Micro vacuum pump, micro air pump selection instructions

With the vigorous development of the instrumentation industry, miniature vacuum pumps and miniature air pumps that are compact, oil-free and environmentally friendly have become more and more widely used. How can we choose the most appropriate product among a wide range of micropumps?

First, we must clarify the purpose of the micro pump. We will discuss them one by one in three categories.

1. If you only use a micro air pump to output compressed air. Simply put, it is only used for pumping and inflating, and the suction port of the pump is basically not used. This situation is relatively simple. You can choose from highest to lowest output pressure: PCF5015N, FAA8006, FAA6003, FAA4002, FM2002, FM1001. Of course, also refer to the relevant technical parameters such as flow indicators.

2. In the following situations, WKA series products should be used. 1. Use a micro pump to pump air or vacuum, but sometimes liquid water enters the pump cavity. 2. The micro pump is required to pump both air and water. 3. Mainly use micro pumps to pump water, but do not want to manually add water before pumping. (Some water pumps need to manually add some "diversion" before working, so that the pump can pump up the low water, otherwise the pump will not be able to pump water or even be damaged.) The advantage of WKA series products is that they will pump when they are not in contact with water. Vacuum, after forming a vacuum, press the water up by air pressure, and then start pumping. 4. Use a micro-pump to pump water, but sometimes the pump may have no water to pump and it is in a "dry running" state. Some traditional water pumps are afraid of "dry running", even fatal. The WKA series product is essentially a compound function pump, which integrates the functions of a vacuum pump and a water pump. Some people call it a "vacuum water pump". Therefore, in the absence of water, it will vacuum, and when there is water, it will pump water. Whether it is pumped or pumped, it belongs to the scope of normal work, and there is no such thing as "dry running" damage.

3. The situation is slightly more complicated if the air is pumped by a micro pump.

(1) Judging the working conditions of the suction side of the micro pump. The micro pumps used for pumping are divided into two categories: gas sampling pumps and micro vacuum pumps. Although they are usually simply referred to as miniature vacuum pumps without distinction, they are different from a technical point of view, and special attention should be paid to the selection. In short, the gas sampling pump can only carry a small load (that is, the resistance of the pump suction side cannot be too large), but the price is cheap; in a strict sense, the miniature vacuum pump can carry a large load (the suction side allows large resistance, even complete Blocked), but slightly more expensive. The specific differences between the two can be found in the article "On the difference between micro vacuum pumps and gas sampling pumps", which will not be repeated. Gas sampling pumps are: PM series, SA series, SB series; miniature vacuum pumps: VM series, VAA series, PK series, PC series, VCA series, VCC series, VCH series, VBH series, FM series, FAA series, PCF series , All specifications under these series are real miniature vacuum pumps, such as VM7002, VAA6005, PC3025N, etc. The resistance of the suction end of the micropump can be measured with an instrument. Compare it with the Por value of the pump's technical parameter "Maximum Allowable Resistance at the Air Inlet" to know whether the selection is appropriate. It is usually determined by a simple method based on experience. For example, the following situations are due to the large load (that is, the resistance of the pumping end of the pump is large), and the selection can only be made within the range of the micro vacuum pump: ① Connect a very long pipeline, or the pipeline has many bending points, severe bends, or even blocked or closed, or the inner hole of the pipeline is small (for example, less than φ2 mm); ②There are throttle valves, solenoid valves, gas switches, and filters in the pipeline And other components; ③The pump suction port is connected with a closed container, or the container is not sealed but the air intake is small; ④The pump suction port is connected with a suction cup to absorb objects (such as integrated blocks, precision workpieces, etc.); The suction end is connected to the filter container, and a filter screen is placed at the mouth of the container to accelerate liquid filtration.

(2) Judging the working conditions of the exhaust end of the micropump The above are all discussing the resistance of the exhaust end of the micropump. According to these judgment conditions, the selection range has been narrowed, but the exhaust end resistance must also be considered. Finally determine the optional range. In practical applications, the exhaust conditions faced by miniature vacuum pumps are different: one is that the exhaust is very smooth and direct to the atmosphere; the other is that the exhaust resistance is large, such as valves and small elbows in the exhaust pipe , Large damping sensor, non-dedicated muffler, exhaust below the liquid level, gas exhaust to a closed or semi-closed container, etc. In modern design and manufacturing, miniature vacuum pumps facing different exhaust conditions are treated differently. The parameter "Por value of the maximum allowable resistance of the 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. Simply put, for systems with large exhaust resistance, our selection range is: FM series, FAA series, PCF series; for systems with low exhaust resistance, the selection range is: VM series, VAA series, PK series, PC series, VCA series, VCC series, VCH series, VBH series. According to the above steps, we can already determine the selection range of the micro pump. Among the selected series, the specific model can be determined according to our requirements for flow and vacuum. For products of poor quality that are not included in this article, try not to use them. Note that there should be margin for parameter selection, especially flow parameters. After the pump is connected to the gas circuit system, due to the pressure loss caused by the gas circuit components such as pipes and valves, the flow will be attenuated. Therefore, the flow rate obtained is less than the nominal flow rate of the pump. There are also some selection-related problems listed below, according to the usage consider.

1. Start with load. If the micro air pump has vacuum at its suction port or pressure at its exhaust port before it is started, another technical parameter of the pump must be considered: the maximum starting load at the intake port Pis and the maximum starting load at the exhaust port Pos. 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 powered on and stopped when it is higher than the set value. Products that can be started under the ultimate vacuum that they can reach are: VM series, VAA series, PK series, PC series, VCA series, VCC series, VCH series, VBH series; they can be started under the maximum output pressure that they can reach The products are: FM series, FAA series, PCF series. This performance has higher requirements on the manufacturer's technical level.

2. The medium temperature of the micro pump. According to the temperature of the medium gas passing through the pump, it is possible to choose the normal type or the high temperature type.

3. The reliability of the micro pump. According to the seriousness of the consequences after the failure of the micro pump, it is completely according to your 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. Note that this parameter is measured under full load and uninterrupted operation, which 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 condition of the pump. set. This performance is entirely a test of the manufacturer's technical strength. Some can be seen from the appearance of the product, such as the use of special motors instead of ordinary low-cost motors, and the weight is heavier in the case of equivalent volume. According to the product price, you can also know a little bit.

4. The electromagnetic interference problem of the micro pump. If there is a precision circuit to control the micro pump, depending on the circuit's anti-interference ability, it may be necessary to order a micro pump with low electromagnetic interference.