Compressed Natural Gas (CNG)

1. Compressed Natural Gas (CNG) is a fossil fuel substitute for gasoline (petrol), diesel, or propanefuel. Although its combustion does produce greenhouse gases, it is a more environmentally clean alternative to those fuels, and it is much safer than other fuels in the event of a spill (natural gas is lighter than air, and disperses quickly when released). • CNG is made by compressing natural gas (which is mainly composed of methane [CH4]), to less than 1% of its volume at atmospheric pressure

2. It is stored and distributed in hard containers, at a normal pressure of 200–220 bar (2900–3200 psi), usually in cylindrical or spherical shapes. CNG is used in traditional gasoline internal combustion engine cars that have been converted into bi-fuel vehicles (gasoline/CNG). -CNG cylinders can be made of steel, aluminum, or plastic. Lightweight composite cylinders are especially beneficial for vehicular use because they offer significant weight reductions when compared with earlier generation steel and aluminum cylinders, which leads to lower fuel consumption.

3. Comparison between natural gas and gasoline • Natural gas has two important benefits,that make it spread widely as afuel for SIE &modern CIE,one of them is its low coast combared with gasoline (1cubic meter,.45l.e, vs .95 litre gasoline,1 l.e),the other one is that natural considered clean more than gasoline.however there are some disadvantages for natural gas: • 1-sulfur content in N G is higher than it in gasoline (hot fuel). • 2-carbon content in NG is smaller than it in gasoline,carbon make athin layer in cylinder walls that decrease friction. • -so its better to start up car by gasoline then convert to natural gas. • 3-lower heating value in NG than gasoline(so torque &acceleration is less than it in case of gasoline.

4. KIT OF CONVERSION1-CNG CYLINDER. -It is an cylinder which contains gas and it is located at car back and fixed by metal belts and rod. -This cylinder has no welding joints. - their valves are three saftey valves to ensure that cylinder is safe , one of them is a thermal saftey that works when tempreture increases in cylinder ,a thin layer of pb(lead) melts , another one works when pressure increases and the last one is mechanical works by human force to close valve. -Also there are holes in car to make gas flow out the car if cylinder valve has aproblem.cylinder can withstand 300 bar.Heat treatment is made for its material to withstand impacts , high pressures.Its size differs by vechicle type.

5. 2-PIPE LINE • -Its a line that allows high compressed gas to transfer to regulator. 3-FILLING VALVE. It is a non-return valve which uses to fill cylinder with high compressed gas. -It has 3 holes one to enter gas , one for pipe line from cylinder and one for pipe line to regulator.

7. 4-PRESSURE GAUGE. • -it is a pressure gauge which fixed before regulator.it enable us to know pressure in cylinder and to know if it full or no. • -it has two types mechanical gauge and electrical gauge that needs a float.

8. 5- GAS REGULATOR: It is a regulator that regulates gas transfer to the mixer .This regulator consists of three stages of pressure drop.The pressure drops from 220 bar to 1 bar to make mixing process of air with gas.First stage reduces pressure from 220 bar to 4 bar , second stage is from 4 bar to 2 bar and final stage is from 2 bar to 1 bar. Regulator Components: 1-Gas Solenoid: it opens gas passage to regulator when petrol solenoid is closed.Also it closes gas passage when petrol solenoid is opened.there is a safety system to avoid pressure increase it is called a safety valve which opens automatically when pressure increases , and closes when pressure returns to safety position.

9. 2-MIXER. • -Gas exit from regulator to enter mixer to mix with air and be ready to burn. • -Mixer has avarious shapes depend on car type or carburetor type. • -Mixer fixed above carburetor under it is cover. • -some manifold has no blace for mixer.so we must make acomple. • -Comple:Apipe fixed in it to enter gas from regulator.

11. 5-SOLENOID OF PETROL. • -It locate between fuel pump and manifold to control petrol flow by electric signals from switch.

12. 6-SWITCH. • -Locate at the car in front of driver, • It enable driver to convert from petrol system to gas system easily be sending electric signals to solenoid petrol ordering it to close so petrol does not flow also order solenoid gas to open and let gas flow. • -switch have three or four small lamps to show if cylinder full,half full or going to emptey. • -All electric signals come from switch.

13. 7-FLOW ADJUSTER. • -Control percent of air mixing with gas.

14. -Look for suitable place to fix regulator. -Look for suitable place to fix filling valve. -Remove carburetor cover,put mixer and fix by metal part then cover.. # Note:if there is no mixer , open a hole in manifold and put compile. -Fix pressure gauge on its place at regulator entrance. -cut hot water line from engine and connect it by regulator hot water inlet.connect water exit to radiator. -install petrol solenoid between petrol pump and carburetor inlet. # For cylinder: -select available position for cylinder -Fix two belts at the top and buttom of car storage and ametal rod which carry cylinder. -Put cylinder on rod and link belts around it. *STEPS OF ASSEMBLY.

15. #for pipe line: -Pipe line comes from cng cylinder to regulator passes through car ground . -try to fix it at highest points as you can to avoid breaking,also pipe line near exhaust pipe must be insulated.

16. Electrical Connections Gas solenoid (blue+black)Gasoline solenoid(yellow+black)Air flow adjusturefloat(green+black+white)Ignition coil(brown)Contact(red)Ground(black)