[SIZE=3]2. The Smell of Stenching agent
can remain on your hands after filling for a very long time, even if you washed them once or twice. Also note that the smell of any released gas can 'hang' for days on any item it has contacted, if not washed away. A good example of this is a faulty vaporiser that we removed from a car but did not throw away. 6 months later it still Smelled of gas. This persistent smell can also result in unwarranted concern. [/SIZE]
[SIZE=3]LPG 'Leakdown'.[/SIZE]
[SIZE=3]Vehicles with single point mixer systems -[/SIZE]
[SIZE=3]When the vehicle's engine is switched off from gas operation, some gas will naturally be present in the induction system and remain unused. The gas is heavier than air and will tend to 'sink' to the lowest level possible. If the pipe from the inlet manifold (where the gas mixer is often sited) is sloping downward the remaining gas will seep down into the air filter and may well escape to atmosphere, resulting in the smell. [/SIZE]
[SIZE=3]This effect is called 'Gas leakdown'. It is not a dangerous condition as the gas is in low concentration, further reducing as it mixes with the surrounding air. The next time the engine is started, no gas will leak down as it is drawn into the engine, but the next time it is stopped identical condtions will arise and the smell may reappear. It would not be unreasonable for a driver to imagine that the smell is present when the car is running, giving the impression that the system is leaking all of the time. [/SIZE]
[SIZE=3]Leakdown may be further complicated. I have seen at least one car (Ford Granada Mk 3) where the sinking gas was able to find its way into the intake of the fresh air system. The car's ventilator fan had been left on to demist the screen, but then turned off with the ignition. The next time the engine was started (on gas or petrol) the fan came into operation and the gas effectively stored in the fresh air duct was blown into the car. (The cure for this would be to resite the fan's air intake away from leakdown.)[/SIZE]
[SIZE=3]Curing leakdown......[/SIZE]
[SIZE=3]There is a cure for leakdown, but sadly most customers press for the cheapest conversion possible and it is not included in their system.[/SIZE]
[SIZE=3]A timer device is available which wires into the car's ignition system and the gas solenoids. When the ignition is turned off, the gas is turned off by cutting power to the solenoids, but the engine will continue to run until all the gas present in the induction system is used up. No smell of gas can then occur as no leakdown is possible. Simple, effective, but almost universally ignored.[/SIZE]

[SIZE=3]There is a cheap alternative cure which is to always switch back to Petrol and allow the engine to idle for a minute or so before stopping it. No gas can then be left in the induction system and leakdown is zero.[/SIZE]
[SIZE=3]Multi Point Gas Injection Systems[/SIZE]
[SIZE=3]These can also display leakdown, but to a much lesser extent. There is far less gas in a shorter length of the induction system. As a result, the potential for leakdown is greatly reduced and often goes unnnoticed altogether.[/SIZE]
[SIZE=3]Conclusions [/SIZE]
[SIZE=3]1. Most reported'Smells of Gas' are not dangerous, and do not indicate that there is a problem with the gas system or its installation.[/SIZE]
[SIZE=3]Other factors can be to blame......[/SIZE]
[SIZE=3]An owner of a car converted elswhere complained that his car smelled of gas every time he filled the tank up. A long investigation was carried out but no leak or cause was found. Only when the customer later mentioned that he could smell gas when he filled his other vehicle up with Diesel did the penny drop....[/SIZE]
[SIZE=3]This Customer used the same gloves to fill his first vehicle with LPG and the second with Diesel.
The smell of gas was on the gloves.....[/SIZE]
[SIZE=3]2. In the case of leakdown the effect can be cured by asking the installer to fit timed shutdown equipment or the driver simply making sure than the engine is always run down on Petrol for at least one minute before stopping it.[/SIZE]
[SIZE=3]Some other facts [/SIZE]
[SIZE=3]People running Petrol cars have become accustomed to a slight smell of Petrol being present if the bonnet is opened. Likewise, those running Diesels are not the slightest bit surprised if they smell Diesel when they open the bonnet. Both are most likely to be the effect of fuel 'leakdown' from the induction system but are ignored as being normal.[/SIZE]
[SIZE=3]However, if the vehicle is converted to run on LPG, a new smell of gas (actually the 'Stenching Agent') can cause great alarm, but indicate no increase in risk. [/SIZE]
[SIZE=3]And finally...... Don't be TOO comforted by this explanation and ignore ALL 'Smells of Gas'! [/SIZE]
[SIZE=3] If you think you may have a leak, DO go and get it checked out (we'll do it for free) and make sure no serious condition exists. [/SIZE]
[SIZE=3]Just be a slightly more ready to accept that sometimes a whiff or two of gas smell does not indicate that your gas system has been badly fitted by your installer, nor that it is in a dangerous condition now. [/SIZE]
[SIZE=3]
lifted it from here

http://www.go-lpg.co.uk/

Mga BMW, Saab, Volvo, Mercedes, etc nagpapa LPG din pala.
[/SIZE]