Gas Detection in NGV Vehicles and Storage Sites

NGV Buses (Natural Gas for Vehicles) Market

NGV (or BioNGV) is becoming increasingly important in the storage of buses, trucks and dump trucks.
Natural Gas for vehicles can come in two different forms: in gaseous form called CNG (Compressed Natural Gas) and in liquid form called LNG (Liquefied Natural Gas). Although their forms are different, the purpose of CNG and LNG is the same. Biogas is also a part of these natural gases. They are considered biofuels. This means that if a bus, truck or other vehicle runs on NGV, it also has a tank for conventional fuel. If the natural gas tank runs out of fuel, gaseous fuel (gasoline or diesel) takes over from there. A normal vehicle can operate with NGV only by installing a specially designed tank.

Both the economic and ecological aspects of Natural Gas for Vehicles enable it to achieve significant growth in different communities (especially “city buses” and garbage trucks) and in the heavy vehicles sector. Indeed, it is a replacement fuel designed for use in urban vehicles, reducing air pollution and therefore the impact of transportation on the environment. Mainly methane (CH4) and a single carbon atom (C)
Having a base composition, NGV is the cleanest and least polluting hydrocarbon available for this type of vehicle. By comparison, the light hydrocarbons we know today, such as propane and butane, consist of 3 carbon atoms. For gasoline or diesel, there are up to ten carbon atoms, making them relatively polluting gases.

This natural fuel can be produced by two different methods. First, we find a fairly common technique: extraction from natural deposits underground. After doing this extraction by drilling and pumping the gas, it can be purified for transportation to its final destination (transportation via pipelines or methane tankers). The second process that can be used to obtain natural gas for vehicles is the methanization technique. It occurs by fermentation of waste products (vegetable, sanitary or food), followed by their mixing and gentle filtering, creating BioGNV, a completely biodegradable gas.

Composed of methane, it is a natural gas that we all encounter in our daily lives because it is the same gas we use to heat our homes or heat our stoves. Its use is simply diverted and modified for use as fuel.

More and more manufacturers and communities tend to invest in and use natural gas vehicles to stop the rise of air pollution. In fact, this fuel is known to emit 20% less CO2 (carbon dioxide) than other energies.

There are standards related to this energy transition, such as the Euro 6 anti-pollution standard, designed to limit harmful gas emissions and the carbon footprint of the mobility sector. Therefore, it is essential to encourage the use of renewable energies instead of polluting fossil fuels.
According to research by the International Gas Association, natural gas (NGV) is a fuel that has been growing at a rate of approximately 20% annually worldwide for the last 10 years.

Advantages

The positive impact of natural gas on the environment for vehicles and the reduction of toxic gas emissions it produces are not the only advantages that can be identified with its use.
Besides being virtually polluting, NGV vehicles have a host of other advantages.
First of all, buses and other NGV vehicles are quieter because the gas burns very slowly, and they are also more efficient. They also have greater autonomy thanks to the bi-fuel system (gasoline or diesel comes into play when the tank is empty). According to drivers, ride comfort and smoothness are remarkable compared to fuels usually used.
No toxic smoke or fine particles are emitted when using NGVs.

The last major advantage of using natural gas is related to its economic aspect. The use of natural fuel in the mobility sector extends the life of bus exhaust pipes by up to 3 times. In addition, the engine breaks down much less quickly and its lifespan is doubled. This is possible because NGVs are in gaseous state, which avoids all the difficulties that can occur with liquid fuels, for example the possibility of mixing with engine oil. Thus, the risk to the engine is significantly reduced.

Gas detection in NGV bus depots

Driving on dual fuel means taking double the risk. Indeed, it is necessary to prevent new risks associated with natural gases and to store equipped vehicles.

ATEX standards must be complied with

This type of fuel is still hazardous for storage as it is a flammable and explosive substance. It is therefore important to determine which regulations will be taken into account. In this case,  ATEX regulation (ATmosphères EXplosives) is essential for everyone's safety. This standard defines the areas where specific safety devices must be installed and the means of prevention in question. This
For the field of activity, ATEX standards apply to NGV storage stations but in certain cases also to maintenance workshops.

 

As a reminder, the ATEX regulation includes different categories. There are dusty areas (ATEX 20, 21 and 22) and areas with gas or vapor; and NGV bus depots are handled according to this category. Divided into 3 categories (1, 2 and 3):

  • Zone 0: Area where explosive gas/air (or dust) mixture is persistent or prolonged
  • Zone 1: Area where an explosive gas/air (or dust) mixture is likely to occur in normal plant operation (occasional risk)
  • Zone 2: Area where an explosive gas/air (or dust) mixture is unlikely to occur during normal plant operation (equipment failure)

Alan belirlendikten sonra, havalandırma , bir veya daha fazla gaz dedektörü veya acil kaçış ekipmanı gibi özel tesislerin yanı sıra net sinyallerle sınırlandırılmalıdır .

It is mandatory and essential to also comply with other standards, through the inspection of equipment and others, which allow to prevent risks for local residents and protect and preserve biodiversity.

Gas detection and preventive measures

When an ATEX zone is defined, the person responsible for the relevant business must take the following necessary measures:

As already mentioned, measures directly related to the storage of natural gas buses need to be implemented, for example, the installation of a gas detection system. This system will warn all teams about a malfunction (gas leak, fire start, …). To do this, there are different types of detectors to monitor temperature changes, gas leaks, pressure, gas concentration rates (carbon monoxide, natural gas).

Flame and gas detection devices such as the QUASAR 900 open path, Searchline Excel or specialized gas detectors such as the OLCT100, GD10P or SearchPoint Optima Plus for CH4 detection are recommended.

 

Finally, the European regulation ECE R110 states that periodic inspections of components of NGV vehicles are mandatory. The vehicle's compressed gas tanks need to be checked every 4 years and replaced every 20 years.