1.Definition of dosing pump

    dosing pump is a kind of special volumetric pump that can meet the needs of various strict processes, the flow rate can be steplessly adjusted in the range of 0-100%, used to transport liquids (especially corrosive liquids). dosing pump is also called quantitative pump or proportional pump. dosing pump belongs to reciprocating volumetric pump, used for precise measurement, usually requires dosing The stability accuracy of the dosing pump does not exceed ±1%. With the continuous development of modern industry towards automatic operation and remote automatic control of this situation, dosing pump's supporting strong, adaptable medium (liquid) wide range of advantages is particularly outstanding.

Dosing pump also known as quantitative pump or proportional pump . dosing pump is a variety of strict process needs, the flow rate can be steplessly adjusted in the range of 0-100%, used to transport liquids (especially corrosive liquids) a special volume pump.

A dosing pump is a type of fluid transfer machine that is distinguished by its ability to maintain a constant flow rate independent of discharge pressure. The use of dosing pumps simplifies the production process by simultaneously performing the functions of conveying, metering and regulating. By using multiple dosing pumps, several media can be mixed in the process in exact proportion. Because of its own outstanding, metering pump has been widely used in petrochemical, pharmaceutical, food and other industrial fields.

2.dosing pump classification

    ⒈ According to the overflow part

    (1) plunger, piston type (2) mechanical diaphragm type (3) hydraulic diaphragm type

    ⒉ According to the drive mode

    (1) motor drive (2) electromagnetic drive

    ⑶ According to the working mode

    (1) reciprocating type (2) rotary type (3) gear type

    4、According to the pump characteristics

    (1) Extra large machine base (2) Large machine base (3) Medium machine base (4) Small machine base (5) Micro machine base

    Other classification methods: electric control type, gas control type, heat preservation type, heating type, high viscosity type, etc.

    Principle characteristics

3. Structure of dosing pump

    The pump is composed of three parts: motor, transmission box, and cylinder.

    The transmission box is composed of a worm gear mechanism, a stroke adjusting mechanism and a crank linkage mechanism; the stroke is highly adjustable by rotating the adjusting handwheel, thus changing the eccentric distance of the moving shaft to change the plunger (piston) stroke.

    The cylinder parts are composed of pump head, suction valve group, discharge valve group, plunger and packing seal.

4. Working principle of dosing pump

    The motor drives the worm through the coupling and decelerates the main shaft and eccentric wheel through the worm gear for rotary motion, and the eccentric wheel drives the sliding adjustment seat of the bow-type connecting rod for reciprocating motion. When the plunger moves to the back dead point, the pump cavity gradually forms a vacuum, the suction valve opens, and the liquid is sucked in; when the plunger moves to the front dead point, the suction valve closes and the discharge valve opens, and the liquid is discharged when the plunger moves further. In the pump reciprocating also work to form a continuous pressure, quantitative discharge of liquid.

    Flow rate adjustment

    The flow rate of the pump is adjusted by rotating the adjusting handwheel, driving the adjusting screw to rotate, thus changing the distance between the bow-type connecting rod and changing the plunger (piston) in the pump cavity to move the stroke to determine the size of the flow rate. The scale of the adjusting handwheel determines the plunger stroke, and the accuracy rate is 95%.

5.dosing pump features

    ⒈ the pump performance, including diaphragm metering pump absolutely no leakage, high safety performance, accurate measurement and delivery, the flow can be adjusted from zero to the maximum range of fixed values can be arbitrary, the pressure can be selected from atmospheric pressure to the maximum allowable range.

    ⒉Adjustment intuitive and clear, smooth work, no noise, small volume, light weight, easy maintenance, can be used in parallel.

    The pump is available in a wide range of products with full performance, suitable for conveying from -30 to 450 degrees Celsius, viscosity from 0 to 800 mm/s, maximum discharge pressure up to 64 MPa, flow rate from 0.1 to 20,000 L/h, and metering accuracy within ±1%.

    The pump can be manually adjusted or frequency-controlled according to process requirements, and can also be controlled remotely or automatically by computer.

