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Liquid separator & cooling

How a liquid separator works

Some of the liquid will be released with the exhaust air. It is therefore necessary to add sealant liquid during operation. To achieve best results while minimizing costs, we recommend fitting a liquid separator to all our pumps. Beside collecting and recycling the operating liquid, a liquid separator will ensure correct pump intake pressure.

A liquid separator is fitted with a service liquid valve to ensure correct liquid level. When the service liquid valve is connected to the water supply, it will replace any evaporated liquid. As the liquid level is above the level of the pump, it is necessary to close the supply of liquid to the pump when it is not running. We have therefore developed a special valve specifically for this purpose. The service liquid valve is opened by the pilot pressure created by the liquid ring in the pump. There is therefore no requirement for external control.


The sealant liquid heats up during operation, so a method of cooling the liquid is therefore often required. Our product range offers three different cooling solutions.

1. Partial recirculation

Cooling by partial recirculation is achieved by replacing part of the service liquid. A temperature regulating valve ensures that the required amount of water is fed to the liquid separator. The excess hot water flows out of an overflow pipe. The amount of water consumed depends on the selected water temperature and water supply temperature. Typically, the amount of water added is between 10 and 20% of the total water flow.

2. Heat exchanger

In instances where access to external cooling water is available, water consumption can be reduced to a few liters per hour. The operating liquid for the pump is fed through a heat exchanger where it is cooled before being fed back into the pump. A temperature regulating valve ensures the correct flow of cooling water for the required temperature

3. Air cooling

Cooling sealant liquid with the aid of an air cooler also minimizes water consumption. The operating temperature is generally slightly higher than that of the above solutions (typically around 20 øC above the ambient temperature). As the air cooler is sensitive to impurities, the unit includes two cooling circuits.

The hot sealant liquid is fed through a heat exchanger, where it is cooled by the water from the air cooler. This means that any impurities drawn through the liquid ring vacuum pump will not be fed through the air cooler