How to select miniature vacuum pump/miniature air pump?
According to the purpose of the micro pump, it can be divided into several categories to discuss:
One, if only with the micro air pump output compressed air.
Simply put, it is only used for pumping, inflating, pump suction port is basically not used. This situation is relatively simple, according to the output pressure from large to small optional: of course, but also refer to the flow indicators and other related technical parameters.
Two, if it is pumped with a micro pump, the situation is slightly more complicated, roughly can be decided from the following two aspects:
1. Judge the working condition of the pumping end of the micro pump
There are two types of micro pumps for air extraction: gas sampling pumps and micro vacuum pumps. Although they are usually referred to as miniature vacuum pumps indiscriminately, they are different from the 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 pump pumping resistance should not be too large), but the price is cheap; Strictly miniature vacuum pumps can carry large loads (the suction end allows large resistance, or even complete blockage), but are slightly more expensive.
The size of the resistance of the suction end of the micro pump can be measured by the instrument, and the technical parameters of the pump "maximum allowable resistance of the air inlet" Por value can be compared to know whether the selection is appropriate. It is usually determined by a simple method according to experience. For example, the following situations are characterized by large load (that is, large resistance at the pumping end of the pump), and can only be selected in the range of miniature vacuum pumps:
2. Judge the working condition of micro pump exhaust terminal
The above are all in the discussion of the resistance of the suction end of the micro pump. According to these judgment conditions, the scope of selection has been reduced, but it is also necessary to consider the resistance of the exhaust end, so as to finally determine the optional range.
In practical applications, the exhaust conditions faced by miniature vacuum pumps are different: one is that the exhaust is smooth and straight through the atmosphere; The other is the exhaust resistance is larger, such as in the exhaust pipe on the valve, small bend pipe, large damping sensor, non-special silencer, exhaust below the liquid level, gas discharged to closed or semi-closed containers, etc. In modern design and manufacture, the micro vacuum pump facing different exhaust conditions is treated differently. The parameter "maximum allowable resistance value of the exhaust port" is the calibration of the exhaust capacity of the pump, so that we can use strict technical means to determine
According to the above steps, we can determine the selection range of micro pump. In the selected series, the specific model can be determined according to our requirements for flow and vacuum.
Note that the parameter selection should leave a 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 the gas path components such as pipes and valves, so the flow rate obtained is less than the nominal flow rate of the pump.
Three, there are some problems related to selection listed as follows, according to the use of consideration.
1. Startup problem with load.
If the micro-air pump has a vacuum at its air outlet or a pressure at its exhaust outlet before starting up, another technical parameter of the pump should be considered: the maximum starting load Pis value of the air inlet and the maximum starting load Pos value of the exhaust outlet. A typical application example is to use a miniature 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 start with power, and stops when it is higher than the set value.
The performance requires high technical level of the manufacturer.
2, the micro pump medium temperature problem.
According to the temperature of the medium gas through the pump, choose the ordinary type or the high temperature type.
3, the reliability of the miniature pump.
According to the severity of the consequences after the failure of the micro pump, completely according to their own requirements. The average trouble-free continuous operation time of superior products is more than hours, some as high as thousands of hours. In particular, this parameter is measured in the full load, uninterrupted operation state, is the worst working condition, if the actual use is not full load or continuous operation, the value will be higher, how much depends on the pump working condition. This performance is a complete test of the manufacturer's technical strength, from the appearance of the product can be seen some, such as the use of special motor rather than ordinary low-price motor, the volume of the case of heavy weight, etc. Depending on the price of the product, you can get an idea.
4, the electromagnetic interference of the miniature pump.
If there is a precision circuit control micro pump, depending on the circuit anti-interference ability, may need to order low electromagnetic interference micro pump.