3.5BBL, approx 400L batch size. But honestly, not much changes as volumes increase, just more is automated.
Some general tips:
Get some chem and water resistant brewing shoes. I wear Birkenstocks.
You will get sprayed with beer eventually, guaranteed. Take a change of clothes to work.
Be careful of hot wort, treat it like hot sugar (i.e. carefully)
Always triple check you've released pressure before opening anything. People have died.
I personally don't drink beer while brewing, although I know some do. Instead, I drink coffee during the brew day, and beer when it's done.
If you are stepping into an assistant role, make sure you listen to the head brewer even if you have years of home brew experience. Commerical brewing is not that much different, but the specific processes are and it will take time to learn them.
Every brew house is different. Take your time to learn the equipment.
Brewing is just slow, cold, baking really. Learn the process and stick to it and you'll be fine.
I love brewing, and the first time someone tries your beer and tells you it's great is an awesome feeling. Also, when you get a call from a venue to deliver more beer because they've sold out is fantastic. 😁
Complimenting my beer wouldn't be thing - this brewery brews for small brewerys which can't grow but needs more beer. So they are renting brew capacity.
For clothes I hope that I can buy them off from my job - if it survives 72°C chrome etching bath it must survive wort.
Beer and work is big no no for me - some tasting maybe but drinking.
I will be assistant and from helping to set up different homebrew equipment and brewing with someone I learned that it feels like learning how to brew again.
I am just happy that I will be doing something that I like.
Sounds like you know what you're getting yourself in for, which is good.
I'd say make sure the clothes, especially the shoes are comfortable. You are on your feet all day long when brewing, so having comfortable footware is a must.