Detailed model selection instructions for the hott

With the vigorous development of China's instrument industry, miniature vacuum pumps and miniature air pumps with small volume, oil-free and environmental protection are more and more widely used. How can you choose the most suitable product among the various micro pumps

according to the purpose of the micro pump, it can be divided into three categories for discussion:

first, if you only use the micro air pump to output compressed air

simply put, it is only used to pump and inflate air, and the air extraction port of the pump is basically not used. This situation is relatively simple. It can be selected according to the output pressure from large to small: pcf5015n, faa8006, faa6003, faa4002, fm2002, fm1001, HRB400 6 ⑵ 5. Of course, refer to flow indicators and other relevant technical parameters

II. In the following cases, phw600b or WAA series products should be selected

1. Use a micro pump to pump air or vacuum, but sometimes liquid water will enter the pump chamber

2. The micro pump is required to be able to pump both air and water

3. Mainly use micro pumps to pump water, but don't want to manually add "water diversion" before pumping (some pumps need to manually add some "water diversion" before working, so that the pump can pump up the water at the low place, otherwise the pump can't pump water or even damage.), That is, the pump is expected to have a "self-priming" function. The advantage of phw600b or WAA series products is that when it does not touch water, it vacuumizes, forms a vacuum, and then uses air pressure to raise the water pressure, and then starts pumping water

4. Use a micro pump to pump water, but sometimes the pump may not have water to pump, and it is in a "dry running" state. Some traditional pumps are afraid of "dry running", which may even damage the pump. Phw600b or WAA series products are essentially a composite function pump, which integrates the functions of vacuum pump and water pump. Some people call it "vacuum pump". Therefore, when there is no water, it will vacuumize, and when there is water, it will pump water. Both the pumping state and the pumping state belong to the normal working scope, so there is no so-called "dry rotation" damage

third, if you use a micro pump for air extraction, the situation is slightly more complex, and you can roughly decide the type selection from the following two aspects:

(I) judge the working condition of the pumping end of the micro pump

micro pumps used for air extraction are divided into two categories: gas sampling pumps and micro vacuum pumps. Although they are usually simply referred to as micro vacuum pumps without distinction, they are different from each other 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 at the pumping end cannot be too large), but the price is cheap; Strictly speaking, the micro vacuum pump can carry a large load (the exhaust end allows large resistance, or even completely blocked), but the price is slightly expensive. The specific differences between the two can be seen in the article "about the difference between micro vacuum pump and gas sampling pump" in the "test data" of our company, which will not be repeated

gas sampling pumps include: PM series (specific models such as pm950.2, pm850.5, pm8001, pm7002, pm6503); Micro vacuum pumps include VM series, VAA series, PK series, PC series, VCA series, VCC series, VCH series, pH series, FM series, FAA series, PCF series. All specifications under these series are real micro vacuum pumps, such as vm7002, vaa6005, pc3025, etc

the resistance at the suction end of the micropump can be measured with an instrument. By comparing it with the por value of the pump's technical parameter "maximum allowable resistance at the inlet" (see the detailed parameters of VM series for the definition of "por at the inlet"), we can know whether the model selection is appropriate. It is usually determined by simple methods based on experience. For example, the following cases are all of large load (i.e. the resistance at the suction end of the pump is large), and can only be selected within the scope of micro vacuum pump:

a long pipe should be connected at the suction end of the pump, or the pipe has many bending points, severe bending, or even blocking and sealing, or the inner hole of the pipe is very small (such as less than ∮ 2mm through transformation)

there are throttle valve, solenoid valve, air circuit switch, filter and other components on the pipeline

the pump outlet is connected with the closed container, or the container is not closed but the air intake is small

the pump suction port is connected with the suction cup for adsorbing objects (such as manifold blocks, precision workpieces, etc.)

the air extraction end of the pump is connected with the filter container, and a filter is placed at the mouth of the container to accelerate liquid filtration

(II). Judging the working condition of the exhaust end of the micropump

the above are all about the resistance at the exhaust end of the micropump. According to these judging conditions, the scope of model selection has been reduced, but the resistance at the exhaust end must also be considered, so that the optional range can be finally determined

in practical applications, the exhaust conditions faced by micro vacuum pumps are different:

one kind is that the exhaust is very smooth and directly connected to the atmosphere

the other is that the exhaust resistance is large, such as valves, small elbows, large damping sensors, non dedicated silencers on the exhaust pipeline, exhaust below the liquid level, and the gas is discharged to 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 the maximum allowable resistance at the exhaust port" (see the detailed parameters of VM series for the definition of "por at the exhaust port") is to calibrate the exhaust capacity of the pump, so that we can use strict technical means to determine whether the model selection is appropriate

in short, 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, pH series

according to the above steps, we can determine the selection range of micropump. Among the several optional series, the specific model can be determined according to our requirements for flow and vacuum

note that there should be allowance for parameter selection, especially flow parameters. After the pump is connected to the gas circuit system, the flow will be attenuated due to pressure loss caused by gas circuit components such as pipes and valves, so the flow obtained is less than the nominal flow of the pump

the following are other problems related to model selection, please consider according to the use situation:

1. Starting with load

if there is vacuum at the suction port or pressure at the exhaust port of the micro air pump before starting, 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 port (see the detailed parameters of VM series for the definitions of these two values). A typical application example is to use a micro air pump to maintain the vacuum or positive pressure state in the container. When the vacuum or positive pressure in the container is lower than the set value, the hardness values of Hb, HRB (or HRC) and HV are measured. The pump needs to be powered on and started, and shut down when it is higher than the set value

products that can be started under the extreme vacuum they can reach are: VM series, VAA series, PK series, PC series, VCA series, VCC series, VCH series, pH series

products that can be started under the maximum output pressure they can reach are FM series, FAA series and PCF series

this performance requires a higher technical level of the manufacturer

2. Medium temperature of micropump

according to the temperature of the medium gas passing through the pump, choose the ordinary type or the high-temperature type

3. Reliability of micropump

it depends on the severity of the consequences after the micro pump breaks down, completely according to your own requirements. The average trouble free continuous operation time of high-quality products is more than 1000 hours, and some are as high as thousands of hours. Pay special attention to 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, and the higher value depends on the working condition of the pump. This performance is entirely a test of the manufacturer's technical strength. It can be seen from the appearance of the product, such as the use of special motors instead of ordinary low-cost motors, heavy weight in the case of equivalent volume, etc. We can also know a little according to the product price

4. Electromagnetic interference of micropump

if there is a micro pump controlled by a precision circuit, it may need to order a micro pump with low electromagnetic interference depending on the anti-interference ability of the circuit