Safety & Emissions


CNG, which is always a gas, is safer than traditional liquid fuels such as petrol and diesel for a number of reasons.

Firstly, in the event of a fuel leak, the gas will dissipate rapidly upwards whereas with liquid fuels they will pool on the ground creating a potential fire hazard.

Secondly, CNG has a much higher ignition temperature than liquid fuels (580 DegC as opposed to 220 DegC for petrol), therefore less potential ignition sources are likely to be present in the event of a gas leak.

Thirdly, CNG has a narrow range of flammability, igniting only when the concentration in air is between 5 and 15% (petrol is between 1 and 8% mix in air). Natural Gas is also non-toxic or corrosive and will not contaminate ground water. Natural gas combustion also produces no significant aldehydes or other air toxins, which are a concern in gasoline and some other alternative fuels.

Another safety feature that NGV’s have is that the storage cylinders both on the vehicles and at the refuelling stations are made from very strong material and are protected by pressure relief and other safety devices. The design of the cylinders is subject to a number of severe tests such as fire, collision, mechanical damage etc.

The refuelling process at the dispensing pump is also very safe as the whole system is “sealed” which prevents any leakage or spillage of product.

Safety and Hazardous Areas

Whenever you design a CNG refuelling station you must take into account the local and international rules that are applicable in that region or country. These will relate to the design, installation and operation of CNG refuelling stations and may differ from country to country.

In all cases you will need to do some sort of hazardous area analysis and a series of Risk Assessments, all of which will ensure that the equipment is installed and used in a safe manner.

Careful consideration needs to be given to the specifying of components within the hazardous area (the area defined as that which might contain a hazardous environment). Hazardous areas may have to be approximated at an early stage in a project to allow electrical equipment to be specified and other potential sources of ignition to be located. However, a definitive drawing should be produced prior to operation of the filling station and should be based on the appropriate standards for that region.

When embarking on a gas station project you would need to take many other legal and allied considerations into account, such as Consultation with appropriate enforcement bodies, legislative Law and Acts, Codes of Practices, and also the competency of the people designing, installing and operating the gas stations.

GCNGSL have extensive knowledge and experience in this field and would be able to assist in all these areas of responsibility.

All GCNGSL designed stations have many safety protection devices built into them including:

• Inlet Solenoid Valves

• Inlet Non-Return Valves

• Inlet Pulsation Vessels

• High & Low Pressure Switches

• Gas Inlet Filter

• Auto Drain Solenoid Valves

• Blow Down Vessel Return lines

• Gas Tight Oil Filler

• Vent Stack Manifold

• Compressor Delivery Non-Return Valve

• Starter Control Panel Pressure Switch

• Exd Marshalling Box

• IS Marshalling Box Acoustic and explosion proof enclosures

Environmental issues

There are many reasons why someone would want to invest in alternative fuels, the main drivers being; Environmental, Economical, Entrepreneurial and Technology Evolution.

Running vehicles on natural gas can reduce or eliminate:

• Lead and carbon monoxide levels of petrol engines

• Particulate emissions of diesel engines

• Noise levels of diesel engines

The reduction in harmful emissions can be significant:

• Carbon Dioxide – 22-24% reduction against petrol, 10% reduction against diesel

 Carbon Monoxide – 76% reduction against petrol, CNG & Diesel both low

• Nitrogen Oxides – 83% reduction against petrol, 80% reduction against diesel

• Hydrocarbon – 88% reduction against petrol, 80% reduction against diesel

• Benzene – 99% reduction against petrol, 97% reduction against diesel

• Lead – 100% reduction against petrol, not applicable for diesel

• Particulates – not applicable for petrol, Eliminated for diesel

• Sulphur – nearly 100% reduction against petrol, nearly 100% reduction against diesel

Natural Gas is slower burning than petrol or diesel resulting in reduced wear and increased engine life. There is no lead in natural gas therefore the lead fouling of spark plugs is eliminated and life extended by 2 to 3 times.

Other drivers:

Security of Supply – A country dependent on imported oil can provide some protection in the event of international oil crises by shifting to indigenous natural gas for its transport.

Improved resource utilisation – Countries are providing national support for NGV programmes because it provides good economic reasons to do so and substitutes an indigenous fuel such as oil.

Political & Social – CNG offers a serious reduction in harmful emissions and is a key driver in political decision making as well as being a key driver in meeting social change initiatives.

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