Why Does Freezing of LPG Cylinders Occur and How Do We Eliminate the same?

As LPG is the mixture of mainly two types of Gases Propane & Butane with some heavy Carbone as per IS   the liquefied gas in the Cylinder is in liquid form under high pressure. As the pressure drops at the time of Use of LPG in the Burners/ Heating System, more LPG will evaporate to replace what was consumed in the system. When a liquid becomes a gas, it absorbs energy equivalent to heat of vaporization of LPG (Latent Heat Required for Vaporization) to destroy the intermolecular forces that hold it in the liquid phase. If the liquid evaporates slowly enough, the surrounding heat of the cylinder will transfer to liquid in LPG and smooth vaporization takes place in the cylinders/tanks. If the phase change occurs rapidly, for example when the we require more LPG from cylinders more heat is required for vaporization of liquid to Gas, as faster evaporation is required faster heat transfer than the surroundings can transmit, so the system temperature drops. When it’s humid outside, we’ll notice condensation and even freezing of water molecules on the outside of the Cylinder. This is also called sweating of Cylinders.

Why Did that Happen?

Once we understand what a sweat cylinder is, we need to understand why it is happening in our LPG System/ Manifold/ Tank. The reason is simple. This is due to the incorrect design of the Manifold System/ Piping in the Process. If the system is Designed without consideration of Peak Load / average load & behavior of Gas Equipment as well as Working Pressure of Equipment, this problem arises.

Read on for some useful tips on how to protect and eliminate your LPG cylinder from freezing/sweating.

Proper Design of LPG Manifold System:

What’s one of the best ways to prevent an LPG cylinder from freezing? The answer is simple. Calculate the peak, average & study the behavior of Kitchen/Heating system uses as well as atmospheric conditions of the geographical area. The vaporization rate of LPG in Cylinders depends on atmospheric conditions. Proper Designing is the only solution to eliminate the freezing & residual LPG. 

Line Pressure

Propane & Butane shrinks with decreasing temperature. In cold weather, the vaporization rate of the cylinder will decrease accordingly and the pressure of the cylinder also decreases. If we keep higher line pressure the evaporation in the cylinder will go slow. To eliminate this situation, we design our line size as minimum pressure drop occurs in line i.e. we use line pressure just above the working pressure of equipment. by this we also reduce residual LPG in cylinders at the time of exhaust of LPG.   

Cylinder / Manifolding area

Depending on where you work or live, storing a cylinder outdoors means keeping it frozen. We understand that this is not an ideal situation and is likely a recipe for low cylinder pressure and severe headaches. Keep the cylinder manifold in a well ventilated area below the shed where direct dew does not contact the cylinder & manifold.

The ideal place to store is outdoors in a shady, dry place. Rain, snow, and moisture cause rust, which damages the tank and shortens its life.

Maximum & Minimum Working Temperature

Maximum working temperature of LPG system/ Cylinder is 55 C & minimum working temperature is -20 C. While both are temperature extremes at both ends of the spectrum, it is advisable to be extra careful by never exposing yourself to direct sunlight and always protecting it from ice and snow. To keep working properly.

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