Are LPG Cars Safer than Petrol? | Video
For some reason people are overly concerned with the safety of LPG cars.
What is truly amazing about this is that LPG autogas vehicles may actually be safer than petrol models.
Decades of Learning
LPG has been used safely in Australian vehicles for many decades.
Australian LPG fuel systems have evolved and constantly improved over that time.
Steel Not Plastic
Did you know that some new petrol cars come with plastic or composite fuel tanks?
Autogas tanks are typically made from welded heavy gauge steel.
The steel is generally 3mm to 6mm thick, depending on the tank design.
An LPG tank is designed to withstand many times its maximum operating pressure.
They are much more puncture resistant and will survive much greater impacts than a typical petrol (gasoline), ethanol or diesel tank.
The tank mounting systems are also designed to ensure that the tank will not become dislodged, even in a 20 G impact.
Autogas tanks are designed with an Automatic Fill Limiter (AFL) to prevent overfilling so the release of excess fuel during the refuelling process is virtually eliminated.
On the other hand, most of us have experienced petrol spills.
Also, unlike spilled petrol, which will puddle under your car, any LPG that might escape just dissipates into the air.
Pressure Relief Valves
Autogas tanks are designed to withstand even the most extreme conditions.
The tanks are designed with 20% unused volume to allow for any expansion of the LPG in hot conditions.
There is also a pressure relief valve that ensures that the internal tank pressure stays within safe tolerances, even when the tank may be exposed to an abnormal amount of heat.
Automatic Shut-off Systems
There are electronically controlled shut-off valves which stops the flow of gas to the engine if the engine stops for any reason.
Autogas engine fuel systems are also fitted with safety devices and excess flow shut-off valves that function automatically in an emergency.
Double back-check valves are used to ensure gas tight filling. This prevents any accidental backflow.
At least one of the non-return valves in the backflow prevention system is designed to still work even if there is damage to the external filling assembly as the result of an accident or other causes.
LPG is less likely to catch fire than petrol.
The autoignition temperature is the minimum temperature required to ignite a gas or vapour in air, without a spark or flame being present.
Petrol (gasoline) ignites at temperatures as low as 246°C while LPG (propane) ignites at 470°C.
So, petrol is more likely to catch fire in the event of exposure to a hot exhaust system.
The popular TV show, Fifth Gear, decided to test which fuel was safer in the event of a fuel system leak.
They simulated leaks that filled the car with fumes and then ignited it.
The result with LPG was a veritable flash in the pan compared to when petrol fumes destroyed the entire back of the test car. Enjoy the video:
Sealed Passenger Compartment
The venting around valves and pipe work is sealed to ensure no LPG enters the passenger compartment of the vehicle.
Should a leak occur, it would vent harmlessly outside the vehicle.
In addition, all lines and hoses are protected from loose cargo that could potentially cause damage.
This actually makes the Fifth Gear leak scenario highly improbable in a real life LPG car.
The Smell of Safety
LPG Autogas has a distinct odour which makes it very easy to detect any possible leaks.
Odourant is added to the LPG for this specific purpose.
Strict Australian Standards
Australian LPG Autogas safety standards have been refined over many years.
LPG fuel systems for vehicle engines are covered under Australian Standard AS 1425.
The Standard specifies the requirements for the design and construction of component parts and for their installation in vehicles, as well as for tests, commissioning, and periodic inspection.
This Standard defines the minimum requirements of acceptability.
The specifications and requirements of AS 1425 are some of the most stringent in the world.
Trained & Authorised Technicians and Certification
The mechanics that work on LPG vehicles are required to have more training than an ordinary car mechanic.
Specific schooling and knowledge, relating to Autogas systems, is a requirement.
All conversions also require certification. On completion of an aftermarket installation, the installer will supply a certificate of compliance with AS 1425.
They will also affix a compliance plate, containing relevant details, within the engine bay of the vehicle.
Same Insurance Premiums
The true testimonial for Autogas safety is the cost of insurance.
It costs no more to insure an LPG car than a petrol car.
Insurance companies are experts in risk assessment.
If LPG cars were more dangerous, you can be certain the insurance companies would be charging more to insure them.
Autogas is Safer for Your Wallet
Don’t forget that you can save a substantial amount of money with autogas.
Petrol can give your wallet “fuel anorexia”.
Owning an LPG vehicle and using autogas can help keep your wallet fit and happy.
You Be the Judge
So, are LPG cars safer than petrol models?
There are certainly features that would suggest that is the case. At the very least, they are just as safe.
Now that you know the facts, you can draw your own conclusions.
Are LPG Autogas Tanks Bulletproof, too?
If you were a police officer driving an LPG Autogas powered car, wouldn’t you want to know what happens when the fuel tank gets shot?
Well, that exactly what they set out to do in this test.
What could be more American than police officers shooting their guns?
Having them shoot their guns at something and trying to make it explode!
Who Shot at the Autogas Tank?
Alliance AutoGas is an American company that provides LPG conversions to fleet operators in the US, including police departments.
They teamed up with Force 911, a company that specialises in police vehicle equipment, to run this test.
Together, they organised for a bunch of local police to come out and shoot at an LPG Autogas tank in the back of a typical police car.
I doubt they took much persuading!
They even opened the boot and attached a bullseye on the tank to make it easier for them to hit it.
5 Different Types of Handguns
They started out shooting the tank with a .45 calibre automatic.
Then they tried .40 calibre, .38 calibre and 9mm handguns.
They also shot it with 3 guns simultaneously.
Finally, they pulled out the “heavy artillery” and shot it with a .357 Magnum.
The made a lot of small dents and chipped a lot of paint off the tank but never once punctured the tank or caused a leak.
The Petrol Tank Comparison
As a point of comparison, they fired a single .45 calibre shot into a petrol (gasoline) fuel tank.
As is the case with most modern petrol tanks, it was made from HDPE plastic.
The bullet not only punctured the tank, it went right through both sides.
Fortunately, the tank was completely empty or they may have gotten their explosion!
Out Comes the High Powered Rifle
They were determined to puncture the tank so they resorted to a high velocity, high powered .223 calibre rifle.
They finally succeeded in puncturing the tank and causing it to leak but got no fire and no explosion.
Why Didn’t it Burn or Explode When First Punctured?
LPG (propane) will only burn when the fuel to air ratio is between 2.15% and 9.6%.
Less than that is too lean and more than that is too rich.
The contents inside the LPG tank are liquid but only vapour ignites.
So, initially the vapour was either way too rich to ignite or the LPG was in its liquid state within the tank.
Knowing this, and determined to entertain everyone with at least a bit of fire, they waited for some of the gas to dissipate.
Once it got down to where they thought it was within the ignition range, they shot into the tank again.
WHOOSH! ...but NO BOOM!
That did it!
They finally got it to burn, but no explosion.
Contrary to what Hollywood would have you believe, the reality is that it is very hard to get an LPG tank or cylinder to explode.
It is indicative of the fact that LPG vehicle safety may even be better than petrol.
See the BOOM!!!
Want to see a fuel tank explosion?
Watch this short Fifth Gear video for an even more entertaining version of a similar experiment, including a petrol tank explosion... KABOOM!!!
Comments, questions or feedback?
The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.