What withdrawal volume do I get out of one gas cylinder?
How much gas do I actually get from my cylinder—and how long will it last under continuous operation? Many users—whether campers, grillers or technicians—underestimate how strongly the withdrawal rate of liquefied gas depends on external factors. Although every gas cylinder states a filling mass, that does not tell us how much energy per hour is actually available. What matters is not only the cylinder size, but also the withdrawal duration, the ambient temperature and, to a lesser extent, the cylinder’s design or material.
In this article we show, using practical values, what withdrawal masses are realistic for 5 kg, 11 kg and 33 kg cylinders, how the output changes during continuous operation, and why cylinders may ice up under high demand. It is ideal for anyone who wants to reliably plan for grilling, heating, cooling or commercial use.
Why is the withdrawal rate from gas cylinders limited?
Whether for grilling, heating or cooling—many users are occasionally surprised that the gas appliance “weakens” even though the cylinder is not empty. The reason lies not in the content, but in the physical processes when transitioning from liquid to gas.
Liquefied gas, a mixture of propane and butane (or in cylinders and cartridges often in nearly pure form), is under pressure in liquid form in the cylinder. When the valve is opened, a portion of the gas evaporates—this process absorbs heat from the surroundings. The higher the withdrawal rate, the faster the cylinder cools. That can lead to the evaporation slowing—and the usable gas per hour dropping significantly.
The gas type also plays a role: butane has a significantly higher boiling point than propane. While propane still evaporates even at –40 °C, the limit for butane is already around 0 °C. If the mixture is rich in butane, the withdrawal performance drops noticeably at low temperatures.
A typical warning signal: icing of gas cylinders. This shows that the demand exceeds the evaporation capacity—especially with smaller cylinders, undersized cylinder installations or a cold environment.
If too much gas is withdrawn at once, vaporisation is often insufficient – this can cause the flame to become smaller or irregular.
What influences the withdrawal rate?
The actual withdrawal rate from a gas cylinder depends on several factors. Even with identical filling mass, the usable performance may differ significantly depending on the circumstances. For reliable planning—whether for heating, grilling or workshop use—it is worthwhile knowing these influencing factors:
- Cylinder size and design
The larger the volume of liquefied gas in the cylinder, the higher the evaporation capacity. A 33 kg gas cylinder, for example, can deliver significantly more gas than a 5 kg cylinder because it has a greater surface area for evaporation. The cylinder material and wall thickness also affect heat uptake from the surroundings. Differences exist between the evaporation performance of steel, aluminium and composite cylinders. Material properties and wall thickness have the greatest influence here. Steel has a higher thermal conductivity than aluminium or composite, which may lead to faster evaporation in steel cylinders—though certain constructions of composite cylinders can also promote evaporation. - Ambient temperature
Liquefied gas needs heat to evaporate. At low temperatures—especially below 0 °C—the vapour pressure drops strongly. The gas evaporates more slowly, and the cylinder delivers lower output. Butane content in the mixture may further aggravate the problem, since butane no longer evaporates around 0 °C. - Duration and mode of withdrawal
While for short withdrawal—e.g. grilling for a few minutes—a high performance is often still available, the withdrawal rate drops significantly during extended use. The cylinder cools, and the evaporation process slows. The result: much lower usable energy per hour. - Consumer appliances
The connected appliance also influences the withdrawal performance. A heater rated at 12 kW consumes much more gas than a small catalytic heater rated at 2.5 kW. The higher the demand, the sooner the cylinder may reach its physical limits. Therefore, it is important to dimension the liquefied gas installation accordingly, so that icing and failure of the gas appliance can be avoided.
The higher the appliance rating, the more gas is required – if the system is undersized, the gas cylinder may freeze. A patio heater with 12 kW consumes significantly more gas than a small catalytic heater with 2.5 kW.
Withdrawal amounts at a glance: 5 kg, 11 kg and 33 kg cylinders
How much liquefied gas can actually be withdrawn depends—as described—strongly on external factors. Nevertheless, typical practical values can be given as orientation for various use cases.
