Water is the root cause of corrosion in engines, eating away pumps, radiators, liners, etc. Current antifreeze formulations regularly fail to prevent corrosion.
Evans waterless coolants prevent water-caused corrosion in a cooling system.
The Evans Coolant Solution
Evans waterless coolants contain little oxygen and are comparatively poor conductors in comparison to water-based antifreeze, so metal corrosion and coolant degradation is eliminated.
The Science of Corrosion
When heated, water releases a significant amount of dissolved oxygen, but as it cools it reabsorbs fresh oxygen. This cycle leads to the corrosion of metal, which is accentuated in classic vehicles with no expansion chamber.
Water also acts as an electrolyte if dissolved solids—such as hardness salts (lime scale)—are present. This promotes galvanic corrosion, a process in which two metals corrode at different rates, often causing pitting.
Corrosion inhibitor formulations have changed many times over the years, but not always for the better. Nitrite, silicate, borate and azole-based products have been around for many years, with Organic Acid Technology (OAT) inhibitors appearing more recently. OAT formulations are often branded as “long-life” based on their five-year lifespan, compared with one to two years for standard antifreeze formulations.
Although OAT-EG-water mixtures are now used in most new car engines, they have proven less successful in older vehicles and heavy-duty diesel engines (HDDE). After several years of trying OAT-based products, many HDDE OEMs and fleet operators reverted to nitrite and/or Hybrid OAT (HOAT) formulations. One reason for this U-turn was that OAT formulations offer little protection against liner pitting.
To maintain effective inhibitor levels it is often necessary to retro-dose with Supplemental Coolant Additives or SCAs. It is common for SCAs to be under- or overdosed, leading to accelerated corrosion rates, cylinder liner pitting or the blocking of radiator channels with congealed inhibitor.
Most experts agree that water-based antifreeze is just as flammable as antifreeze concentrate under the right conditions. Timothy C. Finley is a Vehicular Forensic Reconstruction Specialist. His research has helped fire departments, police, and insurance companies determine what caused a fire. When Mr. Finley was asked about the flammability of antifreeze his response was as follows:
“As a forensic investigator of vehicle fires for nearly twenty years, the question of flammability of coolant has arisen many times and has been the issue of a number of lawsuits in the past. In the mid 80’s I observed a number of vehicle fires whose causes could only be explained by the ignition of engine coolant. At that time, there was no data available on the subject. I therefore chose to conduct testing to determine if pure antifreeze or antifreeze mixed with water in a 50% solution (coolant) would ignite or burn. I found that both would auto-ignite (ignite outside the presence of a spark or flame) on a hot surface. Surface temperatures of 650 degrees F to 750 degrees F would cause auto-ignition. Vapors at lower temperatures would ignite from a spark or flame. Heat sources containing more mass facilitated the auto-ignition process. I have repeated this testing a number of times over the years.”
From: Engine Coolant is it Flammable? Garret Engineers
Evans Advantage of a Low System Pressure:
A positive benefit that Evans Coolant provides as it relates to flammability comes from the reduced system pressure associated with the use of waterless coolants. Unlike their water-based antifreeze counterparts, waterless coolants operate with minimal system pressure, meaning that if the cooling system were compromised, hot coolant would not violently erupt, as would be the case with typically pressurized water-based coolant. If the leak were just a pinhole, there would be no atomized spray, as would be the case if the pressure were at typical water-based coolant values.
The vapor pressure of 50/50 weight percent EG and water mixture at 230F: 838 mm Hg
The vapor pressure of an Evans Waterless Coolant at 230F: 24.6 mm Hg
Based on third party flash point testing and years of anecdotal experience, waterless coolants present no more danger as it relates to flammability than water-based coolants under the same conditions. At its core, Evans Cooling Systems, Inc. is a technology based company whose goal is to produce products that are safe, effective and that provide a real benefit to the end user.
As water flows through an engine cooling system, it is subjected to many obstacles and constrictions. The resulting turbulence creates rapid changes in pressure, forcing small pockets of water to vaporise into “cavitation bubbles.”
As the pressure inside the system changes, the bubbles collapse with enough force to punch holes in the surrounding metal. The resulting “pitting” is a common cause of erosion—sometimes to the point of catastrophic liner failure. A similar form of cavitation-erosion can occur inside pump chambers (volumes) and the associated impellers. Pump and impeller erosion results in reduced coolant flow rates and an increase in overheating.
Evans waterless coolants have a boiling point above 191°C, which means they are far less likely to vaporise when subjected to turbulent pressure changes.
In a 250-hour engine dynamometer test, developed to determine the ability of various coolants to resist engine cylinder liner cavitation erosion, waterless coolants were shown to reduce pitting by 70%.
Water turns into steam at 100°C. Mixing traditional ethylene glycol antifreeze with water in a 50-50 ratio increases the boiling point to 106°C, which is close to the operating temperature of an engine.
Evans waterless coolants have a boiling point of over 191°C, far above the operating temperature of the engine. The high boiling point ensures that the coolant remains liquid at all times, enabling consistently effective cooling.
The Science of Overheating
Since the 1930s, engine coolants have been based on a mixture of ethylene glycol, water and corrosion inhibitors. All such mixtures have inherent physical and chemical limitations that restrict engine performance and affect reliability.
