Multi-Block: Must be in bottom two layers to output liquid.
The Steel Tank Valve is a block from the Railcraft mod. This block is used in the construction of the Steel Tank, a multiblock liquid storage device. The Steel Tank Valve is the block used in outputting liquids from the Tank into other devices, such as Liquid Loaders. It can be dyed using 8 Steel Tank Valves around any dye in a crafting table.
This block has to be placed at the bottom two layers of the structure to function properly.