Global’s “Premium-Blend” Type 1 Blending System
In 2006 Global Ground Support introduced and patented the new “Premium-Blend”system. This revolutionary system allows customers to achieve the glycol savings achieved by low cost blending systems while eliminating and/or reducing all of the negative aspects of previous in-truck blending designs. The difference is the addition of a 3rd or “Blend” tank to the deicing system. The Global system blends the fluid into a third tank and then heats the blended water and glycol with a specially designed 3.4 million BTU heater. Global’s Type 1 Premium-Blend system uses a centrifugal pump to move fluid from the blending tank though the heater and out of the nozzle or returns it back to the blend tank. The return line does two things. If the blend of the fluid changes it allows all of the fluid in the entire system (blend tank, heater, pumps, hoses & nozzle) to be adjusted in less than a minute. It also keeps the fluid circulating through the heater, pumps & hoses (to the enclosed cab nozzle) so that the fluid at the nozzle is always at 180 degrees, providing the maximum allowable thermal benefits. Other systems allow the fluid in the boom hoses to cool off when not spraying. The anti-icing system (Type IV) has an independent tank and pump for both the Pro-Mix and Premium-Blend systems.
Changing deicing fluid / water ratio
There are two systems, Manual and Automatic.
The operator or supervisor (the system can be password protected) chooses the glycol percentage on the control panel. There are 5% increments 10%-60%. The system remains at that percentage until the operator selects an alternative or the system purges as part of the automatic shut-down procedure.
There is a temperature sensor on the boom that records the OAT (Outside Air Temperature) and the onboard computer determines the appropriate blending percentage. The customer will determine the buffer between the freeze point of the de-icing fluid and the OAT. The FAA & Transport Canada require a 10°C or 18°F buffer. Some airlines require a higher buffer, some in Europe a lower buffer. When the computer determines that a temperature change requires a glycol percentage change it takes less than 1 minute for the entire system to change to the new blend percentage.
In either the Manual or Automatic systems the initial mixture is created by two accurate positive displacement pumps. Each rotation of the pump produces a specific quantity of fluid. The computer controls the two pumps and both fluids are pumped into the blend tank to produce the required mix. An in-line refractometer verifies the mixture in the blend tank. This in-line refractometer also works with the computer management system to add glycol or water to maintain the exact percentage blend selected. This design allows for an accuracy of +/-2%, which is several times better than any other system available today.
The purge process of the Premium-Blend deicer is the systems biggest advantage compared with other blending deicers. During normal operation the blend tank is filled to 40% capacity. The remaining 60% provides capacity if the operator changes blends without spraying and also for the purging process. When the operator has finished using the deicer and shuts it down the computer will ask if he is ready to purge the system and start a countdown from 10. If the operator ignores the system, or just walks away from the truck, the computer will purge the entire system, blend tank, heater, pumps & hoses (tank to nozzle) with a 50/50 blend before allowing the truck to shut off. If the operator answers yes to the purge question it will ask what percentage he would like to purge the system to. If is going to be a mild night (20f) they might purge to a 30% mix. The purge process adds neat fluid to the blend tank, that mixture is pumped through the pumps, heater and boom lines, through the return line from the cab, back to the water line. The main water line from the water tank has an electric valve that shuts off during the purge process. The return line from the boom joins this pipe just under the valve and all of the water in the line & pump is purged into the blend tank. After purging the system the only place that is not freeze protected fluid is the water tank. The water tank is insulated and has thermal loss of 1 degree/hour. The water tank can be drained or plugged in and heated with immersion heaters for long term storage. If water is left in the tank an alarm (Klaxon & Beacon) is available to warn that the tank is >40f.