Diaphragm micro liquid pump is a kind of pump that is widely used in the fields of chemical, medical, biopharmaceutical, and analytical equipment to transfer liquids. It is small in size, highly reliable, corrosion-resistant, will not pollute the medium, and has self-priming and high pressure.
Diaphragm liquid pump is a positive displacement pump. It drives the crankshaft through the rotation of the motor, pushes a diaphragm usually made of rubber to reciprocate, and continuously changes the volume of the pump chamber with the cooperation of the one-way valve to realize the suction and discharge of fluid. So what are the key characteristics of diaphragm pumps?
The principle of diaphragm liquid pump is not to transmit fluid through the common kinetic energy transmission method of impeller rotation to drive liquid movement, so that it can be used to transmit liquid, gas, or gas-liquid mixed medium, so it has some Special advantages, such as scenarios that may cause the pump to run dry, or scenarios where the liquid contains a lot of bubbles, it is not suitable to use an impeller pump. At this time, the gas-liquid dual-purpose characteristics of the diaphragm pump can be very good.
In different industries, it may be used to transport different chemical media. Common challenges encountered by liquid pumps include acidic media, alkaline media, and organic solvents. If these media react chemically with the pump head, pipelines, and seals, the system will fail. Therefore, when designing the fluid system, the media composition and corrosion resistance need to be considered.
Micro liquid pump head material
The material of the pump head is the core factor affecting the corrosion resistance. For manufacturers of high-end diaphragm pumps, they generally provide customers with a variety of pump head materials to choose from, such as polycarbonate (PC), nylon (PA), polyphenylene sulfide (PPS) and other common engineering plastics, as well as special applications. Pump heads made of PTFE, PVDF and other materials used in corrosion-resistant scenarios. These different materials can affect the mechanical properties of the pump head, can also affect the corrosion resistance, of course, also have an impact on the cost.
Elastomer material of micro liquid pump
Diaphragm pumps have elastic elements such as diaphragms and one-way valves. These elastic elements also have a key influence on fluid transmission and corrosion resistance. When considering the corrosion resistance of liquid pumps, it is necessary to simultaneously consider the material of the pump head and the material of the elastomer. Common diaphragm elastomers include ethylene propylene diene rubber (EPDM), fluorine rubber (FKM), silicone rubber, perfluoroether rubber (FFKM) and so on. For special corrosion-resistant scenes, in addition to using special rubber materials, you can also increase the corrosion resistance of the elastomer by adding a PTFE coating to the rubber standard layer.
When transferring liquid, different applications have different requirements on the fluid characteristics of the pump, such as whether the flow output is smooth, whether it will produce a shear effect on the fluid, and the self-priming height, flow rate, outlet pressure and other fluid properties of the pump itself. Both are issues that need to be considered when using diaphragm pumps.
Pulsation of liquid pumps
Diaphragm micro liquid pumps are reciprocating positive displacement pumps. When it outputs fluid, it is not a smooth output. Second, it has a certain pulsation along with the reciprocating movement of the diaphragm. From a micro point of view, the flow is output intermittently. This kind of pulsation will vibrate the external pipeline, and will also affect some specific applications and analysis. The current methods to solve the pulsation include the installation of pulse dampers in the pipeline, the use of pump heads with multiple pump chambers, and the use of specially designed pump heads with pulse damping, all of which can effectively reduce the pulsation.
Shearing of the fluid
When the pump is transporting fluid, it will generate shear force on the medium. This shear force has a huge impact on some applications such as inkjet printing and the transport of active biological media. Therefore, in some applications, it is necessary to produce as low a shear force as possible on the fluid. A specially designed pump head can solve this problem.
Also called the self-priming height, the diaphragm micro liquid liquid pump can create a vacuum to suck the liquid into the pump cavity from a low place, without the need to fill the pump cavity with liquid in advance to work. Therefore, the diaphragm pump is also a self-priming pump. The self-priming performance is determined by the vacuum performance of the pump. When the diaphragm liquid pump can create a higher vacuum, the negative pressure can be used to suck the liquid into the pump cavity from a lower place.
Modern diaphragm micro liquid pumps, in addition to transporting liquids, can also adjust the flow of transporting gases and liquids. The flow can be adjusted by changing the volume of the pump chamber or the working speed of the pump. The liquid pump with adjustable flow can meet the needs of users more flexibly. Furthermore, it can be used as a metering pump to accurately measure the amount of liquid to be transferred.
Liquid viscosity is also a key indicator for micro liquid pumps, and low-viscosity liquids do not require special consideration. However, when transferring high-viscosity liquids, the viscosity of the liquid will pose a challenge to the pump. High-viscosity liquids will greatly affect the opening and closing performance of the one-way valve, thereby affecting the operation of the pump. Generally, when transferring high-viscosity liquids, special design of the pump structure is required, or other types of liquid pumps such as gear pumps are used.
What is the allowable fluid outlet pressure of the liquid pump. For high-pressure applications such as high-pressure cleaning, this is a key indicator. The higher the outlet pressure, also has a certain impact on the strength of the external pipeline. When the pipeline cannot withstand the corresponding pressure, leakage accidents are prone to occur. Generally, the outlet pressure that the diaphragm pump can reach is in the range of 1 bar to 6 bar. At higher pressures, other types of liquid pumps such as gear pumps and plunger pumps are generally required.
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