Traditional water-based antifreeze regularly crosses from efficient nucleate boiling, where the vapor finds liquid coolant cold enough to condense it, to a vapor insulating condition, where the liquid coolant is not cool enough to condense the vapor and a pocket of vapor forms that insulates the hot metal from the liquid coolant. Compared to liquid coolant, water vapor conducts heat very poorly, about 94% worse. The hot metal gets hotter, making a “hot spot” that causes detonation issues. Evans coolants avoid vapor insulating conditions because any vapor condenses immediately into liquid coolant.
This overheating and excessive thermal stress leads to several problems, including:
- Distortion of the cylinder head and liners
- Pre-ignition (engine knock) in carbureted engines
- Reduced combustion efficiency and detonation issues in fuel-injected engines
- Erosion caused by pitting around the liner, cylinder head and coolant pump
- Boil-over during operation and after-boil when the engine is stopped
Industry sources state that overheating is the most common cause of engine down-time and responsible for more than 40% of catastrophic engine failures.
About Pressurized Caps
Using a pressurised radiator cap can raise the system pressure and thus the coolant boiling point. A typical 1 Bar (14.5psi) pressure cap theoretically raises the boiling point of 50-50 coolant to 122°C, which you would expect to be sufficient to prevent boiling. In reality, pressure drops within the cooling system combined with very high metal temperatures adjacent to the combustion zone often result in boiling coolant and the formation of steam-vapor pockets. Once a steam-vapor pocket is formed, it will not readily condense and can lead to full-overheat, piston-liner scuffing, cylinder head warping and eventually total engine failure.
One of the most-asked questions we get at Evans is regarding how waterless coolant prevents cooling system-damaging electrolysis.
Evans Cooling Systems (ECS) has always contended that the absence of water in a cooling system dramatically reduces the likelihood of electrolysis-related issues in the cooling systems.
What is electrolysis?
Electrolysis damage in an engine cooling system is caused by unintended electrical currents that flow from voltage differences that exist in the engine coolant jacket, the radiator, and the heater core. The damage can include rapid corrosion, pitting, flaking, and pinholes. The voltage differences may result from poorly grounded electrical equipment that has a stray voltage problem.
Another source of cooling system voltages is from the action of dissimilar metals with which the coolant is in contact. Metals and alloys that are different from each other have different electrode potentials. When two of them come into contact in an electrolyte, one acts as a cathode and the other as an anode. The engine coolant is the electrolyte. The metals need not be physically touching, as the engine coolant is the conductive path for an ionic transfer. The ionic transfer causes erosion and pitting of metal, or electrolysis damage.
This is how Evans alleviates or prevents electrolysis problems:
Regardless of the source of the voltage differences, the amount of current flow determines the damage potential. The conductivity of the coolant is directly related to the rate of ionic transfer. It is measured in microsiemans per cm (μS/cm). Coolant that is 50% water has an electrical conductivity of about 3000 μS/cm. In contrast, Evans waterless coolants typically measure just 700 μS/cm. The substantially reduced electrical conductivity of the Evans coolant sharply reduces incidents of electrolysis.
NO WATER PRESSURE
As it heats, water generates high vapour pressures that exert internal stress on cooling system components. When the engine cools, the pressure reduces. This repetitive process often leads to fatigue and component failure.
Because Evans waterless coolants have a boiling point of above 191°C and will not vaporise within the cooling system, they generate such low vapour pressure that you can remove the radiator or expansion bottle cap while the engine is running.
This pressure reduction eliminates internal stress on hoses, pump seals and radiator seams, thus extending operating life by many years and preventing breakdowns.
FLAMMABILITY OF ENGINE COOLANTS
Evans is occasionally asked how the flammability of Evans Waterless Coolants compares with the flammability of conventional antifreeze mixtures that are generally half glycol and half water. On balance, Evans Waterless Coolants are not more fire-prone than standard water-based antifreezes.
When one researches the causes of vehicle fires, there are these conclusions:
- Neither antifreeze concentrate (without water) nor water-glycol antifreeze coolant is likely to be a first-fuel in a vehicle fire, but both can be ignited.
- Many factors have to be just right for ethylene glycol (EG) to be ignited, and it is unlikely that all of the factors present in laboratory tests will be present in a vehicle to enable combustion to occur.
- “Ideal” conditions are present in a laboratory when the flash points or fire point of liquids are determined and one needs to be careful in extrapolating the results to vehicle situations.
- One of the most important conclusions drawn by forensic investigators of vehicle fires is: Ethylene glycol coolants will not auto-ignite on the metal surfaces in a motor vehicle and cause a vehicle fire, except under very specific and unlikely conditions.
- For ignition to happen under non-ideal conditions, the hot surface metal temperatures for auto-ignition to occur (one mode of ignition) need to be higher than would be present under normal engine operation.
- In some instances, the temperatures need to be higher than even those seen in malfunctioning engines and in vehicles in which the engine has been overloaded for an extended period of time.
- Ignition of EG by a vehicle’s electrical system is unlikely because of the very specific circumstances that must exist.
- Although the presence of water in water-based antifreeze may provide some small measure of a quenching effect on an open flame, the water portion is generally short lived, as it is quickly vaporised and what remains is primarily glycol, which can ignite.