Fast Fill and Time Fill at CNG Stations

At CNG stations, filling is carried out by two different methods depending on how long the vehicle takes to fill. This distinction directly affects the choice of equipment at the station and the requirements on the dispenser side.

Fast Fill

Fast fill is the method in which the vehicle is filled within a few minutes. It is the closest to the familiar experience at a fuel station: the driver pulls in, fills up and continues on their way.

In this method the gas is stored already compressed and is transferred to the vehicle at a high flow rate during filling. Public stations serving urban roads and intercity routes generally work with a fast fill CNG dispenser.

Time Fill

Time fill is the method in which the vehicle is filled over a long period, mostly during the night. The compressor is connected directly to the vehicle and filling is completed over a number of hours.

This method suits fleets whose vehicles return to the same place at the end of the day. Municipal vehicles, shuttle fleets and commercial vehicles returning to a depot are examples of this use.

Differences Between the Two Methods

In fast fill what matters is time; how many vehicles the station can serve during busy hours is important. In time fill what matters is the number of vehicles and how long they are parked.

A difference arises on the equipment side as well. At a station carrying out fast filling the dispenser is a point of sale that works together with measurement and payment systems. In time fill, filling is generally carried out directly over the lines.

Passenger Vehicles and Heavy Vehicles

There is also a distinction in CNG filling according to vehicle type. Passenger vehicles and heavy vehicles are filled with different filling heads; these heads, named NGV1 and NGV2, are designed for different pressure and flow conditions.

In heavy vehicle filling, additional applications such as automatic grounding, filling pressure monitoring, emergency shutdown and heat monitoring come into consideration.

What to Consider When Setting Up a Station

The choice of filling method is made according to the profile of the vehicles to be served. If a public station is being set up, fast fill is considered; if a facility is being set up to serve an own fleet, time fill or a combination of the two is evaluated.

In both cases the equipment needs to hold the relevant certificates and to comply with the legislation of the country where the station is located.

For detailed information about CNG dispensers you can look at our CNG Dispenser page, and if you would like to discuss a suitable solution for your station you can reach us through our contact page.

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