First, if only a micro air pump is used to output compressed air.
Simply put, it is only used for inflating and inflating, and the air inlet of the pump is basically not used. This situation is relatively simple, and the output pressure can be selected in descending order: PCF50 15N, FAA8006, FAA6003, FAA4002, FM2002, FM 100 1+0. Of course, we should also refer to relevant technical parameters such as flow indicators.
Secondly, PHW600B or WAA series products should be selected if.
1. Use a micro pump to pump air or vacuum, but sometimes liquid water will enter the pump cavity.
2. Micropumps need to pump air and water.
We mainly use micropumps to pump water, but we don't want to rely on manual "water diversion" before pumping water. (Some pumps need to manually add some "water diversion" before working, so that the pump can pump up the water at the lower part, otherwise the pump will not pump water or even be damaged. ) The advantages of PHW600B or WAA series products are: when it is not in contact with water, vacuum is pumped, after vacuum is formed, the water pressure is increased by air pressure, and then water is pumped.
4. Pump water with a micro-pump, but sometimes the pump may have no water to pump and be in a "dry operation" state. Some traditional water pumps are afraid of "dry running" and even fatal. PHW600B or WAA series products are essentially a kind of compound function pump, which integrates the functions of vacuum pump and water pump. Some people call it "vacuum pump". Therefore, in the absence of water, when there is water, vacuum will be pumped. Both the pumping state and the pumping state belong to the normal working category, and there is no "dry rotation" damage.
Third, if the pump is used, the situation is a little more complicated.
(1) Judge the working state of the suction end of the micropump.
Micro-pumps used to pump air can be divided into two categories: gas sampling pumps and micro-vacuum pumps. Although they are always simply called micro vacuum pumps indiscriminately, they are different from each other from a technical point of view, so special attention should be paid when choosing them.
In short, the gas sampling pump can only carry a small load (that is, the resistance at the suction end of the pump cannot be too large), but it is cheap; Strictly speaking, the micro vacuum pump can carry a large load (the suction end allows a large resistance, or even a complete blockage), but the price is slightly expensive. The specific difference between the two can be found in the article "Difference between Micro Vacuum Pump and Gas Sampling Pump", which is not repeated here.
Gas sampling pumps include: PM series (specific models: PM950.2, PM850.5, PM800 1, PM7002, PM 6503); Micro vacuum pumps include: VM series, VAA series, PK series, PC series, VCA series, VCC series, VCH series, PH series, FM series, FAA series and PCF series. All specifications under these series are real micro vacuum pumps, such as VM7002, VAA6005 and PC3025.
The resistance at the suction end of the micropump can be measured by instruments. By comparing with the technical parameter Por value of the pump, we can know whether the selection is appropriate. It is usually determined by a simple method based on experience. For example, the following situations are all heavy loads (that is, the resistance at the suction end of the pump is large) and can only be selected within the scope of the micro vacuum pump: ① The suction end of the pump is connected with a long pipeline, or the pipeline has many bending points, which may even be blocked and closed, or the inner hole of the pipeline is very small (for example, less than φ 2mm); ② Throttle valve, solenoid valve, gas path switch, filter and other components are arranged on the pipeline; ③ The suction port of the pump is connected with a closed container, or the container is not closed but the air intake is small; (4) The suction port of the pump is connected with the sucker for adsorbing objects (such as integrated blocks and precision workpieces); ⑤ The suction end of the pump is connected with the filter container, and a filter screen is placed at the container mouth to accelerate the liquid filtration.
(2) jud that working state of the exhaust end of the micropump
All of the above are discussing the resistance at the suction end of the micropump. According to these judgment conditions, the range of type selection is narrowed, but the resistance of exhaust end must be considered before the optional range can be finally determined.
In practical application, the exhaust situation of micro vacuum pump is different: one is that the exhaust is smooth and straight to the atmosphere; The other is high exhaust resistance, such as valves, small elbows, large damping sensors, non-dedicated silencers, exhaust below the liquid surface, and gas discharged into closed or semi-closed containers. In modern design and manufacture, micro vacuum pumps facing different exhaust conditions are treated differently. The parameter "Por value of allowable maximum resistance of exhaust port" is to calibrate the exhaust capacity of the pump, so that we can use strict technical means to determine whether the selection is appropriate.
To put it simply, for systems with high exhaust resistance, our selection ranges are: FM series, FAA series and PCF series; For the system with low exhaust resistance, the selection range is: VM series, VAA series, PK series, PC series, VCA series, VCC series, VCH series and PH series. According to the above steps, we can already determine the selection range of micro-pump. In several optional series, the specific model can be determined according to our requirements for flow and vacuum. Products with poor quality are not included in this article, so try not to choose them. Pay attention to the parameter selection to leave margin, especially the flow parameter. After the pump is connected to the gas path system, the flow rate will be attenuated due to the pressure loss caused by gas path components such as pipelines and valves, so the obtained flow rate is less than the nominal flow rate of the pump.
There are also some problems related to the selection listed below, which should be considered according to the use situation.
1. Start with the load.
If there is vacuum in the suction port or pressure in the exhaust port before the micro air pump is started, we should consider another technical parameter of the pump: the maximum starting load Pis at the inlet and the maximum starting load Pos at the exhaust port. A typical application example is to use a micro air pump to maintain the vacuum or positive pressure in the container. When the vacuum or positive pressure in the container is lower than the set value, the pump needs to be energized, and when it is higher than the set value, it stops. Products that can be started under their own extreme vacuum are: VM series, VAA series, PK series, PH series, VCA series, PC series, VCC series and VCH series; Products that can be started under the maximum output pressure are: FM series, FAA series and PCF series. This performance requires a higher technical level of the manufacturer.
2. Medium temperature of the micropump.
According to the temperature of the medium gas flowing through the pump, choose ordinary type or high temperature type.
3. Reliability of micropump.
According to the seriousness of the consequences of micro-pump failure, completely according to their own requirements. The average trouble-free continuous running time of high-quality products is more than 1000 hours, and some are as high as thousands of hours. Pay special attention to this parameter, which is measured under full load and uninterrupted operation, and is the worst working condition. If the actual use is not full load or continuous operation, the value will be higher, depending on the working conditions of the pump. This kind of performance is a test of the technical strength of the manufacturer, which can be seen from the appearance of the product. For example, replacing ordinary low-priced motors with special motors is heavier under the same volume. You can also know a thing or two according to the product price.
4. Electromagnetic interference of micropump.
If there is an accurate circuit to control the micropump, according to the anti-interference ability of the circuit, it may be necessary to order a micropump with low electromagnetic interference.