezer etc. all the units will be r600a. however i am having trouble finding precise answers, maybe i am not searching with the right phrases? also i should say that i have no idea about this, which is why i'm here to learn hence the stupid and maybe obvious questions.
firstly manifold gauges. why are the ones for r600a more expensive then others like r134? are they interchangeable? or are the dials different?
i was speaking to a collage and he said that he never weighs in the gas, he feeds it in via back pressure? anyone know how that works?
what is the order from start to finish of regassing?
any do's and don't? and tips
i prefer to braze the joints as i know how to do it and to me it feels and looks a better job but again, any tips when it comes to brazing on f/f?
do the dryers (or is it dries) need to be replaced with each regass?, can they be cleaned?
and finally, i read that you can convert a r134 unit to r600a, how does that work?
any advice will be greatly received and many thanks for reading.

David