Factorio Forums

If you place the pipe below the assembly machine, it won`t feed the machine until you place some other material.
If you place the pipe above it, the machine will be fed with the content of the pipe immediately.

This doesn`t break any functionality, but is a little inconsistent and confusing, I thought the pipe wasn`t able to feed the machine at all before testing thoroughly.

That's because the assembling machine is inactive and turned itself off knowing it can't possibly work because it's lacking items for the recipe it needs to work.

It's a performance optimization that doesn't actually impact the factory except when you're looking at the fluid numbers

So when a pipe is placed north of a factory the factory is not inactive? Seems like a very specific optimisation when the inactive status of a machine is affected by its orientation.

BenSeidel wrote:So when a pipe is placed north of a factory the factory is not inactive? Seems like a very specific optimisation when the inactive status of a machine is affected by its orientation.

No, pipe flow flows from top->down and left->right so the pipes above the machine flow into the machine where the pipes below require the machine to move the fluid from the pipe into it. When the machine is inactive it doesn't pull the fluids.