Complete Gas Supplies

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Complete Gas Supplies - The Bulk Gas Specialist
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Complete Gas Supplies - Your One Stop Gas Supplier and Installer

Questions and Answers on Gas Supply

QUESTION 1   What is the short name for Liquefied Petroleum Gas?


QUESTION  2   Where does Liquefied Petroleum Gas come from?

ANSWER  In the process of making petrol from crude oil, one of the by-products is a mixture of petroleum gases. The mixture is made-up mainly of two gasses called Propane and Butane.

LP Gas contains around 50% Propane and 50% Butane

What is meant by the word “liquefied”?

ANSWER When the Petroleum Gas comes from the refinery it is put under pressure which causes it to turn into a liquid.  It is “liquefied”. The pressure used is about 700 kPa.

QUESTION 4  Why the Petroleum Gas should be liquefied?

ANSWER  By the liquefying action about 270 volumes of LP Gas are reduced to ONE volume of liquid – this makes storage and transportation much easier .

It stays under pressure in the container while in liquid form (600-700kPa).

QUESTION 5  How is LPG stored and transported?

ANSWER  In order for the LPG to remain a liquid it must remain under pressure. Therefore it must be pumped into a specially designed container, or vessel which can hold the pressure of about 700kPa.  Those that are portable are commonly called cylinders .

QUESTION 6  Are there various sizes of cylinders?

ANSWER   The cylinders vary in size from one which holds 1,4 kg of LPG to one which holds 48 kg of LPG.  The various makes of cylinders look slightly   different from each other and each supplier paints his cylinder his own  colour.  But all cylinders are made according to very strict safety standards such as SANS Code No 219 .

The most common sizes are 4,5 kg, 6, 9, 14, 19 and 48 kg cylinders.

QUESTION 7  Does LPG burn?

ANSWER  Like the other fuels – diesel, paraffin and coal – LP Gas also burns when it is lit by a source of ignition such as – open flame, spark or a red hot surface.

QUESTION 8  Does LPG burn easier than the other fuels?

ANSWER  LPG burns much easier than other fuels mainly because, even at room temperature when the pressure is released by opening the cylinder valve the liquid LPG immediately changes into a gas.  This is the reverse process to liquefying, as one volume of liquid forming about 270 volumes of gas.

QUESTION 9  Does the LP Gas need air to burn?

ANSWER  Like all open fires air must be present for the flame to burn.  So the LPG then mixes with air to form the big volume of flammable mixture.  In fact the LPG liquid is so economical that one

QUESTION 10  What happens to LPG in the cylinder – when it gets hot?

ANSWER   It will expand. Because LPG liquid can expand (get bigger) greatly when the temperature rises, it is important to have space in the cylinder for the LPG to expand into.

QUESTION 11  Can a cylinder be overfilled?

ANSWER  Yes. Cylinders should only be filled to 80% of the cylinder capacity. This allows for expansion into the remaining 20% space

If the cylinder is filled to the top (over filled), and then warmed the liquid expands and the cylinder can burst open. This is very dangerous and could cause a serious fire and possible injury. It should therefore be kept away from extreme heat.

QUESTION 12  When can the cylinder burst?

ANSWER  Cylinders are made to such high safety standards that with normal use they will not, just burst.

If however, the cylinder is heated in an open flame or left on an electric stove plate that is switched ON the cylinder will get red hot and burst open.

It will cause a very serious fire and damage to property.  Never put a cylinder on a stove.

All users of cylinders must be informed of this danger.

QUESTION 13  Why are there two arrows on the LPG cylinders?

ANSWER   The two arrows on each cylinder tell you that the cylinder must be transported and used in an upright position.

The reason being that if the cylinder is lying on its side and there is a leak, liquid LPG will come out.  Remember from  – one volume of liquid will mix with air to make 10 000 volumes of flammable mixture which can explode if there is an open flame or spark nearby.

In the upright position only gas will escape when a valve leak occurs.

QUESTION 14   Can you see LP Gas?

ANSWER  No. LPG is like clear water – it is colourless and it also flows like water.  Like water, LP Gas will flow to the lowest point, as it is much heavier than air.

QUESTION 15  Is it dangerous for LP Gas leaking from a cylinder to flow down into drains?

ANSWER  Just like water, the leaking LP Gas will look for the lowest point and will for instance, flow down a drain, or collect in a hollow in the ground, or in the basement of a building.

Any source of ignition, such as an open flame, burning match, burning cigarette, light switch spark, lighter, motor car alternator or dynamo or red-hot surface near the leak or even, in the case of the drain, some distance away, can cause the leaking gas and air mixture to ignite and even explode.

  Why does LP Gas stink?

ANSWER   In order to assist in detecting LPG leaks a smelly chemical has been added to the LP Gas called ETHYL MERCAPTAN.  The odorant stinks like rotten eggs.  Those working with LP Gas should get to know and recognise the smell so that they can quickly detect if LPG is leaking.

QUESTION 17  How do I find the place where LPG is actually leaking?

ANSWER  The method used to find the leaking joint, valve, hose connection or hole in a cylinder, is to use soapy water which is brushed, sponged or squirted on the place where the leak seems to be coming from – bubbles will form at the leak.

The operation (e.g. filling/ storage /transportation) should be stopped until the leak is repaired either by yourself (if trained to do so) or by your supervisor.

Remember NEVER use a match or open flame to find a leak. The leaking gas could explode and cause injury.

QUESTION 18  Is LP Gas toxic – poisonous?

ANSWER  LP GAS IS NOT TOXIC – NOT POISONOUS but if you breathe sufficient volumes in a confined space (small room) you will get sick and it could even cause suffocation.  That is why it is important to ventilate (open doors and windows) after any leakage or spills of LP Gas.

QUESTION 19  Will it harm me to get LP Gas on my skin?

ANSWER  LP Gas in the liquid form boils and forms a gas at -22°C – which is very cold indeed – water freezes at 0°C.  Therefore if LP Gas liquid spills onto your skin you will suffer a skin burn called frostbite – a drop in your eye could blind you.

By sensible handling of the product such burns will be eliminated

Protective clothing such as gloves and eye protection should be worn if exposure to this hazard is likely to occur.

QUESTION 20  Is it safe to fill a cylinder which is rusted?

ANSWER  Rust and caked paint should be removed from the surface when you see corrosion so that the surface can be properly inspected. Bad corrosion can cause a weakening of the cylinder shell and it may not be able to with stand the pressure of LP Gas.

Be careful to inspect the place where the foot ring is welded to the cylinder shell, especially underneath.

If you have any doubt whether the rust is so deep that it will affect the safety of the cylinder, ask your supervisor for guidance.

If the foot ring is so damaged that the cylinder is unstable when left standing, it should not be filled and sent away for maintenance

QUESTION 21  Why is it dangerous to fill a bulged cylinder?

ANSWER   Cylinders, when made, have a reasonably uniform shape.  If the cylinder has been overfilled or overheated it is possible for the cylinder shell to change shape – its uniform shape bulges or changes – this means that the walls of the cylinder shell have been stretched and damaged.

Such cylinders should not be refilled.

If in doubt ask us!

For more Contact Us:

David Parker
Mobile: +27 (0) 82 859 9679
Port Elizabeth, Eastern Cape, South Africa