Why Priority Splitters Matter
A priority splitter matters when one belt route must keep running while another route can wait. Community discussion indicates that a priority splitter sends its preferred output first and only uses the other output when the preferred route is backed up. This makes it useful for protecting an important production line from overflow behavior.
The current 1.0 wiki guidance does not publish a complete specification for every automation component. Treat the practical behavior below as community-reported context, then confirm ports, arrows, and routing in your current build before committing to a large layout.
An alchemy factory priority splitter is most useful after you have already separated mixed items with a Filter Splitter. Filtering handles item selection; priority routing helps decide which downstream destination should receive items first.
| Situation | Community-reported priority splitter use | Result to verify in-game |
|---|---|---|
| One output is essential | Assign the essential route as the priority output | Important route receives items before overflow |
| Secondary output can wait | Use it as an overflow route | It receives items when the priority route backs up |
| Mixed rotten-log outputs | Filter mushrooms and planks first | Priority routing can be added after filtering |
| Exact fractional removal | Use regular splits to get close to a fraction | Priority behavior may be better for overflow control |
How the Priority Behavior Helps
A Steam discussion about removing part of a full belt describes the core reason players reach for priority splitters. A player wanted to remove approximately 12% from a black-powder belt while keeping the original route useful. Regular split attempts could send more than the intended amount to the side route once the main line backed up.
One reply states that priority splitters use one output until it is completely backed up. In practical terms, this suggests a priority splitter is not primarily a precise percentage tool. It is a routing tool for deciding which destination should be supplied first.
Use that distinction when planning a belt:
- Use ordinary splits when you need an approximate proportional division.
- Use a priority splitter when one destination should be protected.
- Give the lower-priority route enough capacity to act as overflow when needed.
- Check what happens when the preferred destination is full.
The same discussion provides a space-heavy alternative for an approximate 12.5% extraction: split a belt in half, split one half again, then split that branch again. Portions can be fed back into the main line, leaving an approximate side branch. That approach may help before priority splitters are available, but it does not solve every backup-routing problem.
| Routing goal | Reported approach | Limitation |
|---|---|---|
| Protect a main belt | Priority splitter with main route prioritized | Confirm which port is priority in the live interface |
| Remove about half | One standard split | Changes if downstream belts back up |
| Remove about one quarter | Split a 50% branch again | Requires more space |
| Remove about 12.5% | Split a 25% branch again and feed the other half back | Approximate and layout-heavy |
| Handle overflow | Lower-priority output | Only receives items under the reported backup condition |
Priority Splitters and Filtered Lines
Filter Splitters are the clearer tool when a belt contains different items. Community guides describe selecting one item in the splitter menu. That filtered item exits through the highlighted output, while every other item exits through the remaining output.
For rotten logs, the reported mixed outputs are mushrooms and planks. The recommended automation pattern is to send mushrooms toward an assembler for advanced fertilizer while routing planks toward a useful consumer, storage, or disposal.
This is where priority routing can complement filtering. First, separate the items. Then decide whether one downstream path deserves priority. For example, a player may want the route serving an important process to receive its materials before a secondary route takes overflow.
Do not assume that a priority splitter replaces a Filter Splitter. The supplied sources discuss them as different tools:
| Device | Reported job | Important behavior |
|---|---|---|
| Filter Splitter | Separates one selected item from mixed output | Selected item uses the highlighted output |
| Priority Splitter | Prioritizes one output route | Reported to use the other output when the first is backed up |
| Priority Merger | Prioritizes one input | Community feedback says its input order is fixed |
| Standard splitter | Divides a belt | Can be chained for approximate fractions |
A practical sequence is:
- Run the mixed output into a Filter Splitter.
- Select the item that needs its own destination.
- Keep both filtered and non-filtered outputs able to move.
- Add priority routing only where one destination should be served before another.
- Test the line with storage boxes before attaching it to a larger factory.
The filter guides repeatedly warn that a blocked output can stop the entire Filter Splitter. That makes downstream consumption important even when the item is only a byproduct. If planks stop moving, mushrooms can stop too.
Layout Checks and Common Problems
Before relying on a priority layout, inspect the direction of every device and belt. One Filter Splitter guide notes that the highlighted, often called yellow, output can be vertical or horizontal depending on orientation. It recommends rotating the splitter with the T key and using lab stands or lifts where a vertical output needs access.
Priority Splitter community feedback also raises a usability concern: players describe output and input order as fixed. One suggestion asks for an interaction that would swap which output is prioritized, with a clearer visual indicator on the splitter itself. Another commenter says fixed priority order can require convoluted layouts.
That means orientation should be part of the first test, not an afterthought. If your preferred route points the wrong way, rerouting may be necessary rather than simply changing the port assignment.
| Check | What to look for | Why it matters |
|---|---|---|
| Device orientation | Correct input and output directions | The desired port may be vertical or horizontal |
| Priority indicator | Arrow or other live-game indicator | Community reports found the arrows potentially confusing |
| Filter selection | Correct item chosen in the menu | Filtering requires explicit item selection |
| Priority destination | A route that can accept items | Protects the intended production route |
| Overflow destination | Storage, use, or disposal | Prevents the secondary route from becoming a permanent dead end |
| Backups | Test with a full downstream belt | Reveals whether routing behaves as intended |
For filtered rotten-log lines, the reported safe destinations for planks include furnaces, quicklime or plant-ash chains, storage, and trash. The right choice depends on what your current factory can consume. A storage box may be useful during testing, but it still needs to be cleared or it becomes another blockage.
Avoid connecting both outputs of a Filter Splitter into the same belt. One guide specifically advises against it. Keep the routes visually distinct until you have verified that each destination can continue operating.
FAQ
What is an alchemy factory priority splitter for?
An alchemy factory priority splitter is used to protect one output route over another. Community reports say the non-priority output is used when the priority output is completely backed up.
Can a priority splitter remove exactly 12% of a belt?
The supplied community discussion says exact 12% is probably not achievable with this approach. Regular chained splits can create an approximate 12.5% branch, but the layout is space-intensive and backup behavior can complicate it.
Should I use a Filter Splitter before a priority splitter?
Use a Filter Splitter first when you need to separate a chosen item from mixed output. Afterward, priority routing can help determine which downstream route receives items first.
Why did my filtered line stop?
A reported cause is a blocked output. Both Filter Splitter outputs must remain clear; if one side backs up, the splitter can stop moving items.
Can I swap a priority splitter’s output order?
Community feedback describes priority splitter and merger order as fixed and requests an option to swap it. Verify current behavior and available controls in your live game interface.