The selection of metering pumps should pay attention to the following points: To determine the pressure: The selected pressure pump rated pressure slightly higher than the actual maximum pressure required, generally higher than 10 to 20%. Do not choose too high, the pressure is too high will waste energy, increase equipment investment and operating costs; determine the flow: the selected metering pump flow should be equal to or slightly greater than the flow of technology required. Dosing pump flow range of use in the metering pump rated flow range of 30 to 100% better, then the metering pump repeated reproduction of high precision. Taking into account the economical and practical, it is recommended that the actual need for metering pump flow metering pump rated flow of 70 to 90%; determine the pump head (hydraulic end) Material: metering pump specific model specifications are determined, and then according to the properties of the over-flow medium Select the flow of the material part, this step is very important, if not properly selected, will cause corrosion of the medium overcurrent parts or media leak contaminated systems. Serious accidents may also result. Other aspects: In the choice of metering pumps, but also need to consider the required level of precision metering pump, the higher the level of precision into more. Metering pump general operating temperature -30 ~ 100 ℃, special metering pump its working temperature range is wider (such as high temperature liquid metering pump with insulation jacket, the delivery temperature up to 500 ℃). For the media size, the requirement should be less than 0.1mm, for media greater than 0.1mm, can be targeted to the pump overcurrent structure to be changed to meet the needs. The viscosity of the medium should be generally 0 ~ 1000mm / s, special metering pump up to 6000 mm2 / s, the flow of mechanical diaphragm metering pump is the maximum flow measured under the rated pressure (water transport at room temperature ), If the pressure drops, the output of the flow rate will be higher than the calibration. Metering pump features Measuring range: 0-400 liters / ha Pressure range: 0-1.0 MPa Driving mode: Motor drive Control mode: Manual, automatic control (can receive 4-20mA signal to regulate the flow) 1, , High heat dissipation, overall light weight, suitable for all kinds of acid-base liquid, non-toxic and tasteless. 2, the cam mechanism. Completely leak-free, can be placed in medicine troughs or pipes. 3, the contact medium pump head for PVC, optional PTFE, and stainless steel. 4, cost-effective, generally applicable to, pressure less demanding water treatment industry. 5, the pump operation or stop can also be adjusted when the flow rate can also be quantitative output. 6, the diaphragm is made of multi-layer composite structure suppression, the first layer of ultra-tough Teflon acid-resistant film, the second layer of EPDM elastic rubber, the third layer thickness support iron core, the fourth layer reinforced nylon fiber reinforcement, the fifth EPDM Fully elastic rubber package, which can effectively enhance the diaphragm life.