Gas Safety

GAS SAFETY

LPG SAFETY

(Liquefied Petroleum Gas)

Each year several fires occur in Saudi Aramco communities and also in local towns that are as a result of the malfunction or misuse of LPG [gas] appliances. Everyone has the responsibility to ensure that LPG appliances are in good condition and used correctly. The misuse of LPG can very quickly cause a large outbreak of fire, serious injuries or worse and significant property damage to buildings, housing and the destruction of your own possessions. Moreover, if a LPG storage cylinder is exposed to intense heat from a fire, under certain circumstances it can explosively rupture and a large volume of burning gas will be emitted. Always keep children and pets away from LPG appliances.

1. What is LPG?

LPG (liquefied petroleum gas) generally comes in two commons forms.

· Butane

· Propane

Butane is predominantly used in portable heaters and leisure applications such as barbecues, while propane is predominantly used in domestic heating, commercial cooking, industrial applications, etc.

LPG is usually stored in portable pressurized cylinders, but can be stored in larger quantities using bulk storage tanks. Being pressurized means that any time there is a leak, large quantities of highly flammable gas can be released and is a significant fire hazard.

2. LPG – properties

LPG is a liquid when pressurized in a cylinder and only becomes a gas when it is released. LPG as a gas is heavier than air, almost two times heavier for butane, and one-and-a-half times for propane. This means that if there is a leak the gas will collect in low points such as in drains and sewers and remain a fire hazard for some time before dispersing.

LPG is non-toxic and generally there are no injurious effects to humans except in large quantities by inhalation. LPG in its natural state is colorless, odorless and tasteless, and so to warn us of a leak the manufacturers add an odorant, which is a harmless chemical and gives LPG its characteristic smell.

LPG is highly flammable and has a very low flash point, −60 °C for butane, and −104 °C for propane, so at normal temperature & air pressure LPG will ignite when exposed to an ignition source. LPG burns with a very high temperature flame, above 1,000 °C for a pre-mixed flame. Moreover, LPG only needs a small quantity of gas in air by volume for flammability to occur, 1.9% to 8.5% for butane, and 2% to 10.3% for propane in air. This means that LPG needs lots of air to support combustion, externally air is readily available, but inside building adequate ventilation must be provided when burning LPG. Without an adequate supply of fresh air incomplete combustion of the LPG will occur and deadly carbon monoxide gas is produced. Carbon monoxide [CO] is a deadly colorless, odorless and tasteless gas known as the ‘silent killer’. The symptoms carbon monoxide poisoning is as follows:

Minor concentrations and exposure…

· Shortness of breath

· Mild nausea

· Mild headaches

Moderate concentrations and exposure…

· Headaches

· Dizziness

· Nausea

· Light-headedness

Prolonged and high concentrations can result loss of consciousness and death!

Treatment options for persons suffering from carbon monoxide poisoning:

· Get the victims into fresh air immediately

· Evacuate all persons from the affected house or building

· Open all windows and doors

· Turn off the LPG using the valve on the cylinder

· Call for emergency assistance and get persons affected by carbon monoxide to a hospital as quickly as possible

3. LPG – avoiding leaks

Due to the high flammability of LPG, even a minor leak is a serious hazard. This is made worse because humans may not be able to detect the slight odor from a minor LPG leak, but it is vital that any potential leaks are identified and quickly eliminated. But if you smell a strong gas leak you must TURN OFF the supply at the cylinder valve and have it investigated by a qualified and experienced plumber. NEVER use matches, cigarette lighters or any other open flame to search for gas leaks.

But if you suspect you have a minor gas leak, a simple and quick LPG leak detector can be made by adding some soap or washing up liquid to water. Sprinkle the soapy water with a rag or a brush all over the LPG pipework and cylinder valve, and wherever there is a leak bubbles will form. If you detect a leak no matter how small, IMMEDIATELY TURN OFF the LPG using the valve on the cylinder. Have a qualified and experienced plumber correct the leak before attempting to reuse the LPG equipment. Prevention of leaks is always better than having to deal with a dangerous LPG fire or worse an explosion. Suitable leak prevention measures are as follows:

· Use only purpose made steel-braided synthetic-rubber LPG hoses with threaded couplings and they will last for many years without leaks. Copper pipes can be used but they can be quickly worn out after many repetitive connections and reconnections, and so they are not recommended.

· Natural rubber hoses [often pink or light brown color] with ‘jubilee clips’ (adjustable clamps) MUST NEVER BE USED. LPG dries out the natural rubber and eventually it will split or crack causing a leak; and ‘jubilee clips’ or twisted wire easily work loose or can bite into the rubber if they are too tight causing leaks.

