(1) metering pump selection points:
According to requirements of different occasions, how in a variety of different types of metering pump properly selected, have the following information is very important.
1) traffic is metered liquid on the measurement accuracy requirements.
2) The main characteristics of metering liquids, such as chemical resistance, viscosity, concentration and density.
3) backpressure system.
4) suitable suction lift.
5) other options needed, such as analog control, pulse volume control, flow monitoring and timer.
6) Environmental requirements for the equipment.
(2) the types and characteristics of metering pumps:
Metering pump fluid end structure in the form can be divided into piston metering pumps and diaphragm metering pumps, which are divided into ordinary piston metering pumps have valveless piston pump and two pump; diaphragm metering pump into mechanical diaphragm metering pumps, hydraulic diaphragm metering pumps and bellows metering pumps. Metering pump according to the driving form points, can be divided into electromagnetic drive metering pumps and motor-driven metering pumps, in addition, there are hydraulic drive, pneumatic drive in the form of a metering pump.
1) piston metering pumps: piston metering pumps are divided into a valve pumps and valveless pump while both (Figure 8-23). Piston metering pumps because of its simple structure and high temperature and high pressure, etc. are widely used in the petrochemical industry. For high viscosity media in high pressure conditions less than ordinary piston pump A valveless rotary piston metering pumps by more and more attention, it is widely used in syrups, chocolate and oil additives, high viscosity media Metering add. Having been unable to achieve complete isolation between the measurement medium and pump lubricant this structural disadvantage, piston metering pumps in high-pollution requirements for fluid delivery measurement applications subject to many restrictions.