Water cooled compressors require little demand from your facility's ventilation system. This is because cooling water removes approximately 90% of the heat energy created by the electric motor.

An open system without circulating water requires an external source. This includes municipal water mains, lakes, streams, or well water. After passing through the compressor, this water is discharged.

When using this method, the system needs a thermostat control to maintain desired air temperature and govern water consumption. Generally, an open system is easy and inexpensive to install. However, it's costly to run, especially if the cooling water comes from water mains.

Water from a lake or stream is typically free, but needs filtration and purification to limit the risk of clogging the cooling system. Furthermore, water rich in lime may result in boiler scale forming inside the coolers - causing impaired cooling. The same concerns apply to salt water, which may be used if the system is designed properly and dimensioned accordingly.

In an open system with circulating water, cooling water from the compressor is re-cooled in an open cooling tower. This process involves air blown through a chamber. As a result, part of the water evaporates. The remaining water is cooled to 2˚C below the ambient temperature (depending on external factors including humidity).

Open systems with circulating water are primarily used when the availability of an external water supply is limited. The disadvantage of this system is that the water gradually becomes contaminated by surrounding air. In addition, the system must be continuously filled up using external water due to evaporation.

Another downside is that dissolvable salts are deposited on the compressor's hot metal surfaces, reducing the cooling tower's heat transfer capacity. Also, the water needs regular analysis and chemical treatment to avoid algae growth.

During winter, when the compressor is not operating, it's important to drain or heat the water to prevent freezing.

In a closed cooling system, water continuously circulates between the compressor and an external heat exchanger. This heat exchanger is, in turn, cooled by either an external water circuit or surrounding air.

When a water circuit cools water, a flat plate heat exchanger is used. With surrounding air, a cooling matrix consisting of pipes and cooling fins is used. The surrounding air is forced to circulate through the pipes and fins by means of one or more fans. This method is suitable if the availability of cooling water is limited.

The cooling capacity of open or closed circuits is about the same. That is, the compressor water becomes cooled to 5 °C above the coolant temperature. If surrounding air cools the water, you'll need antifreeze (e.g. glycol).

The closed cooling water system is filled with pure, softened water. With glycol, the compressor system's water flow must be recalculated. The type and concentration of glycol affects the water's thermal capacity and viscosity.

It is also important to thoroughly clean the system before it's filled for the first time. A correctly implemented closed water system requires minimal supervision and low maintenance costs.

For installations where the available cooling water is potentially corrosive, the cooler should be designed in a corrosion-resistant material such as Incoloy.

As referenced in the introduction, most modern compressor packages are also available in an air-cooled version. This setup involves forced ventilation inside the air compressor.

As a result, higher energy is consumed due to constantly running a fan. However, air-cooled compressors tend to be cleaner with fewer contaminants running through your equipment.

We hope this article helps you understand which type of air compressor cooling method is most appropriate for your setup, application, and needs. If you require additional insight, our team is happy to help. Please feel free to get in touch today to receive custom tailored advice.

In an open system without circulating water, water cooling is ensured through an external source: municipal water mains, lake, stream, or well and after passing through the compressor, this water is discharged as wastewater. The system should be controlled by a thermostat, to maintain the desired air temperature as well as to govern water consumption. Generally, an open system is easy and inexpensive to install, but expensive to run, especially if the cooling water is taken from the municipal water mains. Water from a lake or stream is normally free of charge, but must be filtered and purified to limit the risk of clogging the water cooling system. Furthermore, water that is rich in lime can result in boiler scale forming inside the coolers, and causing gradually impaired cooling. The same applies to salt water, which may however be used if the system is designed properly and dimensioned accordingly.

In an open system with circulating water, cooling water from the compressor is re-cooled in an open cooling tower. Water is cooled in the cooling tower by allowing it to sprinkle down into a chamber as surrounding air is blown through. As a result, part of the water evaporates and the remaining water is cooled to 2˚C below the ambient temperature (this may vary depending on the temperature and relative humidity). Open systems with circulating water are primarily used when the availability of an external water supply is limited. The disadvantage to this system is that the water gradually becomes contaminated by the surrounding air. The system must be continuously diluted using external water due to evaporation. Dissolvable salts are deposited on the hot metal surfaces, reducing the thermal heat transfer capacity of the cooling tower. The air water cooling system must be regularly analyzed and treated with chemicals to avoid algae growth in the water. During winter, when the compressor is not operating, the cooling tower must either be drained or the water must be heated to prevent freezing.

In a closed water cooling system, the same water continuously circulates between the compressor and some form of external heat exchanger. This heat exchanger is in turn cooled either by means of an external water circuit or by the surrounding air. When the water is cooled using another water circuit, a flat plate heat exchanger is used. When the water is cooled using the surrounding air, a cooling matrix consisting of pipes and cooling fins is used. The surrounding air is forced to circulate through the pipes and fins by means of one or more fans. This method is suitable if the availability of cooling water is limited. The water cooling capacity of open or closed circuits is about the same, i.e. the compressor water is cooled to 5°C above the coolant temperature. If the cooling water is cooled by the surrounding air, the addition of an anti-freeze (e.g. glycol) is required. The closed cooling water system is filled with pure, softened water. When glycol is added, the compressor system's water flow must be recalculated, as the type and concentration of glycol affects the water's thermal capacity and viscosity. It is also important that the entire system be thoroughly cleaned before being filled for the first time. A correctly implemented air water cooling system requires very little supervision and has low maintenance costs. For installations in which the available cooling water is potentially corrosive, the cooler should be designed in a corrosion-resistant material such as Incoloy.

Most modern compressor packages are also available in an air-cooled version, whereby the forced ventilation inside the air compressor package contains close to 100% of the energy consumed by the electric motor.