· If the cylinder valve is broken or the coupling threads are damaged, DO NOT USE and replace with a new cylinder.

· LPG is under high pressure in the cylinder, and so the regulator safely reduces the gas pressure before it reaches your LPG appliance. Accordingly, if the regulator is damaged or malfunctioning, high pressure gas may reach your LPG appliance resulting in potential serious injury and fire. If you suspect the regulator is not functioning correctly DO NOT USE and contact your local LPG dealer/vendor to check the regulator and replace it if cannot be properly and safely repaired.

· LPG can be used for cooking and heating, and so to avoid leaks or accidents it is very important that your LPG appliance is working correctly with no damaged control valves, flame failure devices, burners, etc. Have LPG dealer/vendor or a qualified and experienced plumber check your LPG appliance at least ONCE A YEAR.

If you discover a LPG leak inside a building YOU MUST do the following:

· AVOID panicking

· TURN OFF all control valves on your LPG appliances (cooking stoves, space heaters, etc)

· DO NOT use matches, cigarette lighters or any other open flames to search for gas leaks

· DO NOT operate electrical switches

· TURN OFF the LPG cylinder valve

· EXTINGUISH all open flames in the house (candles, oil lamps, incense sticks, etc)

· OPEN all doors and windows

· Call 110 and report the emergency inside Saudi Aramco communities, or 998 for Civil Defense in outside communities. Calling from a mobile phone inside Saudi Aramco communities, Dhahran area: 03-872-0110; Abqaiq area: 03-572-0110; Ras Tanura area: 03-672-0110.

If you discover a LPG leak outside YOU MUST do the following:

· AVOID panicking

· TURN OFF all control valves on your LPG appliances (barbecue grills, space heaters, etc)

· DO NOT use matches, cigarette lighters or any other open flames to search for gas leaks

· TURN OFF the LPG cylinder valve

· EXTINGUISH all open flames (candles, oil lamps, incense sticks, etc) within 6-meters (20-ft) of any LPG appliance, pipework or the cylinder

4. LPG – cylinders

When full LPG cylinders are heavy, have sharp edges in places and contain liquefied gas under pressure. The main hazards are as follows:

· Blast impact from a gas cylinder explosion or rapid release of compressed gas, following a mechanical impact or fire

· Impact from parts of LPG cylinders or valves that fail

· Fire resulting from the escape of LPG

· Impact from falling cylinders, or manual handling injuries

LPG cylinders have a robust steel construction, and the valve has a steel protector, and so in most cases will resist mild mechanical damage. But there are limits to this protection, the cylinder can be pierced by sharp objects, and if dropped the steel protector may fail causing the valve to break resulting in a sudden release of highly flammable LPG under high pressure.

Always have your cylinders refilled by an approved LPG dealer/vendor, never attempt to refill them yourselves.

The steel cylinder will corrode when exposed to damp conditions or water, and so if the cylinder has a rusted appearance it should not be used unless checked by an approved LPG dealer/vendor that is safe to reuse.

LPG cylinders must never be stored inside a house or building and must always be kept outside. LPG cylinders must never be exposed to direct sunlight and need to be stored under a sunshade. Strong sunlight will overheat cylinder and the internal pressure will significantly increase, and in some circumstances cause the cylinder safety valve to operate resulting in the release of large quantities of highly flammable LPG.

The correct procedure for replacing an empty LPG cylinder is as follows:

Removing an empty cylinder…

a. Turn off all control valves on your LPG appliance

b. Turn off the valve on the LPG cylinder

c. Using the correct size wrench, carefully undo the nut on the pipe coupling

d. Remove the pipe coupling and with your finger check the condition of the synthetic rubber ‘O’ ring seal. If the seal is damaged replace before reusing the coupling

e. Remove the LPG cylinder

Installing a full cylinder…

a. Put the LPG cylinder in position and remove the dust cap (if provided)

b. Carefully reinstall the pipe coupling finger tight making sure the threads are properly aligned, and then tighten the nut on the pipe coupling with the correct size wrench. Do not over tighten or damage the nut

c. Prepare a mixture of soap or washing up liquid in some water, turn on the LPG cylinder valve fully open, and using a brush or rag cover the nut, regulator and surrounding pipework with the soapy solution. If no bubbles are observed the LPG appliance is ready to use. However, if bubbles appear there is a gas leak, turn off the cylinder valve and investigate the cause. Repeat the process and if the leak persists, have a qualified and experienced plumber to inspect the problem.

When transporting empty or refilled LPG cylinders, they should be in an upright position and must be securely tied down to ensure they do not roll around and get damaged. Check that the valve is firmly turned off before putting the LPG cylinder into a vehicle, and no smoking during any part of the journey.

