(A) hydraulic diaphragm metering pump: 1. Transmission mechanism 1.1 by the motor power transmitted to the worm, worm gear to achieve deceleration rotation, prompting the crankshaft connecting rod mechanism for reciprocating motion, driven by the plunger to produce hydraulic. 1.2 stroke adjustment mechanism by the crankshaft, eccentric, adjusting nut, adjusting screw, adjusting the handwheel (handle), dial (pointer) and ruler composition, by changing the eccentricity to achieve the relative stroke of the plunger. 2. Hydraulic system 2.1 Hydraulic diaphragm type metering pump hydraulic system, the structure of the plunger, cylinder block, cylinder head, import and export valves, hydraulic diaphragm and the three valves (ie: deflated overload valve, limit valve, Compensation valve). Separated by the diaphragm in the work of hydraulic oil and media, so the hydraulic diaphragm metering pump without leakage advantages. 2.2 hydraulic diaphragm metering pump Hydraulic end of the plunger by the transmission side of the reciprocating motion of the crank drive. Plunger reciprocating motion in the hydraulic chamber, prompting the hydraulic oil pressure changes, the hydraulic diaphragm flexure displacement to transport medium, the amount of hydraulic oil in the hydraulic chamber is relatively stable, the function of the three valves to maintain. 2.3 overload valve automatically discharge hydraulic oil into the hydraulic chamber gas to ensure smooth work to avoid excessive hydraulic oil or exhaust pipe obstruction overloaded automatically open the load valve to achieve the purpose of protection. 2.4 limit compensation device is to promote the use of hydraulic diaphragm limit valve open, according to the vacuum within the hydraulic chamber at any time to replenish the oil to ensure that the hydraulic chamber filled with hydraulic oil. Metering pumps are widely used in petrochemical, chemical, power, water treatment, pharmaceutical and other industrial processes for the quantitative delivery of various types of chemical additives. In 1936, the world's first motor-driven metering pump was invented; in 1939, Larry Wilson invented the Wilson chemical feeding equipment-the world's first hydraulic-driven diaphragm metering pump; in 1963, invented the world's first electromagnet Driven metering pump-LMI; 1965, invented the world's first pneumatic metering pump-WILLIAMS (B) of the electromagnetic diaphragm metering pump: electromagnetic metering pump is driven by electromagnetic push rod diaphragm reciprocating motion within the pump head, causing the pump head Cavity volume and pressure changes, pressure changes caused by liquid suction valve and drain valve open and closed, to achieve quantitative liquid inhalation and discharge. Electromagnetic metering pump is a kind of metering pump which is driven by electromagnet and designed for conveying low pressure and low pressure pipeline liquid. It is popular in the industry due to its simple structure, low energy consumption, accurate measurement and convenient adjustment. The design principle is "simple and practical", but its disadvantage is that the measurement flow is small (common applications: electromagnetic metering pumps are widely used in petroleum, chemical, power metallurgy, mining, shipbuilding, light industry, agriculture, civil and defense and other departments (3) Mechanical plunger metering pump: There are two kinds of ordinary valve pump and valveless pump.Plug metering pump is widely used in the field of petrochemical because of its simple structure and high temperature and pressure. Viscosity medium under the conditions of high pressure ordinary piston pump deficiencies, a valveless rotary piston metering pump by more and more attention, is widely used in syrup, chocolate, cement grinding aids and oil additives contour Viscosity of the metering medium due to the metering medium and pump lubricant can not be completely isolated between the structural shortcomings of the plunger metering pump in high anti-pollution Subject to many limitations in fluid metering applications.