6. Model introduction of the dosing pump

    Hydraulic diaphragm

    Drive mechanism

    (1) The motor power is transmitted to the worm gear and worm wheel for deceleration and rotation, which drives the reciprocating motion of the crankshaft and connecting rod mechanism to produce hydraulic force from the plunger.

    (2) The stroke adjustment mechanism consists of crankshaft, eccentric wheel, adjusting nut, adjusting screw, adjusting handwheel (handle), dial (pointer) and scale, which changes the eccentric distance to achieve the relative stroke of the plunger.

    Hydraulic system

    (1) hydraulic hydraulic diaphragm type metering pump hydraulic system, its structure consists of plunger, cylinder, cylinder cover, import and export valves, hydraulic diaphragm type and three valves (namely: bleed overload valve, limit valve, compensation valve). In the work of the diaphragm separates the hydraulic oil and media, so the hydraulic diaphragm type metering pump has the advantage of no leakage.

    (2) hydraulic diaphragm type metering pump hydraulic end of the plunger is driven by the reciprocating motion of the crank linkage mechanism at the drive end to work. Plunger in the hydraulic cavity for reciprocating motion, prompting the hydraulic oil pressure changes, so that the hydraulic diaphragm type flexural displacement to transport the medium, the relative stability of the hydraulic oil volume in the hydraulic cavity, the function of the three valves to maintain.

    (3) Overload valve automatically discharges the gas in the hydraulic oil into the hydraulic cavity to ensure smooth work and avoid excessive hydraulic oil or discharge pipeline obstruction to produce overpressure automatically open the load valve to achieve the purpose of protection.

    (4) The limit compensation device is to push the opening of the limit valve with the help of hydraulic diaphragm type, replenish the oil volume at any time according to the vacuum in the hydraulic cavity to ensure the hydraulic oil in the hydraulic cavity is full.

    dosing pump is widely used in petrochemical, chemical, power, water treatment, pharmaceutical and other types of industrial processes for quantitative delivery of various chemical additives.

    Electromagnetic diaphragm

    Overview

    Electromagnetic metering pump is the use of electromagnetic actuator driven diaphragm in the pump head reciprocating movement, causing the pump head chamber volume and pressure changes, pressure changes caused by the opening and closing of the suction valve and discharge valve, to achieve the quantitative liquid intake and discharge.　Electromagnetic metering pump is driven by an electromagnet, designed to convey a small flow of low pressure pipeline liquid and a metering pump, it is simple in structure, low energy consumption, accurate measurement and easy to adjust and welcomed in the industry, the design principle of "simple and practical", but its disadvantage is that the metering flow is small (commonly <90 liters per hour), the pipeline pressure requirements are relatively low. Requirements for pipeline pressure is relatively low, from some aspects to limit its application in industry.
                                                     

    Application: electromagnetic metering pump is widely used in petroleum, chemical industry, electric power metallurgy, mining, shipbuilding, light industry, agriculture, civil and national defense and other sectors. idose electromagnetic metering pump introduces and absorbs foreign production technology, the maximum flow rate can reach 100L/H; foreign monopoly of large flow electromagnetic metering pump.

    Mechanical plunger

    Overview

    There are mainly two kinds of ordinary valved pumps and non-valved pumps. The plunger metering pump is widely used in petrochemical industry because of its simple structure and high temperature and pressure resistance.

    in the petrochemical field. For high viscosity media in the high pressure working conditions of the ordinary plunger pump, a non-valved rotary plunger metering pump has received more and more attention, is widely used in sugar syrup, chocolate, cement grinding aid and petroleum additives and other high viscosity media metering adding. Because of the structural shortcomings of complete isolation between the measured medium and the lubricant inside the pump, the plunger type metering pump is limited in many applications with high anti-pollution requirements for fluid metering.

7.dosing pump installation matters

    1. the outlet is higher than the inlet, to avoid siphoning phenomenon

    2. The pump head and injection valve should be installed vertically

    3. The attached fittings can be screwed by hand, do not use tools; do not use raw material tape at the threads

    4. Stable power supply voltage and grounding

    5. Clean and spacious installation environment with good ventilation