KNOW YOUR ABC FROM CNG

What’s different about CNG against other gases which are in use currently?
In the past, gas-fuelled automobiles used LPG (Burshane). Today it is compressed natural gas (CNG) that is in use. Methane is the prime component of CNG while LPG is a blend of propane, butane and some other chemicals.

Can an existing LPG vehicle run on CNG?
An LPG-fuelled vehicle will not run on CNG as the two fuels are different from each other, have differing calcrific values and need different air-fuel ratios for combustion. CNG has to be stored at relatively higher pressure in a cylinder than LPG, so the same cylinder cannot be used for both gases. A vehicle will need specific conversion for CNG operation.

Will my car still run on petrol if I run out of CNG?
The petrol carburettor is retained during conversion for CNG so that the vehicle will still run on petrol. A switch on the dashboard allows one to make instant changes of fuel sources.

How much will I save on CNG?
Savings on fuel cost by using CNG will depend on size and fuel consumption characteristics of the vehicle, as well as mileage. As we have seen in the CNG Omni the cost per kilometre incurred was nearly half that of the costs incurred by the petrol van.

Should I use petrol occasionally?
Occasional use of petrol serves to lubricate the carburettor besides making for better running of the engine.

Is the CNG option safe?
Four key features make CNG a safer fuel than petrol, diesel or LPG. With specific gravity of 0.587, it is lighter than air so in case of leaks, it rises up and dissipates into air. (Other fuels form puddles on the ground in case of leaks.) CNG has a 700 degree Centigrade ignition temperature compared to 455 degree Centigrade for petrol. The range of 4 to 14 per cent in which CNG mixes with air by volume for combustion is small. Storage is far safer than for petrol, as CNG cylinders are designed and built from special materials and to high safety specifications.

What is the pressure of CNG in a cylinder?
CNG is filled to a maximum of 200kg/cm (about 3000psi/g) in a cylinder.

Is refuelling cylinders a safe option with such high pressures involved? Is it safe even in an accident?
Refuelling is safe as the cylinder is made from a single piece of special steel alloy, with no welded joints, and each cylinder is tested as per international specifications before being installed. A ‘burst’ disc ensures safety as in case of inadvertent high pressure filling, or fore, the disc ruptures so no excess pressure situation over the specified level is created. Italy, New Zealand, Argentina and the US are countries where CNG has been in use for years, and it has been categorised as being safer fuel than petrol.

Will CNG harm my engine in any way?
Use of CNG serves to extend life of lubricating oil as CNG will not contaminate or dilute crankcase oil. Fouling of plugs is eliminated and plug life is enhanced as CNG does not contain any lead. CNG enters the engine as gas while petrol comes in as spray or mist which washes down the lubricating oil from the piston ring area to raise the rate of engine depreciation. This reduces maintenance costs and engine life goes up.

Why are exhaust gases literally non-existent in CNG vehicles?
A major positive aspect of CNG use is that being a natural gas (methane content) its exhaust emissions contain just water vapour and minuscule quantity of carbon monoxide, no carbon or other particles. Being virtually pollution free CNG driven vehicles meet the most stringent of emission standards worldwide.

How does a CNG vehicle compare to a petrol powered one on performance parameters?
Easy starts, steady idling and smooth acceleration are virtues of CNG run vehicles. Power loss of 5-15 per cent means that acceleration is slower, which can be eradicated with spot-on tuning of the CNG kit, by advancing spark timing to derive benefit of its high octane rating. However the power loss is less than noticeable in city driving.

Does CNG equipment require special service?
The CNG kit is easy to service and durable to boot. For optimum efficiency regular checks, every 10,000km, are prescribed.

Can diesel vehicles be converted to CNG?
Yes, diesel vehicles can be converted to CNG and most public transport in metros which previously ran on diesel now use CNG.

Has the CNG movement fared well in developed or developing countries?
Having been around since the 1920s, Italy has 240 stations and 300,000 cars running on CNG, New Zealand has 250 CNG pumps and 250,000 vehicles. Argentina has undertaken a major CNG programme and has 700,000 CNG run vehicles. Thailand, Indonesia, Bangladesh, Canada, France, Pakistan, India, Holland, Australia, UK and the US have also taken to CNG in smaller measure. Availability of natural gas and socio-economic conditions are the two factors conducive to bring about switch to CNG fuel.

How does a country benefit if CNG were to be used on a large scale?
A country can have cleaner environment with comprehensive use of CNG, while new job opportunities and economy are other benefits of using CNG. Motorists will have to pay lesser for fuel and certain countries like India which has huge reserves of CNG can also export it to generate revenue. This will also reduce the expense of fuels we have to import.