What is an Anticontaminating System?
>> In spite of the Friendly Environmental properties of the Natural Gas, they could be improved, and this is the way to do it.
>> This System reduces emissions from the CNG combustion.
>> This System “looks after“ your engine

How does it work? It is a close loop system. The natural gas flow, is regulated with a valve droved by a stepper motor. The valve position depends on the oxygen concentration in the exhaust gases. This concentration is measured by a sensor called “Lambda Sensor” or “Oxygen Sensor”, which is located in the exhaust pipe.The lambda sensor signal is analyzed in the Control Unit, which, taking into account the engine load, drives the valve to the optimum position.

Why does it protect my engine?
The Anticontaminating System target is to maintain the fuel mixture in its optimum point (Stoichiometric Mixture) . In this way the combustion chamber temperature will be maintained between safety limits.


Definitions :

Types of air – fuel mixture
Stoichiometric Mixture :
Molecules of fuel react with air, exactly with the oxygen contained in it. When every molecule of fuel is combined with every molecule of oxygen, that is means that there is no free fuel or air, the mixture is called “Stoichiometric”. When we are working with CNG, the air – fuel ratio is 16,5 parts of air for every part of natural gas. For petrol combustion the ratio is 14,7:1.

Rich Mixture :
When the natural gas concentration is major than the ideal one, it will exist free fuel in the exhaust gases. When this occurs the mixture is called “Rich”.

Lean Mixture:
When the fuel concentration in the air – fuel mixture is minor than the stoichiometric one, the mixture is called “Lean”. This is a very dangerous situation for the engine. In one hand we have low fuel consumption, but on the other hand it raises the combustion temperature. Moreover, the engine will produce a large concentration of nitrogen oxide. To sum up, the temperature could reach dangerous values that could damage the engine.

Lambda Sensor
Air concentration in exhaust gases is measured by the lambda sensor. This device sends to the Control Unit an analogical signal which vary between 0 – 1 Volts (generally). For lean mixtures, voltage range will be between 0 to 0.5 Volts, rich mixtures will be between 0.5 to 1 Volts. These sensors are located in the exhaust pipe before the catalytic converter. Any fuel injection systems have more than one sensor, one after the catalytic converter and another one after it. The first one senses mixture condition.