General Deicing Concepts FAQ

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1 Bounce and Scatter Bounce and scatter is used to describe a product s ability to stay where it has been applied. If you think about dumping a bunch of marbles on a table, very few will actually stay on the table; they will bounce and roll away. The same thing happens when salt or sand is applied to the road, leading to over application to compensate for the product that is lost off the table. Liquid deicing and treated dry products can be used to minimize this issue. Flowability Flowability can be effected by many things. The three main causes of flowability issues are freezing, caking, and bridging. All of these issues are usually caused by moisture getting into a stockpile due to humidity, rain, or product treatment. This moisture can then freeze in cold weather, or dissolve some of the salt which then reforms in a crust of salt crystals. These crusts can grow up to several feet thick and can be a major waste of time, product, and money. Additionally, bridging is effected by gradation and shape on the salt. If a salt rock is too big or too sticky it will block the flow of the pile. These issues can be minimized by storing product indoors, covering with tarps, or adding anti-caking agents. If a customer is having these issues, please obtain their exact product formulation and procedure for storage so that we may pinpoint the problem. Corrosion Corrosion in general is caused by the oxidation of metals, specifically iron. It can occur with just water alone, but the process is expedited by salt solutions. When discussing corrosion in terms of PNS standard, one is referring to the corrosion of mild steel, which effects infrastructure NOT vehicles. For a product to be corrosion inhibited, it must have a PNS score below 30. When talking about the corrosion of vehicles, one is dealing with the corrosion of aluminum, chrome, and other metals. This corrosion can be avoided if the customer washes their vehicle soon after driving through product. The salt is highly water soluble and will come off if washed soon after. Dilution Factor When determining a products performance, one must consider what is happening on the road during a storm. The product begins to melt snow and ice, creating more water which the product is dissolved in. This water from the melting of snow/ice dilutes the product, lowering the concentration of solids in solution. The dilution makes the product less effective (now it has a lower % solids) and can cause it to refreeze or become ineffective. 1

2 Effective Temperature Most companies report the eutectic temperature or freeze point as the effective temperature of their products. Though this information can be useful, it does not accurately depict real world conditions. As mentioned above, the dilution factor effects the freeze point of the product. This discrepancy is the reason EnviroTech reports the 1:1 freeze point of our products as the effective temperature. By diluting the product 50% with water, we can simulate how it will behave after being diluted on the road. There- fore, the 1:1 freeze point relates better to the actual performance on the road, and gives the customer a more realistic idea of when the product will begin to refreeze. Why Wet? Liquid products and dry products treated with liquid start the brining process faster. It is actually the salt dissolved in the water (brine) that supplies the melting power of the deicer. The faster a salt can brine, the faster it will begin to melt things. However, when using just a brine the product will get diluted down faster (initial concentration being 30% vs. 100% dry), meaning the liquid version will work faster but not as long. (PLEASE NOTE: different salts have different melting capacities so some liquids will work all around better than dries.) This benefit can also be applied by treating dry salt with a liquid deicer, thus giving the product a little more speed but keeping the longevity of the dry product. Furthermore, treating dry salt also reduces bounce and scatter, can reduce corrosion, and can increase flowability of the product. Again, this all depends on salts used; some salts make crusting worse, some salts are incompatible with each other, etc. The same benefits can be applied to treated sand. The caution with sand is over-application of product. If the product is over applied, the sand may be too powerful and burn through the ice which then refreezes. If this occurs, the sand will be under the ice, and won t give the sandpaper effect that is desired for traction. Fallout Fallout in products is created due to formation of molecules that are insoluble in the product and/or at low temperatures. This can be caused by contamination from incompatible products or a drop in temperatures. Fallout issues can be avoided if the tank is cleaned regularly to remove traces of old material and/or residual build up from previous years. Most fallout is soluble in water and can be removed by rinsing out the tank. PLEASE NOTE: fallout is inherent in all products and all companies. If a customer is experiencing fall out issues, please get specific details of tank cleaning schedule, previous products in the tank, temperatures, etc. Send a sample to the lab of both the fallout and the liquid product. Explaining why this happened and how the customer can avoid it in the future is often a sufficient solution. 2

