Pumped Liquid Engine

Kit (Pumped Liquid Engine)

Fabrication
Created with	Rocket Manufactory (Tier One)
Cost	60000 Energy, 15g Steel, 5g Electrum, 10g Constantan
Temperature
Flashpoint	373K (100°C)
Autoignition	573K (300°C)
Other properties
Paintable	Yes
Stack Size	1
Prefabs
Prefab Hash	1921918951
Prefab Name	ItemKitPumpedLiquidEngine

Pumped Liquid Engine

Operation
Base Power Usage	200W
Rocket Mass Contribution	500kg
Max Thrust	17,6kN
Efficiency	140%
Exhaust Velocity	5,47km/s (Isp: 559s)
Contruction
Total cost	2,5g Iron, 17g Steel, 5g Electrum, 10g Constantan
Constructed from	Kit (Pumped Liquid Engine)
Other properties
Paintable	Yes
Prefabs
Prefab Hash	-23091440019
Prefab Name	StructurePumpedLiquidEngine

Description

"Liquid propellants bring greater efficiencies with Pumped Liquid Engine. Two inputs are provided so Stationeers can seperate their fuels, the Setting variable controls the mixing ratio of the inputs. The engine is designed to run on Liquid Volatiles and Liquid Oxygen, some Stationeers have reported excessive thrust values by switching to Liquid Nitrous Oxide."
- Stationpedia

Comparison

Rocket Engines give you their max output in kN with this you can calculate what they can reasonably carry into orbit depending on the planet or moon you are on. Force = Mass * Acceleration. Acceleration is equal to the planet's gravity, Mass is given in kg per part of the rocket, and Force is kN. If your thrust force listed below is less than the weight of the rocket in kN then you will not even take off. It is better to have a thrust much higher than the weight of the rocket or else you risk running out of fuel on launch and on landing.

Liquid propellants bring greater efficiencies. Using Nitrous Oxide as oxidizer provides excessive thrust values. Keep in mind that N2O fuel mix is 1.9375 times heavier at same moles, or 2.15 times heavier at same volume, while thrust boost is around 1.5-1.7. Engine efficiency determines "bonus" thrust multiplier, meaning engine with higher efficiency will give more thrust consuming same amount of fuel. Thus using liquid engines is more favorable if one can cool fuel down, moreover Pressure Fed Engines consume fuel inversely proportional to its temperature. On the other hand if Volatiles and Oxygen are in excess (e.g. farm on Vulcan) is may be much easier to opt for Pressure Fed Gas Engine. It will provide ~40kN at 20°C.

Name	Power Usage, W	Rocket Mass Contribution, kg	Formal Max Thrust, kN	Tested Max Thrust, kN				Propellant consumption, mol/tick			Efficiency, %	Exhaust Velocity, km/s	Specifc Index Isp, s
				Using O2	Using N2O	Using O3	Using N2H4	Using O2	Using N2O	Using N2H4
Pumped Gas Engine	200	500	16.20	16.54	24.47	19.40	18.10	18.00	18.00		100	4.02	411
Pumped Liquid Engine	200	500	17.90	18.74	31.25	5.52	25.00	15.00	16.66		140	5.56	568
Pressure Fed Gas Engine	10	500	40.30	60.32	41.57			69.77	31.68		96	3.86	394
Pressure Fed Liquid Engine	20	500	29.30	38.84	59.70			27.23	28.16		160	6.31	644
Heavy Pressure Fed Gas Engine	10	750	62.60	93.87	64.75			118.45	53.83		88	3.54	361
Heavy Pressure Fed Liquid Engine	20	750	44.30	60.39	95.52			47.03	49.86		144	5.68	579
Update 0.2.6136.26812 - 01/28/2026 Rocket_Engines

Note: Hydrazine (N₂H₄) testing was performed at 282K (9C) for Liquid Pumped, and 500K (227C) for Gas Pumped engines. Methane and Ozone (O₃) tests performed at 128K (-145C) for Liquid Pumped, and 273K (0C) for Gas Pumped engines. Methane and Ozone performed very poorly in a liquid configuration.

Fuel Comparison

These values are based on manual testing. In all scenarios, the liquid fuels and oxidizers were pressurized using Helium at the same temperature as the fuel/oxidizer and stored in insulated pipe networks. Thrust remained stable throughout the tests.

