Refueling dispenser

Onboard Refueling Vapor Recovery (OR ) regulations were fust proposed m 1987 but were met with a litany of technical and safety issues that delayed the requirement. The 1990 CAA amendments required the implementation of ORVR and the EPA regulation requires passenger cars to first have the systems starting in 1998. The ORVR test will be performed in a SHED and will require that not more than 0.2 grams of hydrocarbon vapor per gallon of dispensed fuel be released from the vehicle. 

The use of LH2 for CGH2 supply is also possible. The hydrogen is transported to the filling station as LH2. During refuelling the LH2 is vaporised to supply CGH2. Furthermore, both LH2 and CGH2 can be dispensed. 

Canada s hydrogen transport and distribution infrastructure program comprises refuelling stations (various locations and various companies), and includes work on large-scale water electrolysers, hydrogen compressors up to 700 bar, hydrogen dispensers, controls, and codes and standards. 

Fast-fill CNG refueling systems need a dispenser to direct the CNG into the vehicles. Dispensers include a meter to measure the amount of the CNG that went into the vehicle and, for public refueling stations, the cost of that gas. In slow-fill systems, a hose and a connector is provided for each vehicle, and metering to determine the amount of CNG going into the vehicle is usually cost prohibitive. For this reason, slow-fill is usually considered practical only for vehicles of a single fleet. 

Dispensers for CNG provide a convenient means of directing CNG from the storage system into the vehicle. They will typically incorporate some sort of on-off switch activated by removal of the refueling nozzle and a meter to measure the amount of CNG dispensed. A typical CNG dispenser as used at commercial CNG refueling facilities is shown in Figure 4-7. 

CNG dispensing nozzles are made from aluminum and stainless steel and no materials compatibility problems have been noted. The mechanical action of fastening the CNG nozzle appears to be the limiting factor in CNG nozzle life, not deterioration due to corrosion from the natural gas. CNG dispensing nozzles have a finite lifetime typically characterized by the total number of refuelings completed. Nozzles should be replaced at the end of their useful life to prevent inadvertent failure. 

Like CNG dispensing nozzles, CNG dispensing hoses have finite lifetimes— often measured in the number of refuelings completed. When the lifetime of the hose has been exceeded, it should be replaced to prevent inadvertent failure during use. Hose manufacturers will have guidelines for determining when their hose should be replaced. 

The control systems for CNG refueling systems have evolved from being only mechanically controlled to some that are completely computer controlled today. Computer control offers flexibility not possible with mechanical systems and the ability to change the control strategy of the refueling system. Computer-controlled systems can also provide functions such as accounting of the amount of fuel dispensed into vehicles and billing functions. It is also possible to incorporate safety shut-down of the system if certain conditions are present. 

Figure 4-8 shows an LNG refueling facility designed for refueling LNG transit buses. This facility includes a dispenser, kiosk, canopy, methane detection system, fire suppression system, and trailer-mounted LNG storage tank. In this system, LNG is pumped from the storage tank to the dispenser and then on to the bus. A trailer-mounted tank was chosen for this application since a permanent tank was not desired. 

LNG dispenser hoses should have breakaway fittings to prevent a vehicle from pulling away from the dispenser with them attached. Since the LNG hoses are securely fastened to the vehicle when refueling, pulling away without disconnecting the hoses will cause the hoses to be severed or the dispenser to be damaged. 

Propane refueling systems do not need elaborate control systems. The dispenser controls operation of the transfer pump, and emergency shut-down switches should be mounted near the dispenser and at some location between 6.1 m (20 ft) and 30.5 m (100 ft) from the dispenser. 

Leak detection systems are not required for propane refueling systems but could be incorporated in the vicinity of the dispenser, near ground level since propane vapors are heavier than air. Like pipeline natural gas, propane is odorized so that leaks should be noticed by refueling personnel. 

NFPA 30A does not specify limits on the location of fuel dispensers except that they must be at least 6 m (20 ft) from any fixed source of ignition. Dispensers should be solidly mounted on a refueling island or some similar equivalent means. Protection should be provided in the form of bollards or guardrail to prevent errant vehicles from colliding with the dispenser. For above-ground tanks, dispensers can be mounted directly on the tanks. 

Dispensing hoses are limited to 5.5 m (18 ft) and must have a breakaway device in the event a vehicle drives off without removing the refueling nozzle. 

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