Types and characteristics of dosing pump china and the way of flow regulation-JONSN

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Types and characteristics of dosing pump china and the way of flow regulation

2021-11-22

Types of dosing pump characteristics and flow rate adjustment.

dosing pump is also called quantitative pump or proportional pump. dosing pump belongs to reciprocating volumetric pump, used for precise metering, usually requires the stability accuracy of metering pump not more than ±1%.


dosing pump china


Types and characteristics of dosing pumps.

According to the type of structure of the hydraulic end of the dosing pump, the metering pump is often divided into plunger type, hydraulic diaphragm type, mechanical diaphragm type and bellows type four kinds.

① Plunger type metering pump. The structure of the pump is basically the same as the ordinary reciprocating pump, the hydraulic end of the cylinder, plunger, suction and discharge valves, seal packing and other components, in addition to meeting the design requirements of the hydraulic end of the ordinary reciprocating pump, the pump should also have an impact on the metering accuracy of the suction valve, discharge valve, seal and other components to carefully design and select.

② Hydraulic diaphragm type metering pump. Usually called diaphragm metering pump. Single diaphragm metering pump in the front of the plunger is equipped with a layer of diaphragm (plunger and diaphragm do not contact), the hydraulic end of the separation into the infusion chamber and hydraulic chamber. The infusion chamber is connected to the pump suction and discharge valve, and the hydraulic chamber is filled with hydraulic oil (light oil) and connected to the hydraulic oil tank (refill tank) at the upper end of the pump body. When the plunger moves back and forth, the pressure is transmitted to the diaphragm through the hydraulic oil and deformation caused by the volume change after the previous flexure, to play a role in conveying liquid and meet the requirements of accurate metering.

③ mechanical diaphragm type metering pump. The diaphragm is connected to the plunger mechanism, no hydraulic oil system, the back and forth movement of the plunger directly drive the diaphragm back and forth deformation.

④Bellows type metering pump. Structure and mechanical diaphragm metering pump is similar, but the bellows instead of diaphragm, the end of the plunger and bellows fixed together. When the plunger reciprocates, the bellows is stretched and compressed, thus changing the volume of the liquid cylinder to achieve the purpose of liquid delivery and metering.


dosing pump manufacturer


Flow rate adjustment of dosing pump.

The common way to adjust the flow of dosing pump is to adjust the plunger (or piston) stroke, adjust the number of plunger reciprocation or both of these three methods, among which the way to adjust the stroke is most widely used. This method is simple, reliable and can maintain high metering accuracy at low flow rates. There are three ways of stroke adjustment as follows.

① Parking manual adjustment. The stroke of the metering pump is adjusted manually when it is stopped.

②Manual adjustment during operation. In the pump operation to change the axial displacement, in order to indirectly change the crank radius, to achieve the purpose of adjusting the stroke length. Commonly used methods include N-shaped crankshaft adjustment, L-shaped crankshaft adjustment and eccentric cam adjustment, etc.

③ Automatic adjustment in operation. There are two common types of pneumatic control and electric control. Pneumatic control is to change the air source pressure signal to achieve the purpose of automatic adjustment of stroke. Electric control is to change the electric signal to achieve the purpose of automatic adjustment of stroke.

Three valves of dosing pump.

In the diaphragm metering pump, in order to make the diaphragm of the diaphragm metering pump can work properly, so the volume of the hydraulic oil in the closed space of the hydraulic chamber of the metering pump must be required to remain unchanged; this will ensure that the volume formed by the reciprocating movement of the diaphragm is always equal to the stroke volume of the plunger, thus maintaining the flow of the diaphragm metering pump remains unchanged. But in the actual use of the metering pump, due to the plunger sealing place will be difficult to produce leakage phenomenon, leakage at the same time there may be gas into the hydraulic chamber inside. If too much oil is replenished or the pressure of the discharge line is unexpectedly increased, there will be a change in the volume of the liquid in the hydraulic cavity phenomenon, which affects the amount of metering pump flow is unstable, thus reducing the metering accuracy of the metering pump. So in order to solve the above problems, each metering pump are used the so-called three-valve device, actually refers to the hydraulic cavity supporting the compensation valve, bleed valve, safety valve and other three functions of the device or device combination. According to the different principles of its role, also known as automatic compensation three-valve device.

Automatic compensation three-valve device in the diaphragm metering pump is very widely used, especially in the case of suction height requirements, can only use this compensation device.

1.dosing pump safety valve role

The role of dosing pump safety valve is to ensure that the pressure in the hydraulic chamber does not appear abnormal phenomenon to protect the role of the diaphragm. When the hydraulic oil inside the hydraulic cavity because of oil overrun, the diaphragm reaches the front limit plate and the laurel plug has not yet reached the end of the discharge stroke, the cylindrical plug will still move forward, the pressure inside the hydraulic cavity will rise sharply, then the safety valve of the metering pump should quickly open. At the same time, the safety valve in the discharge line pressure is not normal rise, metering pump safety valve can also play a role in protecting the metering pump is not damaged. The metering pump safety valve opening pressure should be easy enough to fine and accurate adjustment.

2.dosing pump bleed valve role

As the plunger seal can not completely avoid the entry of gas. Other situations such as refueling gas may also enter the hydraulic chamber, the formation of air pockets will greatly affect the accuracy of measurement. Therefore, it is necessary to set a bleeder valve. The bleeder valve should be set at the highest point of the hydraulic chamber to facilitate the discharge of gas.

3.The role of dosing pump compensation valve

dosing pump in the long operation process. With the plunger seal at the work medium leakage amount increases. The amount of oil in the hydraulic chamber will gradually decrease. In the suction stroke, the diaphragm has reached the rear limit plate. And the plunger has not yet reached the post-dead point, in the hydraulic chamber will form a transient vacuum, so that the flow rate drops. Therefore, a compensation valve is needed to automatically compensate for the oil loss in the hydraulic chamber when a transient vacuum occurs.

dosing pump compensation valve

Forced compensation of the three-valve device regardless of the need for oil replenishment, whenever the plunger reaches the post-dead point, the device makes the oil replenishment motor and hydraulic chamber connected, at this time the oil replenishment or not is determined by the pressure foot of both. Forced compensation three valves are also set in the highest part of the hydraulic cavity, in the filling oil at the same time has the function of bleeding.

dosing pump is a special form of reciprocating displacement pump whose flow can be steplessly adjusted within the range of 0-100% and is used to convey liquid materials (especially corrosive and dangerous liquids), dosing pump china is also called quantitative pump or proportional pump, dosing pump china is also called barrel pump china.