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Who needs a vaporiser? And why is it important?

"Vaporisers are only for cold climates" An often-heard statement and common knowledge since, well, forever. But what if we told you that is a common misconception?

According to popular belief, a mild climate with relatively stable temperatures makes vaporisers unnecessary as it provides enough energy to keep the natural vaporisation going inside an LPG tank. And yes, you can get by without a vaporiser. So why do we still claim the myth to be false? Simply because a vaporiser is the ultimate cost-saving device. Read on, and we will show you why.

What is a vaporiser?

A vaporiser is a device that turns a substance, in this case LPG, into vapour. Simply, LPG enters the vaporiser as a liquid end exits as a gas.

One major benefit is that a vaporiser allows you to draw as much LPG as you need from the tank – even the 30% which are usually left at the bottom. Further down on this page you will find the 8 most compelling reasons for installing a vaporiser.

Welcome to chemistry class

In order to fully understand the benefits of a vaporiser, we need to start by looking at how vaporisation actually works and why it is necessary.

Essentially, vaporisation is a phase change from liquid to vapour. Since it is transported and stored as a liquid under pressure, LPG must be converted to vapour before being combusted by LPG-consuming equipment. Insufficient vapour pressure will cause the equipment to shut down or produce less energy than required.

Vaporisation requires energy

With natural vaporisation, the phase change occurs within the tank and the gas leaves the tank as a vapour. When you draw gas from the tank, the pressure inside it drops and the liquid starts boiling. Part of the liquid then vaporises, pressure is restored and the liquid stops boiling. High ambient temperature increases the rate of vaporisation and thereby the outlet pressure. The higher the pressure, the more LPG you can draw from the tank.

If, on the other hand, the ambient temperature is too low, the system pressure drops because of a lack of natural vaporisation, in which case you may not be able to draw as much LPG as you need to run your equipment.

Tank size and liquid level are crucial

The energy (i.e. heat) needed for natural vaporisation is transferred from the surroundings through the tank walls to the liquid inside. The surface where the liquid LPG is in contact with the tank walls is also known as the heat transfer area. This area becomes smaller the less LPG is in the tank.

As the liquid level decreases, the tank temperature – and with it the outlet pressure – drops until reaching a point where the tank is too cold for any natural vaporisation to take place. The lower limit can be up to 30 percent, which means that about one third of an LPG tank's capacity is actually useless – but you still pay for it.

Vaporisation by means of a vaporiser

Whereas natural vaporisation occurs within the tank, a vaporiser moves that process outside the tank. That means that instead of extracting vapour, you extract liquid LPG.

As explained above, vaporisation is necessary in order for you to draw LPG from your tank. The question now is whether you can rely on natural vaporisation or you need a vaporiser.

Tank and Vaporiser
8 Reasons to choose a vaporiser

Here are the 8 most compelling reasons for installing a vaporiser:

1. Higher capacity (kg LPG/h) without investing in new tanks.

If you rely on natural vaporisation, there are only two ways to increase capacity: To install a bigger tank or add more tanks. A vaporiser lets you draw as much LPG as you need from the tank – even the 30% which would be left unused when using natural vaporisation only.

2. Stable production all the time

As mentioned before, natural vaporisation causes pressure drop and reduced capacity. The stable pressure provided by a vaporiser allows you to adjust your burners more accurately while avoiding the risk of your equipment unexpectedly shutting down or producing less energy than required.

3. Less tank filling operations

No "useless" tank capacity means fewer deliveries and larger volume per delivery to the benefit of both gas re­tailers and consumers. As any transfer of gas from one vessel to another constitutes a potential risk, it is good for safety too. Add to that the environmental bonus of fewer emissions during transfer, and we certainly have a winner.

4. Makes it easier to use low-price butane

Ok, back to chemistry class for a second. When mixed with propane, butane reduces the natural vaporisation rate and the tank outlet pressure. That is because ­butane is less volatile than propane and boils at -0.5°C whereas propane boils at -42°C. A vaporiser makes it easier to use a mixture of butane/propane or pure ­butane – and both are cheaper than pure propane. The vaporiser also prevents accumulation of butane, caused by its higher boiling point, so you can maintain a homogenous mixture.

5. No accumulation of oil and heavy ends in the tank.

When drawing liquid LPG from the tank into the vaporiser, any impurities in the gas are caught by a filter in the pipeline instead of accumulating as residue and reducing vaporising capacity. This makes potentially dangerous tank draining procedures unnecessary.

6. Higher capacity (kg LPG/h) when using underground tanks

Safety concerns and local regulations make the use of underground tanks widespread in certain areas, and from a safety perspective they are a very good choice. But since an underground tank cannot absorb as much heat from its surroundings as its above-ground counterparts, its capacity is much lower when relying on natural vaporisation.

7. Increased tank lifetime

Natural vaporisation makes the tank surface cold and covered in dew; the perfect conditions for algae and rust. A vaporiser can help reduce maintenance costs and extend the lifetime of the tank.

8. Savings on pipe installations

Placing the vaporiser close to the consuming equipment lets you have liquid pipelines almost all the way. And as they can be designed with a smaller diameter, they cost less. Even vapour pipelines can be downsized due to more stable pressure.

Underground tank

How to know if your tank needs a vaporiser?

When estimating whether your business would in fact benefit from having a vaporiser installed, the decision is based on a worst case scenario estimate. In other words, we estimate the natural vapour ability of your equipment at the least favourable conditions to ensure that your production will be running no matter what happens, i.e. the lowest temperature your tank will reach and the maximum capacity you will need to draw from your tank and therefore the minimum level of LPG in the tank.

Download: Vaporiser - an investment that will secure your profit

A vaporiser ensures that you can enjoy the full volume of your gas tank without pressure loss. This e-book presents the importance and benefits of a vaporiser - as you just read about above.

Download the vaporiser e-book