Fluid wagon vs Cargo wagon comparison: Transporting fluids

[Kametec]

I've been reading through various "fluid wagon vs barrels in cargo wagon" discussions recently. I couldn't reach a conclusion based on what I read, so I decided to compare the two means of transporting fluids by trains myself.

Here are some base facts:
Fluid wagon:

• can hold 75k units of a liquid.
• is heavier than cargo wagon. Train doesn't accelerate as fast as with cargo wagons.
• can be loaded/unloaded extremely fast. It can be filled in just 4 seconds. I wasn't able to measure exact unloading speed, but I assume it is same as the loading speed.

Cargo wagon:

• can hold 100k units of a liquid.
• swapping full barrels for empty ones is also pretty quick, thanks to barrels' small stack size.

So, cargo wagon is lighter, can hold more liquid and is comparatively fast to load (if not faster). It seems that it is superior to fluid wagon, doesn't it?

I made a test to see how fast a train with cargo wagons and a train with fluid wagons brings 900k water from a pumping station. I used trains with 3 wagons. I actually made two tests, one with the pumping station 100 rail pieces away and the other one with a distance of 500 rail pieces. I used 6 assembly machines 3 filled with Speed modules 3 to do the barreling job.

Here are the results:

• Long distance test: Fluid wagon train: 4 minutes, 26 seconds; Cargo wagon train: 3 minutes, 38 seconds
• Short distance test: Fluid wagon train: 2 minutes, 26 seconds; Cargo wagon train: 3 minutes, 15 seconds

Notes:

• The actual target amount of water was 898k, because residue water in pumps cannot be read by circuit network. The idea was to have cargo wagon train make 3 trips and fluid wagon one 4 trips to account for the difference in capacity.
• Cargo wagon train didn't perform much better in short distance test, because it was waiting for previous batch of barrels to be filled. I used 3 sets of barrels. One waiting in each station and one being carried by the train.

Conclusion:
The test made me aware that carrying capacity of a wagon is not the only comparing criterion. Another one is to compare how fast the wagons can feed their contents to the piping system. And while the cargo wagon carries more water faster, the fluid wagon unloads faster. 75k liquid in 4 seconds is 18750 liquid per second per wagon. 1 Assembly machine 3 with Speed modules 3 gives 937,5 liquid per second (Base recipe: 250 liquid per second and 3,75 crafting speed). To match the fluid wagon number, you'd need 20 moduled Assembly machines. And that doesn't count for moving the barrels. 40 assemblies would double the barreling speed, leaving you with 2 seconds to unload the barrels, split them and feed them to the assemblies. I don't think that is possible. Also, that amount is per wagon. With 3 wagons, you'd get gigantic unloading station.

That speed is not really needed, however. If the trip is long enough, the barreling process finishes while the train is going. Therefore I recommed fluid wagons for shorter trips and cargo wagons for longer ones.

I'm also uploading saves I used for testing. Just turn on the power switch in the middle (on screen when you load) and watch the trains go at it. The numbers there show how much water (in k) is already transported. There are also timers near destination stations, which stop when target amount of water is reached.

Notes:

• Cargo wagon train seems to always sneak one more load of barrels before it is stopped, causing the 3 digit display to overflow.
• Factorio ticks 60 times per second. But when I had the timer show 60 ticks as a second I ended up with a really slow clock. When I tweaked the timer to treat 30 ticks as a second, I finally got it to show proper time. I am not sure why.

[grimdanfango]

The key personal-preference factors for me would be:

• On the one hand, fluid wagons are just a whole lot less faff to set up, and don't require you to maintain and monitor a stock of barrels

• On the other hand, barrels are presumably a far more space-efficient method to store up fluid. By my reckoning, you'd fit 4.8 fluid-storage-tanks-worth into a single steel chest, so given tanks' 3x3 dimensions, that's 43.2x better space efficiency

[Aeternus]

Stock wagon:
- 100k fluid in barrels
- Has 400 units while fully loaded
- Max unload/load speed (assuming emty barrels loaded on one side, full barrels unloaded on the other using filter stack inserters) = 6x 12 items per second = ~5.6 seconds to fully exchange the wagon's cargo.
- Requires at least 2 tiles room at both sides of the station for the above configuration
- Fluid has to be loaded/unloaded in assemblers, which requires some space and extra power, doesn't need to be at the rail station. However, moving barrels with belts or logistics means no problems with fluid flow rates.