Smaller quantities of LPG is available in Camping Gaz (Gas) Cartridges, the hazards are same for the larger cylinders, except the cartridge is constructed from aluminum alloy. This means the cartridge can be more easily punctured by sharp objects and has less resistance to heat during a fire or from strong sunlight.

LPG can be stored in larger quantities than in a cylinder, such as bulk storage tanks, but the entire installation must be designed, installed and operated in accordance with NFPA 54 [National Fuel Gas Code]. This is beyond the scope of the normal user and this must be handled by an LPG specialist mechanical engineer.

5. LPG – appliances and devices

LPG appliances and devices are available in many different types and sizes. They range from barbecue grills, ovens and space heaters around the home, to camping gas burners and lanterns, to the larger ovens used in bakeries and restaurants, as well as many industrial uses and manufacturing.

LPG appliances and devices are only completely safe when the gas is turned off at the cylinder valve. Just turning off the control valve on the appliance may appear to be safe, but the pipework from the cylinder to the appliance is still full of flammable gas. So it is advisable to TURN OFF the gas using the cylinder valve whenever the LPG appliance or device is not in use, especially at night.

Medium to large size LPG appliances are equipped with safety features, which include an electronic push button igniter and a flame failure device called a thermocouple that detects the presence of gas flame and turns off the gas supply should the flame be blown out.

Smaller devices like camping gas burners and lanterns are attached directly to the small Gaz canister, and so the cylinder valve and the device control valve are one and the same. However, they are not equipped with an igniter or a safety flame failure device.

Whatever the design or type of LPG appliances and devices they must be supervised at all times when there is a flame present, this significantly reduces the fire risk, and should the flame blow out, the user can quickly turn of the gas to avoid the formation of an explosive mixture forming in the area.

All LPG appliances visually checked before EACH USE for defects and must be cleaned and cared for in accordance with the manufacturer’s instructions. At least once per year, or as recommended manufacturer (whichever is the sooner), all LPG appliances should be inspected/maintained by a qualified and experienced LPG Technician.

6. LPG – external use

LPG barbecues, cooking devices/grills, and space heaters produce large quantities of heat, and great care is needed to avoid an outbreak of fire, NEVER place them under enclosed porches/canopies or trees, near buildings, tents, bushes and vegetation, vehicles, trash cans, or any combustible materials. NEVER place a LPG barbecue or cooking device/grill on a combustible surface.

In high winds or heavy rain the LPG burner may be blown out, and so AVOID using LPG appliances and devices during bad weather conditions.

7. LPG – internal use

LPG cooking devices/grills and space heaters are very dangerous to use inside a house or building unless proper safety precautions are in place. As described earlier, without an adequate supply of fresh air LPG devices can produce deadly carbon monoxide gas, which is one-and-a-half times heavier than air and so it sinks to the lowest part of the room. You cannot smell carbon monoxide, it is colorless and tasteless and so the best defense is to stop carbon monoxide being produced by ensuring adequate ventilation. Accordingly, sleeping accommodation should be placed on the floor above the LPG device, or if the building is single story, horizontally as far away as possible.

Adequate ventilation means for a small to medium sized room, a fresh air vent 100 sq-cm to the outside just above floor level [lower vent], and an exhaust vent 100 sq-cm at ceiling height [upper vent], also to the outside. The fresh air vent and the exhaust vent should to be on opposite walls, but if this is not possible, separated by more than 45 deg and the two vents should NEVER be vertically aligned one above the other. For larger rooms the vent sizes need to 125 sq-cm or larger. A room with no vent or a single vent should NEVER be used for LPG devices. Always have TWO VENTS minimum, one lower level and the other upper level, this will provide proper cross-ventilation and will help prevent the production of dangerous carbon monoxide. The room containing the LPG device should always have at least ONE openable window to provide emergency ventilation.

The upper vent in kitchens for LPG cooking devices/grills can be substituted with a proprietary exhaust hood with an electric fan, but the exhaust outlet pipe MUST go to the outside and the lower vent and the exhaust hood must separated by more than 45 deg. Re-circulatory type proprietary exhaust hoods are NOT suitable for LPG applications.

It is a good idea to fit a battery operated carbon dioxide detector, which is UL Listed/FM approved/CE, they are relatively inexpensive and can save lives by quickly warning users that dangerous levels of carbon dioxide are present. The testing, maintenance and care of carbon dioxide detectors must be in accordance with the manufacturer’s instructions.

LPG cooking devices/grills, and space heaters produce large quantities of heat and so to avoid the risk of fire, they MUST NEVER be placed near to furniture, curtain drapes, closets, and other combustible materials, etc.

REFERENCE

Update: 20-Jan-2016

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