Sun. Jun 20th, 2021

City gas distribution

Transporting future fuel

#51 CNG Dispenser

3 min read

The purpose of a dispenser is to dispense the CNG to vehicles and recording the volume of gas dispensed. The CNG dispenser is a stand-alone unit that consists of an enclosure where the measurement and regulation devices are located. The refueling procedure can be done by receiving the natural gas directly from the compression unit or through the cascade.

The four hose dispenser could be used for simultaneously filling bus/truck on one side and car on the other side. Depending on which type of nozzle switch is pressed the corresponding valve will be switched to the right hose. The dispenser is available in the single hose, double hose, four hose, and automatic dispenser.

The dispensing pressure can’t be higher than 220 bar at the refueling stations in which the compression is realized at a pressure higher than 220 bar, the pipeline to the dispenser is equipped with a device that limits the pressure to a valve of 220 bars. It also has to be insured with proper equipment, that the maximum established pressure does not exceed the set pressure. For this purpose, after the compression unit at the beginning of the pipelines that deliver the natural gas to the dispensing units, besides the principal equipment of reduction of the pressure, a safety device is installed. This acts before the pressure overcome the maximum established value of set pressure. At the refueling stations in which the compression is realized at pressures higher than 220 bar, the pipeline to the dispenser is equipped with devices for the automatic cut off of the compressors as the pressure becomes higher than 220 bar.

The emergency shutdown system is activated by an emergency button, manually operated, and located near the local panel of the compressor or near the refueling area and at the station main office. This system performs:

i) The total isolation of the pipeline to the dispensing units through the valve.

ii) The total isolation of the low-pressure pipeline from the inlet of the compressor.

iii) The total deactivation of all the electrical circuits, with the exception of the ones necessary for the safety system.

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