Eliminate spillage and tank pressure. Achieve high-speed, top refuelling.

C2G’s FillGuard protects against pressurising non-viscous liquid storage tanks during filling and prevents their over-filling.

The C2G FillGuard is a mechanical device that works on the principles of Hydraulic Differential and Fluid Dynamics. It is a top filling, self venting device designed to adequately fill shallow large volume tanks typical of Diesel powered water pumps, generators, lighting towers and locomotives.

The benefits, previously not achievable with other types of overfill devices, ensure failsafe operation where spillage is eliminated while ensuring tanks are filled to capacity.

USAGE

DRY BREAK WITH AUTO SHUTOFF

The Device is typically used in conjunction with Dry Break Refuelling equipment that has the facility to control dispensing with automatic shutoff capability. Incorporating the Device into the refuelling system equipment ensures fuel tanks are not over pressurised during refuelling or when full level is reached.

TOP FILLING

Top Filling ensures differential pressure variations from the increasing liquid height in the fuel tank, inherent with bottom filling systems, are eliminated leaving the differential pressure constant throughout the refuelling process.

OPERATION

The C2G FILL GUARD device works using a differential in pressure on the two faces of the Piston. During filling the incoming liquid flow causes the Piston to move down in the Body to the point where the spring tension plus cavity pressure below the Piston is equal to the pressure on the top surface of the Piston. This pressure equilibrium only operates while the Chamber has a small amount of free flowing liquid passing in and out at the same time. When filling is in progress and the liquid level is below the Float Assembly a small amount of liquid bleeds out from the bottom of the Chamber past the open jet seat, which maintains a decreased cavity pressure and allows the Piston to push down against its spring and remain in the open position. The restrained open condition is approximately 3kPa which is low enough to keep refuelling nozzles from shutting down prematurely. When liquid lifts the Float Assembly, the Jet closes preventing any further liquid from bleeding out of the Cavity. This causes an increased pressure in the Cavity and imbalances the pressure differential across the Piston which allows enough force for the Piston to move up towards a closed condition. There is not sufficient power from this action to cause complete hydraulic lock but sufficient to cause the refuelling nozzle to close. This increased pressure differential is >18 kPa.

In order to cause a complete hydraulic lock, a unique reverse acting Lower Piston mechanism has been introduced. This concept applies all the flow (pump) pressure used during refuelling to be applied to sealing the jet thus preventing weeping of fluid/pressure in the piston cavity. By introducing the reverse acting hydraulic lock power this provides 99% positive force to the main liquid ports closing off liquid flow and preventing any further liquid from entering the tank. The operator could attempt to open the refuelling nozzle but it is then impossible to add more fuel until the fuel tank level falls below the float assembly level.

The Cavity dimensions cause it to develop a sufficient hydraulic force when the float/Jetassembly has closed to push the Piston toward the entry port. The Piston is restrained by a circlip at the point where the Body main liquid ports have closed preventing any further liquid from entering the tank.

When the fuel tank level lowers, the needle Jet will drop under gravity as the float drops. There are sufficient exit ports in the Hydraulic Chamber body to release the stored hydraulic energy after the nozzle is disconnected and the tank fuel level falls. The hydraulic stored energy remains while the fuel tank level is “Full”. Full Level is typically 40mm from the top of the tank but this may be less depending on flow rates and tank volumes.