Thrust (kN)

	Alcohol (300K)	Methane (120K)	Hydrogen (40K)	Hydrazine (300K)
Nitrous Oxide (300K)	37.35	30.703	31.672	-
Oxygen (120K)	18.603	18.676	24.595	-
Ozone (120K)	27.957	23.731	38.372	-
None	-	-	-	24.999

Data Network Properties

Click here to see/hide all the data network properties

Input Data (Write)

Parameter Name	Data Type	Value	Description
On	Boolean	0	Turns the device off.
		1	Turns the device on.
Setting	???		A variable setting that can be read or written, depending on the device.
Throttle	???		Increases the rate at which the machine workes (range: 0-100)
Update 0.2.4726.21691 - 19/01/2024 /Data_Network

Output Data (Read)

Parameter Name	Data Type	Value	Description
Power	Boolean		Can be read to return if the device is correctly powered or not, set cia the power system, return 1 if powered and 0 if not.
Error	Boolean		1 if device is in error state, otherwise 0.
Pressure	???		The current pressure reading of the device.
Temperature	???		The current temperature reading of the device.
Setting	float	70	A writable value to control the mixing Ratio percentage.
RatioOxygen	???		The ratio of Oxygen in device atmosphere.
RatioCarbonDioxide	???		The ratio of Carbon Dioxide in device atmosphere.
RatioNitrogen	???		The ratio of Nitrogen in device atmosphere.
RatioPollutant	???		The ratio of Pollutant in device atmosphere.
RatioVolatiles	???		The ratio of Volatiles in device atmosphere.
RatioVolatiles	???		The ratio of water in device atmosphere.
Maximum	???		Maximum setting of the device.
Ratio	float	Setting/100.0	read-only version of the Setting that converts from the percentage to a 0-1 fraction.
Ratio	Boolean		The current state of the device, 0 for off, 1 for on.
RequiredPower	???		Idle operating power quantity, does not nevessarily include extra demand power.
TotalMoles	???		Returns the total moles of the device.
RatioNitrousOxide	???		The ratio of Nitrous Oxide in device atmosphere.
PrefabHash	???		The hash of the structure.
Combustion	Boolean		The assess atmosphere is on fire. Returns 1 if atmosphere is on fire, 0 if not.
Throttle	???		Increases the rate at which the machie works (range: 0-100)
ReferenceId	???		Unique Reference Identifier for this object.
PassedMoles	???		The number of moles that passed through this device on the previous simulation tick.
Update 0.2.4726.21691 - 19/01/2024 /Data_Network

Plumbing

The most straightforward way to store fuel is to fill one tank with fuel, and the other with oxidizer. In order to make the gasses match the display on the rocket control computer, the ingredients must be connected to the correct port on the rocket engine.

After this, the fuel:oxidizer ratio needs to be set appropriately for the type of mix being burned. Because different liquids have different molar densities, this results in the following ratios after liquid density correction is applied:

Fuel:Oxidizer stoichiometric ratio for each mixture

	Alcohol	Liquid Methane	Liquid Hydrogen
Liquid Nitrous Oxide	52.72727%	60.6060%	51.8518%
Liquid Oxygen	39.189189%*	72.7272%	65.1162%
Liquid Ozone	52.72727%	69.7674%	76.3636%

*As of The Sanitation Update(July 2026), the Fuel:Oxidizer ratio being used for in-game stationpedia thrust value calculations is currently set to 75% on an Alcohol:Liquid Oxygen mix instead of the stoichiometric ratio. This leads to incomplete fuel combustion and severely reduced thrust figures.

Advanced rocket building techniques may use a single fuel tank containing both fuel and oxidizer. In this case, only one input needs to be used, at either 100% or 0% ratio depending on which port is being used. This prevents the use of Alcohol without Liquid Nitrous Oxide (and vice versa) as other fuels/oxidizers would cause them to freeze inside pipes. They may also evaporate at different rates if the mixed tank is kept at an insufficient pressure, resulting in a changing combustion ratio, or potentially even catastrophic freezing, if the tank isn't pressurized to prevent this from happening. Recommended pressurant choices are Helium or Hydrogen for their lower molar mass and phase stability properties.

Note that unlike the Pressure Fed Liquid Engine, only liquids are removed from the inputs. As such, only the amount of pressurant required to prevent evaporation on an empty fuel tank is required. If evaporation pressure is low enough, this pressurant can be stored within ullage, up until propellant tank pressure limits.

Build States

Click here to see/hide all the build states

Stage	Image	Relevant item	Tool for construction	Tool for deconstruction
1		1x Kit (Pumped Liquid Engine)	none	Hand Drill
2		5x Kit (Liquid Pipe)	none	Wrench
3		4x Steel Sheets	Welding Torch	Angle Grinder
Update 0.2.4726.21691 - Fri 19/01/2024 /Build_States