Exam question

Learn the difference between fusible plugs and burst discs and the answer will come from knowledge, not the internet, Grasshopper.

OK, sorry to be mean ... you need to think about (a) a bit more. That is why I said learn the difference between a fusible pug and a burst disc, then the answer should be obvious.

I must be getting soft in my old age ...

Since each stage of compressor discharge must have a relief valve it is fairly safe to assume that overpressure worries are addressed that way. The fusible plug is a thermal protection device, it will relieve pressure if the temperature rises enough to create the risk of igniting oil that has carried over with the air.

If this is for an oral, make sure you are clear that the burst disc is there to relieve pressure in the waterside if there is a tube failure in the air side of the cooler. Since in many installations the shell is made of cast iron, a tube failure can lead to explosive destruction with a lot of shrapnel being produced. A burst disc is normally fairly large and will safely relieve a large volume very rapidly.

No problem. It is a bit of a cliche' but there aren't any stupid questions. There are some people I wonder about sometimes though.

Though I can't speak for others I think it is safe to say most of us are happy to help with anything we have some knowledge of even though we don't always seem to have much patience with those who claim to be in a position where they really should know that the question, the way it's aked, or what asking it says about the questioner puts them in a whole different category.

Now that I've made that clear as mud, don't hesitate to ask, it helps everyone. I can't count the number of times I have been glad someone asked a question I hadn't thought of or felt silly about asking.