Cooling water

Very often, it is a combination of a change in the mixture ratio (e.g., dilution due to refilling) and hydraulic deviations at the operating point. Both can impair cooling and cause the system to overheat.

Because minimum water flow rates and pressure conditions must be maintained, and the resulting power consumption at the operating point determines how efficiently the system runs.

An energy-saving circuit consisting of hydraulically active components and speed control: Once activated, the pump adjusts its output, the water flow rate stabilizes at the setpoint within a few seconds, and safety functions remain unaffected.

Cooling water is usually water used as a heat transfer fluid in the cooling circuit. Coolant refers to the liquid used, including additives—such as inhibitors or antifreeze—that enhance certain properties, such as freeze resistance or protective effects. Corrosion protection is important because water, in combination with oxygen, temperature fluctuations, and different materials, can promote corrosion. Appropriate additives stabilize the medium and reduce the risk of corrosion-related damage.

Distilled water can be useful when a specific water quality is required—for example, when preparing a mixture of concentrate and water to ensure that the properties are reproducible. In some systems, however, treated or pure water may be a better fit because it is specifically adjusted depending on the design. It is always crucial that water quality, additives, and materials are compatible—otherwise, corrosion can occur despite “clean” water, or the protective effect in the cooling system may deteriorate.

A low coolant level often manifests itself indirectly: rising temperatures, fluctuating cooling performance, or frequent topping off. If there is too little coolant in the cooling system, heat cannot be dissipated as effectively—which increases the risk of overheating. In addition, the water pump may not operate properly (e.g., drawing in air), which further reduces the flow rate in the circuit. Therefore, the level, refill volumes, and temperature trends should be regularly checked and documented.

Coolant loss is often caused by leaks in gaskets, flanges, or heat exchangers, by evaporation (especially in open systems), or by a drop in pressure in the closed circuit. A systematic approach provides immediate relief: identify the cause, document the amount of coolant added, and check whether this alters the mixture. Especially with coolant mixtures, it is important to restore the correct mixing ratio so that cooling remains stable and additives/corrosion inhibitors are not diluted too much.

For freeze protection, an antifreeze solution—usually a water-glycol mixture—is typically used, either pre-mixed or as a concentrate to be diluted. The mixing ratio is critical because it determines the freeze resistance and the physical properties of the fluid. Only the correct mixture protects the system at low temperatures without unnecessarily compromising cooling performance. It is also important that additives and corrosion inhibitors are compatible with the system so that the antifreeze does not create new corrosion risks.

The water pump determines how much coolant flows through the cooling circuit per unit of time—and thus how reliably heat is dissipated. At high temperatures, a stable flow rate is particularly important because even small deviations can lead to temperature spikes. At the same time, pressure and flow rate must be matched to the operating point: too little pressure can impair the cooling system’s performance, while excessive reserves consume unnecessary energy. Demand-based control ensures that the cooling system remains stable and that critical components—such as those near the engine and seals—are protected before overheating can cause damage.