Solid deicers are generally used as “deicers.” This means they are applied after snow and ice have fallen and bonded to the surface. Solids bore holes through the accumulated pack to the pavement as the deicer changes form from solid to liquid. Some solids like sodium acetate anhydrous actually give off heat (exothermic reaction) as they dissolve. It causes the solid to work faster than an endothermic product such as urea.
Solid deicers come in two forms, pellets and granules. Pelleted deicers are harder and therefore, are less dusty. And because of their even size they tend to spread more uniformly. Both deicers adhere to the surface and have less bounce during application when applied on wet or light snow covered surfaces.
Generally, anti-icing techniques are more efficient than deicing, because it requires far less energy to prevent a bond from forming than to break it. Think of holding two magnets close together but not joined. It takes little energy to keep them apart. But once the magnets are linked — like ice bonded to the pavement — it takes a lot of energy to break them apart. And so it is with anti-icing versus deicing techniques. Less chemical is required to prevent the bond than to break it. In a typical winter storm, both techniques may be necessary to provide safe working conditions.
Pavement surface temperature, ambient temperature and pavement chemical concentration levels are all variables that affect pavement refreeze. Refreezing occurs when ice control chemicals dilute sufficiently that the brine solution turns to ice. Monitoring the variables closely allows for timely reapplication before refreeze.
Sand use may cause friction levels to improve in the short term. However, sand has little long-term value in an on-going storm. There are also accompanying clean-up costs and a real concern for sand ingestion into airplane engines.
Choose the Right Application Equipment
Choosing the right deicer spreader and sprayer provides accurate, cost effective applications. Ground speed control, the right spray nozzle configuration and calibration are important for accurate chemical delivery. Spreader covers should be used to protect dry deicers.
Training Is Important
All the best chemicals and state-of-the-art equipment are useless if maintenance personnel do not know how to properly use them. Initial and refresher training for both anti-icing and deicing strategies are often provided by quality manufacturers.
Efficient, effective airport ice and snow control is clearly a difficult task particularly in raging winter storms. Yet timely movement of aircraft and safe working conditions are imperative for successful winter operations by airlines and other airport customers.
Maintenance personnel have a wide range of storm-fighting strategies available to them. Their “tool box” includes first the use of mechanical removal whenever that alone achieves desired friction levels. But when conditions are such that chemicals are required, only “airfield certified” deicer formulations should be used.
Good training before winter hits will help ensure the right anti-icing and deicing techniques are fully understood and effectively practiced. Field maintenance managers should look to their purchasing departments for qualified vendors, certified deicers and ample training to help ensure this most difficult task is managed correctly.
Clariant Corporation manufactures Runway and Aircraft Deicing/Anti-icing products. The SAFEWING Aircraft Deicing/Anti-icing fluids: Type I-Safeway MPI 1938 ECO Type III - Safewing MP III 2031 ECO...
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