The temperature of the oil and water contained in the compressed air affects the efficiency of the filter. For example, when the temperature is 30°C, the oil content flowing through the filter is 5 times higher than when it is 20°C: when the temperature rises to 40°C, the oil content flowing through the filter is 10 times higher than when it is 20°C. So, the filter should normally be installed at the lowest temperature point of the compressed air system.