Fluid wagon:
- 75K fluid straight pumpable.
- Heavier then a stock wagon, affects train accelleration badly.
- Max unload/load speed (assuming 3 pumps hooked up straight to storage tanks for maximum performance), ~3.5 seconds to fully load/unload.
- Requires at least 5 tiles room (pump+tank) in above configuration. Smaller configurations are possible but increase load/unload time.
- Fluid directly usable, but getting it to where it needs to be can run you into flow rate problems.

Both have their merits. Fluid wagons are much simpler to use, but their weight limits the amount of wagons you should use (unless you use more locomotives). I prefer them for oil from wells to refineries (in 1 loc/2 tankwagons configurations) and acid to uranium mines (1 loc 1 tankwagon more then suffices). Massive bulk transports of fluids however would benefit from barrelling, both because of the 33% capacity bonus over fluid wagons, and the reduced weight of stock wagons.

[Steambirds]

How do I speedily load/unload a fluid wagon? It always takes like a minute for me.

[againey]

How do I speedily load/unload a fluid wagon? It always takes like a minute for me.

How many pumps are you using per wagon? You can use up to three: one within the first two tiles of the wagon, one along the middle two tiles, and one along the back two tiles.

[Aeternus]

How do I speedily load/unload a fluid wagon? It always takes like a minute for me.

Orzelek came up with this:

Important: Pumps should connect directly to the storage tanks. Storage tanks should be full for a train loading, or empty for a train unloading. With 3 pumps in this configuration (1 pump per train tank will connect) it will load/unload a wagon in under 4 seconds.

[Shokubai]

For me it's simplest to always do liquid rail and Local canning. If my delivery location for a liquid is not adjacent to where the liquid is needed I can it and let the bots deliver it. Dealing with full/empty cans at remote bases (uranium mining) was simply not fun when i could simply plop one tank a pump and some pipe. If a mine emptied of ore i can reverse the pump and haul it elsewhere.

[Kametec]

- Max unload/load speed (assuming emty barrels loaded on one side, full barrels unloaded on the other using filter stack inserters) = 6x 12 items per second = ~5.6 seconds to fully exchange the wagon's cargo.

I've noticed that inserters' stack size over 10 is lost on barrels. If you put 12 barrels in a chest and connect it by stack inserter to another chest, it will cycle 2 times. I'm not sure if that is a feature or bug.

[Shokubai]

- Max unload/load speed (assuming emty barrels loaded on one side, full barrels unloaded on the other using filter stack inserters) = 6x 12 items per second = ~5.6 seconds to fully exchange the wagon's cargo.

I've noticed that inserters' stack size over 10 is lost on barrels. If you put 12 barrels in a chest and connect it by stack inserter to another chest, it will cycle 2 times. I'm not sure if that is a feature or bug.

would report as bug

[Terukio]

Before bots, I believe rail tankers are an easier method of transferring liquids via trains. However, later game bots can give you more throughput by barreling it, which I believe requires more infrastructure and logistics to do efficiently, which should be rewarded with more throughput. With this in mind, the more capacity and quicker train speed comes as a nice improvement when you made it to bot logistics, until then rail tankers and slower trains should suffice. This gives a player the incentive to move forward.

If anything, make the rail tanker the same weight and hold the same capacity as a cargo wagon with barrels. This would give the end game player more options to how they want their base to be.

Personally, I like the sense of progression, intended or not, that is part of moving from rail tankers to cargo wagons.

[torne]

- Max unload/load speed (assuming emty barrels loaded on one side, full barrels unloaded on the other using filter stack inserters) = 6x 12 items per second = ~5.6 seconds to fully exchange the wagon's cargo.

