Cooling towers are an integral part of most large-scale cooling systems and are vital equipment for a variety of commercial, industrial and agricultural operations. As such, keeping your cooling towers well maintained and in good condition is vital, and one of the most persistent dangers to the condition of your cooling towers is rust.
The warm, moist interior of a cooling tower creates the perfect conditions for rust and corrosion to form, and preventing this damaging chemical reaction from taking metal cooling towers out of commission is a challenge faced by industries across the world. However, cooling tower is far from an inevitable occurrence, and there are a variety of ways you can inhibit the accumulation of rust in your towers.
Anti-rust coatings designed to protect metal cooling towers from corrosion are widely available, and they are made from durable epoxy resins -- applied as a liquid, they dry to form a tough 'skin' over the internal surface of a cooling tower. This skin is waterproof and prevents both moisture and air from reaching the vulnerable metal surface, dramatically inhibiting the formation of rust.
These coatings are very inexpensive and can be applied simply, using nothing more complicated than paintbrushes and rollers. As such, they are a great way to prevent your towers from rusting on a budget -- however, they do require occasional renewal to remain effective, and the cooling tower(s) in question must be deactivated and disassembled before the coating can be applied and left to dry. Anti-rust coatings can also be applied to the exterior surfaces of cooling towers to inhibit rust formation there, although exposure to wind and weather will cause them to wear away more quickly.
Corrosion inhibitor additives
These chemical compounds are added to the water supply of the cooling system your cooling towers serve, and they contain one or more chemical additives (such as orthophosphate or zinc) that inhibit corrosion. These additives remain present when the water turns to vapour and is expelled via your cooling towers, and the evaporated additives condense on the internal surface of the cooling tower, providing lasting protection for as long as the additives are used. This solution is inexpensive and effective, but it is most effective when combined with other rust inhibiting methods.
Water pH control
Besides adding corrosion inhibitors to your water, you should also take care to keep the pH of your cooling system's water tightly controlled. Allowing your water to become too acidic will cause corrosion to promulgate more rapidly, and frequent pH tests should be conducted on both your cooling system's water reservoir and inside the cooling tower itself. Water additives can be used to raise pH levels if they get too low, but be careful not to overdose them, as water that is too alkaline can promote the accumulation of scale on cooling vanes and other surfaces.