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Old 20th August 2007, 13:48   #1
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Default How safe are the CNG kits

Hi,

Today while I was going to office, I saw a Indica with smoke coming from under its bonnet.
The car stopped and suddenly the whole car started burning.





A bus stopped by and its driver tried killing the fire by pouring water but in vain.
With the help of certain people, the Indica's driver managed to get the CNG cylinder out from the car.
I shared this experience with my friends and they told me that they have heard of more such incidents where the cars being driven on CNG burnt down completely.
I am wondering if this is the case of unauthorised kits or some other vulnerabilities of the CNG kits.

Last edited by Sush : 20th August 2007 at 14:06. Reason: Added images of the burning car
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Old 20th August 2007, 18:20   #2
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It can be probably because of Local CNG kits. How cars catch fire still remain a mystery.
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Old 20th August 2007, 20:53   #3
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How he managed to remove the cylinder beats me..!!!

The cylinder is Bolted to the Body on a Fabricated Steel Frame, So in all likely hood, It might have been an Illegal LPG Cylinder Driven Indica.

CNG incase of the leak, dissipates quicker, Infact its Lighter than Air, So a Leakage should almost be Non Fatal compared with LPG being a Heavier Gas settles low.

How CNG cars catch fire,Beats Me- Have to yet see one with a Genuine Kit, Maintained with Periodic Checks Go Up in Flames..!

Mine is on 18514, with 1 Yr 2 Months on the Road with CNG, I keep a Routine Check, and No issues with Safety so far.

Even Then By Far there are a large number of CNG vehicles on Road, If this was Unsafe, I'm sure there would have been no Rush at all for Filling up.
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Old 20th August 2007, 21:06   #4
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If the fittings used are not good quality, gas can leak out of them...will readily ignite if you have an electrical spark caused by shorts.
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Old 21st August 2007, 01:32   #5
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I think the question we need to ask is how safe is CNG... compared to LPG, Petrol and Diesel.

And I think, it as safe or as unsafe.

All of the above can be ignited.... wrong place, wrong time = explosion!

From the limited knowledge that I have on the subject, compared to other fuels, I thought CNG requires alot of compression to ignite... therefore wont ignite so easily?

My 2 cents :P

Last edited by yuv : 21st August 2007 at 01:32. Reason: typo
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Old 21st August 2007, 10:26   #6
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I second this, well said wolf.

Quote:
Originally Posted by wolfinstein View Post
How he managed to remove the cylinder beats me..!!!

The cylinder is Bolted to the Body on a Fabricated Steel Frame, So in all likely hood, It might have been an Illegal LPG Cylinder Driven Indica.
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Old 21st August 2007, 10:28   #7
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Quote:
Originally Posted by wolfinstein View Post
CNG incase of the leak, dissipates quicker, Infact its Lighter than Air, So a Leakage should almost be Non Fatal compared with LPG being a Heavier Gas settles low.
CNG would be safer than LPG.

Similarly Diesel is safer than Petrol.

Quote:
Originally Posted by yuv View Post
I think the question we need to ask is how safe is CNG... compared to LPG, Petrol and Diesel.

And I think, it as safe or as unsafe.

All of the above can be ignited.... wrong place, wrong time = explosion!

From the limited knowledge that I have on the subject, compared to other fuels, I thought CNG requires alot of compression to ignite... therefore wont ignite so easily?

My 2 cents :P
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Old 21st August 2007, 17:16   #8
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Quote:
Originally Posted by dadu View Post
CNG would be safer than LPG.

Similarly Diesel is safer than Petrol.
Everything is absolutely safe as long as everyone follows the safety parameters !
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Old 22nd August 2007, 08:51   #9
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Frankly i am no expert in this CNG/LPG stuff, but a little googling on safety aspects of CNG vs LPG got me this:
Source: Auto Monitor
Quote:
From the safety perspective in automobiles, LPG is considered as safe as any conventional fuel. Authorities worldwide have successfully carried out several crash and fire tests on auto LPG. The pressure at which CNG (at 200 bars) and LPG (at 5-7 bars) is stored also makes LPG a better and safer option. Experts also said that owing to the strength and integrity of the fuel tank, LPG is safer than petrol and is on par with diesel.
Also, in our very own Team-BHP advice section topic by GTO(http://www.team-bhp.com/forum/modify...parision.html) (ARTICLE: CNG vs LPG Comparision), here is a summary of comparison of CNG v/s LPG.


While the first article declares LPG more safer, the second one says that CNG is "safe" but does not comment on the safety of LPG vis-a-vis CNG. I dont think ignition temperature can be the *only* parameter to gauge safety. Someone with more knowledge on this please enlighten.

Last edited by DCEite : 22nd August 2007 at 08:55.
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Old 22nd August 2007, 11:02   #10
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Guys,

Firstly, it is impossible to yank out the CNG tank. It is fitted securely as Wolf mentions.

You must remember that safety of tank/tubing installation might be equal - but the flammability of fuels differs. Hence, I'd downright disagree with the Automonitor link.

Then again, here are some more links to chew:
http://www.team-bhp.com/forum/techni...tml#post478307 (Leakage of LPG killed the driver?) - check the link quoted from the CPCB. They would surely know their fuels better than a media site.

http://www.team-bhp.com/forum/techni...tml#post477888 (Leakage of LPG killed the driver?)
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Old 25th August 2007, 00:29   #11
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The Other Criteria are-

Heavier Cylinder Make allows a Higher Protection against collisions,If I'm not wrong the Tanks can hold pressure under Impacts even upto 200 Bar.

Being a Lighter Gas ( Lighter than Air Itself), CNG will dissipate into the Air, LPG being Heavy will typically settle Low.

The Ignition Temp plays a Very Important part in Safety of CNG or LPG- CNG needs a Higher Ignition Temp comparitively to LPG, and then CNG also needs a Compression to ignite at room temp, unlike LPG which can ignite at room temp without compression.
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