I've noticed that inserters' stack size over 10 is lost on barrels. If you put 12 barrels in a chest and connect it by stack inserter to another chest, it will cycle 2 times. I'm not sure if that is a feature or bug.

Stack inserters never move more than one stack of that item, no matter how high the bonus. Barrels only stack to 10, therefore they can only move 10 at a time.

[NightCabbage]

Important: Pumps should connect directly to the storage tanks.

Why can you not have Pump -> Pipes -> Tank ? Does that make it slower?

Also, can you have the 3 pumps on the same side?

And what's stopping you from having 6 pumps (3 on either side)?

Thanks!

[terror_gnom]

1) Yeah, Pipes do heavily decrease throughput
2) You can´t place the 3 required tanks on one side
3) only 1 Pump can connect per "third of a fluid tanker"

[Aeternus]

- Max unload/load speed (assuming emty barrels loaded on one side, full barrels unloaded on the other using filter stack inserters) = 6x 12 items per second = ~5.6 seconds to fully exchange the wagon's cargo.

I've noticed that inserters' stack size over 10 is lost on barrels. If you put 12 barrels in a chest and connect it by stack inserter to another chest, it will cycle 2 times. I'm not sure if that is a feature or bug.

would report as bug

Probably has to do with stack inserters not being able to pick up more then a single stack. If max stack < inserter capacity, max stack is used. Doubt that is a bug, and I was unaware of this. It raises unload time to 6.7 seconds for barrels, which is roughly on-par with unload speed for fluid stations (taking into account the 25% extra volume unloaded).
There's an additional bonus to barrel loading stations. 6 wagonloads of buffer can be put at each side, both for empty and loaded barrels. When loading multiple trains in rapid succession, barrels definately have an advantage. Fluid stations will need a little longer to get their storage tanks back up to full capacity, or emptied.

Pump-Pipe-Tank slows down the max flow rate by a significant amount. If you need maximum performance out of your station, no pipe should be between the tank and the pump loading the train.
Only one pump will connect to each of the 3 tanks on the train, so you can use at maximum 3 pumps. You can put the 3 pumps on the same side, but then you can't hook all 3 up directly to the storage tanks, which causes a slowdown in the loading speed. If you don't care that loading the wagon takes a few seconds longer, then you can simply omit the middle pump in the station I screenied entirely.

[NightCabbage]

1) Yeah, Pipes do heavily decrease throughput

Oh damn, any reason for this?

ie. aren't the holes in the pump, tank and pipe all the same size?

Pipes just have a lower throughput?

[terror_gnom]

For more Detail, I suggest reading this post:
viewtopic.php?f=18&t=19851

[mrvn]

1) Yeah, Pipes do heavily decrease throughput
2) You can´t place the 3 required tanks on one side
3) only 1 Pump can connect per "third of a fluid tanker"

Sure you can place 3 tanks on one side. Just rotate them to fit. The top tank should have the pump at the bottom and the bottom tank have the pump at the top. The middle can go either way.

I always put 3 tanks directly to the pumps. Then a line of pipe on the other side of the tank. Connect a pump to that line of pipe and a tank to that pump.
So 4 tanks and 4 pumps in total.

The idea is that the 3 first tanks are purely for loading and unloading. For loading they need to be full, for unloading they need to be empty. This allows me to signal for a train (enable the station now, using signals earlier) when the 3 tanks are full/empty. The 4th tank is a buffer to bridge the gap between the 3 tanks being full/empty and the train arriving.

[terror_gnom]

Yeah, right. I meant that its not possible for 2 or more fluid tankers... I somehow cant think in low quantities anymore

[mrvn]

I guess for multiple tanks just place the tanks for each wagon on alternate sides. Somehow I never had the need for more then 75k fluid per 20s or however long it takes for a train from the waiting bay to arrive and unload.

I haven't even used waiting bays for fluid wagons yet.

[Kametec]

I like busy railroads, so I made a really big power plant and dumped water pumps in favour of a rail station to bring water. It needs crazy amounts of water and I couldn't get it running on full load reliably until I learned how to make quick unloading station, like the one shown few posts above. It is quite simple to get a situation where you need as much fluid per second as you fancy.