3 A Word on Storm Conditions Not all winter storms are created equal. Depending on temperature and humidity, snow and ice can behave very differently. When storms are cold and dry, the snow flakes are usually small and not as sticky. If there are strong winds, the snow will blow on and off the road. If it s warmer and wetter, you get big snowflakes that stick to the road. Usually, storms get colder as they progress, because the snow flakes remove moisture from the air. In terms of products, wet products work better against dry storms, and dry products work better against wet storms. If you recall that the brining process must start to melt snow and ice, this inverse relationship makes sense. When the snow is dry, you need the moisture of the liquid products to help start brining. If it is very cold out, you also need to be aware of potential freezing of liquid products, and usually MgCl2 or CaCl2 are used for this reason. In wet storms, the snow contains water and dry products can be used. In this case, dry products are preferred since they will not dilute down as fast in the wet snow/freezing rain as liquid products would. Furthermore, in warm storms refreezing is less of an issue. Often times, pretreatment with salt brine is done before warm storms since it won t compromise the friction on the road and there is no refreezing concerns at higher temperatures. To anti-ice in colder storms, liquid MgCl2 and CaCl2 can be used, but only after precipitation has started so that friction is not compromised. Brine Conc. 1:1 Freeze Point (ºF) MgCl 2 29% solids 4 CaCl 2 32% solids 7 NaCl 23% solids 17 Pavement/Surface Damage A common question asked by customers is will this product cause damage to the sidewalk or their deck or some different type of surface. For pavements, bricks, and the like, the damage comes from freeze/thaw cycles. As the snow melts, it fills in holes, cracks, and imperfections in the material. Then, when it refreezes, it expands and forces the cracks apart. Therefore, if the customer wishes to avoid damage, they should attempt to minimize the amount of freeze/thaw cycles the surface is exposed to. This can be done by using an adequate amount of product to prevent refreeze. Be aware, it is hard to control freeze/thaw cycles, and all deicers will damage surfaces in this way. When dealing with wood or composite materials, freeze/thaw cycles won t damage the material as much due to its flexibility. However, most deicers will dry out these surfaces, which can lead to further maintenance. 3

4 Specific Gravity Specific gravity is the ratio of the density (mass/volume) of a substance compared to the density of a reference substance. In our line of work, the reference substance is always water, which has a specific gravity of 1 (1 ml of water weighs 1 gram). Therefore, in order to determine the specific gravity of a sample, all one has to do is weigh a known volume of liquid. Then, the grams of weight is divided by the ml of volume, and you have the specific gravity. Example: 50 ml of MgCl2 weighs 64.5 grams. To determine the specific gravity you just take 64.5 g/ 50 ml and you get The specific gravity relates to the concentration of solids in solution, because the solids in solution are what change the density of the solution. This correlation is not intuitive (29% solids does not always give a specific gravity of 1.29), but is direct, in the sense that the higher the specific gravity the higher the solids concentration. This is why we use specific gravity to determine whether our products are the correct concentration. We normally use a hydrometer, which is easier than trying to get an exact volume of liquid. A hydrometer is calibrated to water, so that it will float at different levels in solutions with different specific gravities. The line on the hydrometer that reaches the top of the solution indicates the specific gravity of the solution, giving us an easy and quick way to read the specific gravity of our samples. Concentration Calculation A lot of times when dealing with liquid products, concentration becomes a big factor. The ability to get higher % solids will make a product work better when applied to the roads. Percent solids is defined as the weight of solids dissolved divided by the total weight of solution: For example: How many grams of NaCl are in 250 grams of 23% salt brine? How many grams of water? We know 250 g = total weight and % solids= 23, so we plug it in. Since we know this solution only consists of salt and water, the weight of the water is 250g total- 57.5g NaCl=192.5 g of water. Now suppose we mix up a 1000 gram solution of 90:10 23% NaCl:32% CaCl2. Now what percent solids are in solution? First, you have to calculate the amount of solids NaCl in solution: 4

5 Then, you can do the same thing to calculate the amount of CaCl2 solids in solution, and you should get 28.8 g of CaCl2. Now, you just add them together and divide by the total weight of solution: EnvorTech s Deicing Product Suite Preview Liquids: Meltdown 30% MgCl 2 Brine Meltdown Apex 30% MgCl 2 Brine plus performance enhancer and corrosion inhibitor; PNS score <30 Meltdown Inhibited corrosion inhibited 30% MgCl 2 brine; PNS score <30 32% CaCl 2 Brine SOS/SOS-C liquid MgCl 2 /CaCl 2 additive for wetting rock salt/sand Apogee low/non-chloride deicer Solids: IceSlicer Natural NaCl deposits; Redmond Minerals Meltdown Near Zero NaCl based solid product Natures Best/Pink Heat treated NaCl based solid product Safe Step MgCl 2 hexahydrate based product 5