The Item Barrel is a block added by Project Red. It is used to hold a large number of a singular item, totaling 128 stacks of 64.
Right-clicking on the Item Barrel allows the player to store the item in their hand. The barrel will display the item's icon, name, and amount on the side.
After that any double right-clicking on the barrel, no matter what the player is presently holding, will store all identical items from the player's inventory at once. This makes barrels useful for emptying clutter (e.g., Cobblestone) out of the player's inventory.
Items can be removed from the barrel once stored by left-clicking. The barrel's sides are non-interactive to automated extraction, though its top will accept items, and its bottom will extract them.
Using Importers To Extract Items
To extract items from a barrel in a controlled way and using a minimal setup, attach either an Item Importer or Filtered Importer to the bottom of the barrel (shown in Fig. 1). Attach a lever to the side of the importer and toggle it to cause the importer to extract items and eject them downward where the player can pick them up. Item Importers will extract a single item per pull, and Filtered Importers will extract a whole stack per pull.
It should be noted that the importer must be oriented correctly for this to work, with its output (the smaller of two openings) facing downward. Use a Screwdriver to rotate the importer. The importer does not snap to faces like the Hopper, but will change in orientation depending on what direction the player is looking in as they place it.
Adding Pressure Tubes
Fig. 2 exhibits a basic sorting setup utilizing the Pressure tube setup provided by ProjectRed. It involves the usage of four components: pressure tubes (similar to BuildCraft pipes), importers (such as the Item Importer or Filtered Importer), a Chest to serve as the original inventory, and Barrels as destination inventories (shown in Fig. 2).
- The starting inventory is the place where the player can offload items for sorting. This can and probably should be a normal chest.
- Place an adjoining importer to extract items from the chest. Make sure the importer is oriented properly; Its input side is the larger of two openings, and should be attached to the chest. Place a pressure tube to its output side.
- Until the system is complete, no items will appear in the pressure tubes. Set up some means of delivering a redstone pulse to the importer, whether it is by repeatedly pulling a lever, creating a Redstone Clock, or using the Timer. Items will not be transported even with a redstone pulse at this point.
- Set up an array of barrels. Ensure there is one barrel for every type of item that is to be sorted.
- Lay pressure tubes from the output of the importer up to the tops of all of the barrels. The pressure tubes should attach to the tops of the barrels if done correctly.
- Once the barrels are attached and the importer is receiving redstone pulses, items should flow through the system and into the barrels which will keep them neatly sorted.
Barrels, and in fact all possible destination inventories, supply a sort of 'vacuum' that the pressure tubes require for operation. If there is space in some destination inventory, importers will deploy items into the tubes. If there is no available destination inventory, no items will be deployed. Therefore, should this system ever run out of barrels, the importer can become stuck with whatever item it sucked up last. The chest may then appear to be filled with sortable items for which barrels clearly exist, but the system will not introduce anything into the pressure tubes because the importer is holding onto something for which there exists no vacuum pressure. This can be rectified by supplying a chest at the end of the setup for catching miscellaneous items, adding more barrels, or breaking the importer and placing back into the system once the offending item has been removed.