2 General description
NGW 300 / LGW 300 / GBW 300
202
2.1
Combustion air fan
The combustion air fan forces the air necessary for com-
bustion from the combustion air inlet into the combustion
chamber. In addition, the necessary amount of gas is aspi-
rated from the fan by means of the gas pressure regulator.
The fan comprises an impellent and a rotor which are joi-
ned together by means of a coupling. The air is sucked in
via a protective grille in the hood and mixed with gas in the
mixer.
There is a special version for a combustion air intake ex-
tension which commits the combustion air to be taken in
by means of this extension.
2.2
Gas pressure regulator
Gas is supplied by means of the vehicle’s gas supply sy-
stem, in which the gas pressure regulator is incorporated.
Different types of regulators are utilised for operation with
CNG (natural gas) and LPG (propane).
In CNG gas pressure regulators, the gas pressure of the
system is regulated downward from a maximum of 220
bar of excess pressure in 3 steps to barely below at-
mospheric pressure. A safety valve protects the gas pres-
sure regulator in the event of a pressure surge.
In LPG gas pressure regulators, the gas pressure of the
system is regulated downward from a maximum of 30 bar
of excess pressure in 2 steps to barely below atmosphe-
ric pressure.
After the solenoids have opened, the required quantity of
gas is sucked out of the gas pressure regulator by the
combustion air fan through the gas suction hose. The re-
quired quantity of gas is released by a diaphragm valve
in the gas pressure regulator. This is dependent on the
cross-section of the gas intake nozzle and the negative
pressure in the gas suction pipe.
CNG gas pressure regulator (NGW 300)
LPG gas pressure regulator (LGW 300)
2.2.1 Heating the gas pressure regulator
As the expansion of the compressed gas causes considera-
ble cooling, the gas pressure regulator must be warmed up.
This is accomplished by integration into the cool water cir-
cuit. The flow rate is regulated by a thermostat valve.
At approximately 50 °C, the thermostat valve begins to re-
strict the flow rate and is in the final position at approxima-
tely 60°C. Further heating and regulation of the flow rate
are guaranteed by a leakage amount.
1 Gas outlet to the heater
2 Drain plug (oil)
3 Water inlet
4 Solenoid (2)
5 Gas inlet from the storage tank
6 Water outlet
4
4
5
3
6
1
2
1 Gas outlet to the heater
2 Solenoid (2)
3 Water outlet
4 Drain plug (oil)
5 Water inlet
6 Safety valve
7 Gas inlet from the storage tank
2
2
7
6
5
3
1
4
