Dosage without the use of electricity. Doses only by means of water pressure and flow and 100% proportional to water pressure and flow. Constant and accurate dosage of all types of liquid additives. Many years of experience with dosage in many industries and applications. Water flow: 10 to 2,500 liters per. hour. Dosage between 0.2 - 2%. Pressure: 0.3 - 6 bar. External dosage (chemistry dosed outside pump housing).