Withdrawal volume from a 5 kg gas cylinder
From the smallest propane‑butane cylinder, surprisingly much energy can initially be withdrawn: in the short term it can deliver about 1.5 kg of liquefied gas per hour, corresponding to a power of about 19 kW. With increasing withdrawal duration, however, the performance drops significantly. During extended use, only about 0.2 kg per hour is available—this corresponds to about 2.6 kW.
Withdrawal volume from a 11 kg gas cylinder
From the 11 kg cylinder—which is more than twice as large—one can withdraw a striking amount of energy in the short term: up to 2 kg of liquefied gas per hour, corresponding to about 25 kW. During longer or continuous withdrawal, however, this output declines continuously. For long-term use, one should expect a continuous output of about 4 kW.
Withdrawal volume from a 33 kg gas cylinder
With its nearly three to six times filling mass, the 33 kg cylinder is the largest commonly available variant in Germany. For short withdrawal, one can expect up to 3 kg per hour—this corresponds to about 40 kW. During extended, steady use, however, the cylinder still delivers a respectable continuous output of nearly 8 kW.
Calculation example: how long does a cylinder last?
A heater of 5 kW consumes about 0.39 kg of liquefied gas per hour. From this it follows:
- 5 kg cylinder: approx. 12 to 13 hours
- 11 kg cylinder: approx. 28 hours
- 33 kg cylinder: approx. 84 hours
These values apply under ideal conditions (e.g. ambient temperature above 15 °C). If the temperature drops or the device is used continuously, the withdrawal mass may fall significantly—especially for small cylinders.
Practical tips: avoiding icing and optimally using the cylinder
In some applications one may reach the physical limits of a cylinder—especially under long or intense withdrawal. The most frequent consequence: the cylinder ices up externally, performance drops and the connected appliance operates unreliably or shuts off. With a few simple measures one can counteract or prevent this:
- Check dimensioning – the cylinder should match the rating of the gas appliance(s).
- Use larger cylinders – e.g. 8 kg or 11 kg instead of 5 kg.
- Switch multiple cylinders in parallel if a single one cannot cover the gas demand.
🚫 What you should never do:
- Do not knock off ice from the cylinder – risk of damage or leaks.
- Do not strongly heat the cylinder – overpressure and gas release may result.
- Do not lay the cylinder down to “draw out” residues – it must stand upright so that liquid phase is not drawn into the system.
- Do not operate a gas grill with cylinder indoors.
Frozen gas cylinders are always a warning signal: the withdrawal rate exceeds the vaporisation capacity.
Conclusion: planning is decisive—not only filling mass counts
Many users choose a gas cylinder based only on the filling mass or size. But for the actual use of a gas appliance—grill, heater or commercial consumer—the short‑term and continuous withdrawal rates can be decisive. They determine how much power per hour is available, and depend heavily on cylinder size, ambient temperature, withdrawal duration and appliance load.
Anyone who wants to plan reliably should not rely on theoretical values alone, but understand the physical limits of the cylinder—especially in continuous operation or at low temperatures.
FAQ: common questions on withdrawal from gas cylinders
- How many kilowatts does a cylinder deliver?
Depending on cylinder size and temperature: short‑term up to 40 kW (for 33 kg cylinder), but the power drops during continuous withdrawal. - Why does my gas cylinder ice up when grilling or heating?
Because evaporation cools the cylinder. If withdrawal demand is too high, moisture freezes to the cylinder surface. - How long does an 11 kg gas cylinder last?
With a 5 kW device approximately 28 hours—dependent on device consumption and ambient temperature. - What role does ambient temperature play?
The colder it is, the lower the evaporation and thus the withdrawal rate. In cold conditions pure propane has clear advantages over butane. - How can I increase the withdrawal rate?
Use larger cylinders, connect multiple cylinders in parallel, or increase ambient temperature (though outdoors that is generally not feasible). - Which is better: propane or butane?
Propane is winter‑capable (evaporates down to –40 °C), butane only conditionally. In winter pure propane is preferable.
