I have a starter HF 90 Amp-AC, 120 Volt, Flux Cored Welder (Chicago Electric). I am wondering if there is any safety issue if I turn the unit on its side for operation?

I have a table with a shelf that is about 10 inches below the work surface and it would be ideal if I can lay the unit on its side so it will fit on the shelf.

Is there any reason why the unit needs to be upright during operation?