Multi-Block: Must be in bottom two layers to output liquid.
The Iron Tank Valve is a block from the Railcraft mod. This block is used in the construction of the Iron Tank multiblock structure, a liquid storage device. The Iron Tank Valve is the block used to output liquids from the tank to another inventory. This block can be dyed using 8 Iron Tank Valves around a dye in a crafting table.
This block has to be placed in the bottom two layers of the structure to work properly.