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�cwof •wayiic GIIy111CG1 illy + c— o—ai ice• i� wayic ,.,oi crvu-• Ti �u � /00:7.7UO+M o 2.4. THE BLENDING PROCESS A blender has two grades of fuel (product) input to the dispenser. These two grades are the LO and HI product inputs referred to as "feedstocks." The proportional blending dispenser uses the feedstock input grades to deliver three to five grades (depending on model) outputs to the "nozzle;." T�vu of these grades are feed- stock*and the other one to three(depending on model)are a blend mixture of some propor- tion of the feedstock inputs. All grades are dispensed through the same hose and nozzle, see Figure 2-3. The fixed ratio blending dispenser uses the feedstock products to deliver three grade outputs to the "nozzles."Again, two of these three grades are the feedstock products,but unlike the proportional blender, the third grade or blended grade is delivered through a separate hose and nozzle. Also, the feedstock grades are each individually delivered through separate hoses and nozzles, see Figure 2-4. In all blending dispensers,there are two separate sets of hydraulics. One for controlling the LO octane product input and one for controlling the HI octane product input. In all enhanced Vista blending dispensers(1/V models),whether it's a proportional or fixed ratio blender, the LO and HI product hydraulic systems each contain a proportional now control valve. When any grade (LO, HI or blend) is selected, the blend ratio programmed into the dispensers computer determines the percentage or proportion of HI product to be dispensed. When the LO grade product is selected, the proportion or percentage of HI product is 0%. When the HI grade product is selected, the percentage of HI product is 100%, When a blended grade is selected, a percentage of HI product(less than 100%) is mixed with the remaining percentage of LO product, and the combined total(100%x)deter- mines the octane rating of the blended grade. Knowing the percentage or proportion of HI, and thus LO, product to dispense and by calculating the volume dispensed based on input signals from the pulsers, the computer signals the solenoid drive board which in turn controls the proportional flow control valves. Each proportional flow control valve continuously opens or closes, as directed by the sole- noid drive board,to maintain the desired blend ratio and the maximum allowable flow rate. * Some customer specific models may not dispense feedstocks.For example,one feedstock and four blended grades may be dispensed. The maximum allowable flow rate in the United States is 10 gallons per minute. 9 January 1997 Part No. 920160 Rev A