Why Fuel Pumps Don’t Cause An Explosion?

Most of us are aware how easily gasoline (petrol) ignites. Even the slightest of sparks can make gasoline go up in flames. You may have tried it on your own or seen it on screen. That’s why we are extra careful when handling gasoline. Even static electricity can create sparks that can ignite gasoline. Cellphones have also been blamed, although there is not enough evidence to link cell phones with gasoline fires. However, it does not harm to be extra cautious.

In view of such flammable nature of gasoline, it is quite shocking to know that electrical fuel pumps are located inside fuel tanks of various cars and two-wheelers. If the spark plug can ignite gasoline, why don’t fuel pumps do the same inside the gasoline tank? To understand why fuel pumps don’t cause an explosion inside gasoline fuel tanks, here are some important things to understand.

Air to gasoline ratio – While we have seen gasoline go up in violent flames, it cannot do so without oxygen. And the air to gasoline ratio must be within a very narrow range for the mixture to ignite. As per current standards, 14.7 grams of air will be needed to burn 1 gram of fuel in an optimal manner. So, the air to gasoline ratio for achieving combustion is 14.7:1. If there is more air, the resulting mixture will be a lean mixture. It won’t be able to ignite. If there is more fuel and less air, it will be a rich mixture. It too won’t ignite.

Inside the fuel tank, the electric fuel pump is submerged in gasoline. As there is no oxygen, the fuel will not catch fire even if there is spark created by the fuel pump. Even in the empty portion of the tank, much of it will be gasoline fumes. This is a rich mixture condition, which does not create a fire even if there is a spark. In essence, the inside of the fuel tank is the safest place to mount the fuel pump.

Brushless motor – Most modern cars and two-wheelers are equipped with brushless electric fuel pumps. These are less susceptible to generating sparks. This further reduces the probability of a fuel pump igniting the gasoline. Having said that, it is also true that even brushed motors are unlikely to cause the gasoline to catch fire.

As is evident from above, fuel pumps, irrespective of brushed or brushless, will not create fire even when there are sparks. Fires can occur only when there is a leak and the fuel comes in contact with outside air. Be rest assured that fuel pumps are completely safe and the possibility of fuel tanks exploding due to fuel pumps is unthinkable.